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What are cyclones, hurricanes and typhoons?

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What are cyclones, hurricanes and typhoons?

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A typhoon expected to cause chaos in Japan this weekend has led to England's tie with France in the Rugby World Cup being cancelled.

Typhoon Hagibis is expected to make landfall in the capital, Tokyo, and other surrounding areas on Saturday, although other matches in the tournament may go ahead.

But what causes a typhoon and how are they different to cyclones and hurricanes?

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What are cyclones, hurricanes and typhoons?

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A typhoon expected to cause chaos in Japan this weekend has led to England's tie with France in the Rugby World Cup being cancelled. Typhoon Hagibis is expected to make landfall in the capital, Tokyo, and other surrounding areas on Saturday, although other matches in the tournament may go ahead.

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Hurricanes, Cyclones, and Typhoons Explained

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Hurricanes, Cyclones, and Typhoons Explained

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These giant, dangerous storms often cause substantial destruction.

Subjects

Earth Science, Meteorology

Image

Tropical Cyclone Amanda

The names of the powerful storms that form in the waters of the Atlantic and Pacific-whether hurricane, cyclone, or typhoon-depends on where they form. Tropical Cyclone Amanda was a category 4 on the Saffir-Simpson scale imaged by NASA's Aqua satellite.

NASA image from Jeff Schmaltz

Centuries ago European explorers learned the indigenous word hurakan, signifying evil spirits and weather gods, to describe the storms that battered their ships in the Caribbean. Today, "hurricane" is one of three names for giant, spiraling tropical storms with winds of at least 119 kilometers (74 miles) an hour.

Called hurricanes when they develop over the North Atlantic, central North Pacific, and eastern North Pacific, these rotating storms are known as cyclones when they form over the South Pacific and Indian Ocean, and typhoons when they develop in the Northwest Pacific.

Whatever the moniker, tropical cyclones can annihilate coastal areas and cause massive death tolls. Rated on the five-point Saffir-Simpson scale based on wind speed, hurricanes are considered major when they reach category 3. A category 5 storm can deliver wind speeds of more than 253 kilometers (157 miles) an hour.

The Atlantic Ocean's hurricane season peaks from mid-August to late October and averages five to six hurricanes per year. While cyclones on the northern Indian Ocean typically form between April and December, with peak storm activity around May and November.

How Are Hurricanes Formed?

Hurricanes begin as tropical disturbances in warm ocean waters with surface temperatures of at least 26.5 degrees Celsius (80 degrees Farenheit). Those low-pressure systems are fed by energy from warm seas.

A storm with wind speeds of 61 kilometers (38 miles) an hour or less is classified as a tropical depression. It becomes a tropical storm-and is given a name, according to conventions determined by the World Meteorological Organization-when its sustained wind speeds top 63 kilometers (39 miles) an hour.

Hurricanes are enormous heat engines that deliver energy on a staggering scale. They draw heat from warm, moist ocean air and release it through condensation of water vapor in thunderstorms.

Hurricanes spin around a low-pressure center known as the eye. Sinking air makes this 32- to 64-kilometer (20- to 40-mile)-wide area notoriously calm. But the eye is surrounded by a circular "eye wall" that contains the storm's strongest winds and rain.

Hurricane Dangers

Hurricanes bring destruction ashore in many different ways. When a hurricane makes landfall, it often produces a devastating storm surge-ocean water pushed ashore by wind-that can reach six meters (20 feet) high and move several kilometers inland.

Storm surges and flooding are the two most dangerous aspects of hurricanes, accounting for three-quarters of deaths from Atlantic tropical cyclones, according to a 2014 study. A third of the deaths from Hurricane Katrina, which made landfall off the coast of Louisiana in 2005 and killed approximately 1,200 people, were caused by drowning. Katrina is also the costliest hurricane on record, with damage totaling $125 billion.

A hurricane's high winds are destructive and may spawn tornadoes. Torrential rains cause further damage via flooding and landslides, which may occur many kilometers inland.

Although extremely potent storms have formed in the Atlantic, the most powerful tropical cyclones on record have formed in the Pacific, which gives storms more room to grow before they make landfall. Hurricane Patricia, which formed in the eastern Pacific off Guatemala in 2015, had the strongest winds recorded, at 346 kilometers (215 miles) an hour. The strongest Atlantic storm was Wilma in 2005, with winds of 294 kilometers (183 miles) an hour.

The best defense against a hurricane is an accurate forecast that gives people enough time to get out of the way. The United States National Hurricane Center issues hurricane watches for possible storms within 48 hours and hurricane warnings for expected storms within 36 hours.

Hurricanes and Climate Change

Climate change may be driving more frequent, more intense extreme weather, and that includes hurricanes. The 2018 hurricane season was one of the most active on record, with 22 major hurricanes in the Northern Hemisphere in under three months, and 2017 also saw seriously devastating Atlantic storms. While a number of factors determine a hurricane's strength and impact, warmer temperatures in certain locations play an important role. In the Atlantic, warming in the Arctic could drive future hurricane tracks farther west, making a U.S. landfall more likely.

Hurricane Harvey, which dropped a record-breaking 131.6 centimeters (51.8 inches) of rain on southeastern Texas in 2017, was fueled by surface waters in the Gulf of Mexico that were 1.11 degrees Celsius (2 degrees Fahrenheit) warmer than three decades before. A warmer atmosphere can also furnish more water vapor for making rain, as evaporation increases and warm air holds more vapor than cold.

Warming temperatures can also slow tropical cyclones, which can be a problem if their progression over land is extended, potentially increasing storm surges, rainfall, and exposure to high winds.

Potential trends make it more important than ever to be prepared for coming storms and to address the root causes of climate change, scientists say.

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Director

Tyson Brown, National Geographic Society

Production Managers

Gina Borgia, National Geographic Society

Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society, National Geographic Society

Margot Willis, National Geographic Society

other

Last Updated

October 19, 2023

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Hurricanes, Cyclones, and Typhoons Explained

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These giant, dangerous storms often cause substantial destruction.

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Weather - Hurricanes (Tropical Cyclones)

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Science >> Earth Science for Kids

Weather - Hurricanes (Tropical Cyclones)

What is a hurricane?

A hurricane is a large rotating storm with high speed winds that forms over warm waters in tropical areas. Hurricanes have sustained winds of at least 74 miles per hour and an area of low air pressure in the center called the eye.

Different Names for Hurricanes

The scientific name for a hurricane is a tropical cyclone. Tropical cyclones go by different names in different places. In North America and the Caribbean they are called "hurricanes", in the Indian Ocean they are called "cyclones", and in Southeast Asia they are called "typhoons."

How do hurricanes form?

Hurricanes form over the warm ocean water of the tropics. When warm moist air over the water rises, it is replaced by cooler air. The cooler air will then warm and start to rise. This cycle causes huge storm clouds to form. These storm clouds will begin to rotate with the spin of the Earth forming an organized system. If there is enough warm water, the cycle will continue and the storm clouds and wind speeds will grow causing a hurricane to form.

Parts of a Hurricane

Eye - At the center of the hurricane is the eye. The eye is an area of very low air pressure. There are generally no clouds in the eye and the wind is calm. Don't let this fool you, however, the most dangerous part of the storm is at the edge of the eye called the eye wall.

Eye wall - Around the outside of the eye is a wall made up of very heavy clouds. This is the most dangerous part of the hurricane and where the highest speed winds are. The winds at the eye wall can reach speeds of 155 miles per hour.

Rainbands - Hurricanes have large spirally bands of rain called rainbands. These bands can drop huge amounts of rainfall causing flooding when the hurricane hits land.

Diameter - Hurricanes can become huge storms. The diameter of the hurricane is measured from one side to the other. Hurricanes can span a diameter of over 600 miles.

Height - The storm clouds that power hurricanes can become very tall. A powerful hurricane can reach nine miles into the atmosphere.

The structure of a hurricane

Where do tropical cyclones occur?

Tropical cyclones occur over the ocean in areas near the equator. This is because there is plenty of warm water in these areas to allow the storms to form. There are seven major areas in the world that tend to produce tropical cyclones. See the map below.

Locations of tropical cyclones throughout the world

When do hurricanes occur?

Hurricanes that form in the Caribbean and the Atlantic Ocean occur between June 1st and November 30th each year. This is called hurricane season.

Why are hurricanes dangerous?

When hurricanes strike land they can cause huge amounts of damage. Most of the damage is caused by flooding and storm surge. Storm surge is when the ocean level rises at the coastline due to the power of the storm. Hurricanes also cause damage with high speed winds that can blow downtrees and damage homes. Many hurricanes can develop several small tornados as well.

How are they named?

Hurricanes in the Atlantic are named based on a list of names maintained by the World Meteorological Organization. The names go in alphabetical order and the storms are named as they appear. So the first storm of the year will always have a name that starts with the letter "A." There are six lists of names and each year a new list is used.

Categories

Tropical cyclones are categorized according to the speed of sustained winds.

Tropical Depression - 38 mph or less

Tropical Storm - 39 to 73 mph

Hurricane

Category 1 - 74 to 95 mph

Category 2 - 96 to 110 mph

Category 3 - 111 to 129 mph

Category 4 - 130 to 156 mph

Category 5 - 157 or higher mph

Interesting Facts about Hurricanes

Hurricanes rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. This is due to the rotation of the Earth called the Coriolis effect.

The letters Q, U, X, Y, and Z are not used for the first letter when naming hurricanes.

The names are alternated between boy and girl names.

Weather forecasters draw a cone showing where they think the hurricane is most likely to travel.

You can always find out the latest information on hurricanes at the website of the National Hurricane Center which tracks and forecasts hurricanes.

Activities

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Earth Science Subjects

Science >> Earth Science for Kids

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Kids learn about hurricanes (Tropical Cyclones) including how they form, names, eye, eye wall, rainbands, locations, seasons, facts, and categories.

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Hold on tight, gang - and we mean super tight! - because we're about to check out ten facts on one of nature's most powerful forces - hurricanes!

1. Hurricanes are giant tropical storms that produce heavy rainfall and super-strong winds.

2. Hurricanes form over warm ocean waters near the equator. The warm, moist air above the ocean surface rises, causing air from surrounding areas to be "sucked" in. This "new" air then becomes warm and moist, and rises, too, beginning a continuous cycle that forms clouds. The clouds then rotate with the spin of the Earth. If there is enough warm water to feed the storm, a hurricane forms!

3. Hurricanes rotate around a circular centre called the " eye ", where it is generally calm with no clouds. Surrounding the eye is the eye wall - the most dangerous part of the hurricane with the strongest winds, thickest clouds and heaviest rain!

4. Most hurricanes occur harmlessly out at sea. However, when they move towards land they can be incredibly dangerous and cause serious damage.

5. The strong spiraling winds of a hurricane can reach speeds of up to 320kmph - strong enough to rip up entire trees and destroy buildings!

6. In the southern hemisphere, hurricanes rotate in a clockwise direction, and in the northern hemisphere they rotate in an anti-clockwise direction. This is due to what's called the Coriolis Force, produced by the Earth's rotation.

7. When a hurricane reaches land it often produces a " storm surge". This is when the high winds drive the sea toward the shore, causing water levels to rise and creating large crashing waves. Storm surges can reach 6m high and extend to over 150km!

8. Hurricanes are also called cyclones and typhoons, depending on where they occur. In the Atlantic Ocean and Northwest Pacific they are hurricanes, in the Northwest Pacific they are typhoons and in the South Pacific and Indian Ocean they are cyclones.

9. The largest hurricane on record is Typhoon Tip, which occurred in 1979 in the northwest Pacific. With a diameter of around 2,220km, it was nearly half the size of the United States!

10. Hurricanes are given names by the World Meteorological Organisation (WMO) so that they can be distinguished. Each year, tropical storms are named in alphabetical order according to a list produced by the WMO. That name stays with the storm if it develops into a hurricane. The names can only be repeated after six years.

Photos: Getty Images UK

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10 Facts about Hurricanes! - National Geographic Kids

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Check out ten top facts about hurricanes here at National Geographic Kids! Learn how hurricanes form, what the world's biggest hurricane is and more!

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How Do Hurricanes Form? | NASA Space Place – NASA Science for Kids

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Is it a Hurricane Typhoon or Cyclone? 🌀 Nature Earth Science

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Hurricane formation model | Hurricane Weather Diorama | Science fair project | school project

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Hurricanes: Science and Society: Featured Storms

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What is a hurricane?A hurricane is a huge storm! It can be up to 600 miles across and have strong winds spiraling inward and upward at speeds of 75 to 200 mph. Each hurricane usually lasts for over a week, moving 10-20 miles per hour over the open ocean. Hurricanes gather heat and energy through contact with warm ocean waters. Evaporation from the seawater increases their power. Hurricanes rotate in a counter-clockwise direction around an “eye” in the Northern Hemisphere and clockwise direction in the Southern Hemisphere. The center of the storm or “eye” is the calmest part. It has only light winds and fair weather. When they come onto land, the heavy rain, strong winds and large waves can damage buildings, trees and cars.

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Words to Know Am I at Risk? What Can I Do? Learn More

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Hurricanes are severe tropical storms that form in the southern Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern Pacific Ocean. They collect heat and energy through contact with warm ocean waters and then move toward land. Evaporation from the ocean water increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye," which is the center of the hurricane.

Hurricanes have winds at least 74 miles per hour. When hurricanes come onto land, their heavy rain, strong winds, and large waves can damage buildings, trees, and cars. Storm surge is when rising water moves inland, or away from the coastline. It's very dangerous.

Words to Know

Inland - Away from the coastline.

Am I at Risk?

What Can I Do?

Before

During

After

Learn More

Did you know?

Hurricanes can also affect areas greater than 100 miles away from the coastline. People who live inland are also at risk for wind, thunderstorms, tornadoes, and flooding.

Helpful Links

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Words to Know Am I at Risk? What Can I Do? Learn More

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Kids learn about tsunamis including what causes them such as earthquakes, where they occur, why they are dangerous, and what happens during a tsunami event.

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Easy Science for Kids World’s Biggest Tsunamis - learn fun facts about animals, the human body, our planet and much more. Fun free World’s Biggest Tsunamis activities!

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What is a tsunami?A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. Tsunamis are NOT tidal waves. Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water. With typical waves, water flows in circles, but with a tsunami, water flows straight. This is why tsunamis cause so much damage!How are tsunamis generated?Tsunamis are generated by any large, impulsive displacement of the sea level. The most common cause of a tsunami is sea floor uplift associated with an earthquake. Tsunamis are also triggered by landslides into or under the water surface, and can be generated by volcanic activity and meteorite impacts.How often do tsunamis occur?On the average, two tsunamis occur per year throughout the world which inflict damage near the source. Approximately every 15 years a destructive, ocean-wide tsunami occurs.Can strike-slip (horizontal motion) earthquakes trigger tsunamis?Yes, approximately 10-15% of damaging tsunamis are triggered by strike-slip earthquakes. This type of earthquake is less likely to trigger a tsunami than one with vertical motion. The waves are likely generated by associated landslides or motion of a sloping bathymetric feature. Tsunamis generated by strike-slip earthquakes normally affect regions near the source only.What does the word “tsunami” mean?Tsunami (soo-NAH-mee) is a Japanese word meaning harbor wave.How fast do tsunamis travel?Tsunami velocity depends on the depth of water through which it travels. Velocity equals the square root of the product of the water depth times the acceleration of gravity. Tsunamis travel approximately 475 mph in 15,000 feet of water. In 100 feet of water the velocity drops to about 40 mph.Did you know…A tsunami travels from the central Aleutian Islands to Hawaii in about 5 hours and to California in about 6 hours, or from the Portugal coast to North Carolina in about 8.5 hours.

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They can speed across the ocean as fast as a jet plane, swallow up islands and wipe out villages.

But what causes tsuamis...? Join National Geographic Kids and dive into our tsunami facts to find out!

What causes a tsunami?

Meaning " great harbour wave" in Japanese, tsunamis are sometimes called "tidal waves" but their strength has nothing to do with the tides. About four out of five tsunamis happen within the Ring Of Fire, a zone in the Pacific Ocean where earthquakes and volcanic eruptions frequently take place.

Giant slabs of the Earth's crust, called tectonic plates, grind together. Sometimes, though, the plates get stuck, the pressure builds up and they suddenly slam into a new position. This causes an earthquake. If an earthquake lifts or drops part of the ocean floor, the water above rises and starts spreading across the ocean, causing a tsunami. Underwater landslides or volcanic eruptions can also displace water (cause water to spread across the ocean) and may lead to a tsunami.

How big is a tsunami?

Out in the open ocean, tsunami waves are only about one-metre high because the water is deep. However, as the water becomes shallow, the waves slow down and begin to grow. They can rise 35m or higher - that's the same as a 10-floor block of flats! However, the scariest thing about a tsunami is its wavelength, as this determines how far inland it can travel. Whereas a large wave caused by a storm might have a wavelength of up to 150m, a tsunami could reach up to a fearsome 1,000km!

How fast is a tsunami?

A normal wind wave travels at about 90kmh, but a tsunami can race across the ocean at an incredible 970kmh! Sometimes, before a tsunami hits, there is a huge vacuum effect, sucking water from harbours and beaches. People can see the ocean floor littered with flopping fish and other sea animals. Then a wave blasts onto the shore minutes later, then another and another for two hours or more. There may also be up to one hour between each wave.

Can you predict when a tsunami is coming?

To save lives, scientists established the Pacific Tsunami Warning System, based in Hawaii, in the USA. Its network of detectors can track quakes that may cause a tsunami. These waves can race from one side of the Pacific Ocean to the other in less than a day, so people need to be warned in time to head for higher ground!

What do you think of these tsunami facts? Let us know by leaving a comment, below!

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Tsunami facts: check out the mighty wave! - National Geographic Kids

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Check out these epic tsunami facts from National Geographic Kids! How do tsunamis form? And how big are they? Find out all about them in our tsunami facts...

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Tsunami Facts for Kids - What causes a Tsunami - What is a Tsunami for Kids? - Tsunami Facts Tsunami

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Tsunami | The Dr. Binocs Show | Educational Videos For Kids

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What Is An Earthquake? | The Dr. Binocs Show | Educational Videos For Kids

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You feel the ground suddenly shake, and nearby objects are trembling. An earthquake is happening.

Also called a temblor, an earthquake is caused by the movement of parts of the Earth's crust, its outermost layer. They happen millions of times a year, but most are so small people don't even feel them.

But powerful earthquakes can cause landslides, tsunamis, flooding, and other dangerous events. Most damage and deaths happen in places where a lot of people live, because the shaking causes windows to break, structures to collapse, fire to break out, and other dangers.

Learn more about these unpredictable Earth tremors-and what to do if one rattles near you.

How earthquakes develop

The action all starts thousands of miles below your feet.

Picture Earth as a hard-boiled egg: Earth's core is the yolk, and the mantle is the white part. The outer crust is the eggshell.

People live on the surface of the crust. Below the surface-but still within the crust-are tectonic plates. Like gigantic puzzle pieces, these huge slabs of rock encircle the Earth. The seven major plates are named for the regions they rest under: the African, Antarctic, Eurasian, Indo-Australian, North American, Pacific, and South American tectonic plates

Tectonic plates aren't connected but are close together. Where they meet along their edges is called a fault. When heat from the Earth's core creates currents in the crust, the tectonic plates can scrape, bump, or drag along each other. This is what causes an earthquake-and why the surface sometimes cracks like an eggshell.

How to measure earthquakes

About a half-million quakes rock the Earth every day. Usually the quake is too small, too far below the surface, or too deep in the seafloor to be felt. Some, however, are so powerful they can be felt thousands of miles away.

The spot on the surface just above where an earthquake starts is called the epicenter. Ripples called seismic waves travel out from the epicenter. This causes vibrations that people can feel, sometimes very far from the epicenter.

How far away people can feel an earthquake's vibrations depends on its size, or magnitude. Scientists base the magnitude on the strength and duration of the quake's seismic waves. The higher the number, the more powerful the earthquake: A magnitude 3 to 4.9 earthquake is considered minor; 5 to 6.9 is moderate to strong; 7 to 7.9 is major; and 8 or more is an extremely powerful temblor.

As the crust settles after an earthquake, another temblor called an aftershock can happen. Usually, aftershocks are not as powerful as the first quake but can still be very strong.

Geologists can't predict earthquakes. But they're working to change that with new research and technology.

Where earthquakes happen

Earthquakes occur along faults, the areas where tectonic plates meet. About 80 percent of earthquakes occur along the rim of the Pacific Ocean. Called the Ring of Fire because of the large number of volcanoes there, the area is a meeting point for many tectonic plates.

Earthquakes are also common in California because the region sits on top of the Pacific and North American tectonic plates. Temblors happen when these two plates grind against each other. About two-thirds of this movement happens along the San Andreas Fault.

Another major earthquake area in the United States is the New Madrid Seismic Zone, which affects Missouri, Arkansas, Tennessee, Kentucky, and Illinois.

How to survive an earthquake

Earthquakes can happen anytime or anywhere-even if you don't live near a fault. So it's a good idea to prepare.

* Talk with your family about the safest places in your home in case an earthquake hits. This could be under a sturdy table or next to an interior wall (one that is not connected to the outside).

* Look for heavy items that could fall or break during a quake, and move them to safer spots.

* Ask your parents to make sure you have an emergency kit containing things like first-aid supplies, a flashlight, a cell phone charger, and a battery-operated radio. Your family should also have enough food and water for at least 72 hours

DURING AN EARTHQUAKE: Most earthquakes last only 10 to 30 seconds, so it's important to get to a safe place fast. Remember three things during an earthquake: drop, cover, and hold on.

Drop: Get down on your hands and knees and crawl to your shelter.

Cover: Underneath a sturdy table, desk, or bed, cover your head and neck with your arms. If furniture isn't nearby, crouch down on your knees with your arms over your head and neck next to an interior wall. (Don't stand under a doorway-they can easily collapse.)

Hold on: If you're under a piece of furniture, hold on with one hand and move with the furniture if it starts sliding. Stay where you are until the shaking stops.

AFTER AN EARTHQUAKE: Once the earthquake ends, check for injuries. Listen to a radio for any warnings and instructions from official organizations like the United States Geological Survey. Be prepared for any aftershocks.

Text and images adapted from Everything Volcanoes and Earthquakes: Earthshaking photos, facts, and fun!

(Learn more about earthquakes at National Geographic.)

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Learn the science behind how earthquakes happen-and how you can stay safe if one hits.

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An earthquake is an intense shaking of Earth's surface. The shaking is caused by movements in Earth's outermost layer.

Why Do Earthquakes Happen?

Although the Earth looks like a pretty solid place from the surface, it's actually extremely active just below the surface. The Earth is made of four basic layers: a solid crust, a hot, nearly solid mantle, a liquid outer core and a solid inner core.

The solid crust and top, stiff layer of the mantle make up a region called the lithosphere. The lithosphere isn't a continuous piece that wraps around the whole Earth like an eggshell. It's actually made up of giant puzzle pieces called tectonic plates. Tectonic plates are constantly shifting as they drift around on the viscous, or slowly flowing, mantle layer below.

This non-stop movement causes stress on Earth's crust. When the stresses get too large, it leads to cracks called faults. When tectonic plates move, it also causes movements at the faults. An earthquake is the sudden movement of Earth's crust at a fault line.

The location where an earthquake begins is called the epicenter. An earthquake's most intense shaking is often felt near the epicenter. However, the vibrations from an earthquake can still be felt and detected hundreds, or even thousands of miles away from the epicenter.

How Do We Measure Earthquakes?

The energy from an earthquake travels through Earth in vibrations called seismic waves. Scientists can measure these seismic waves on instruments called seismometer. A seismometer detects seismic waves below the instrument and records them as a series of zig-zags.

Scientists can determine the time, location and intensity of an earthquake from the information recorded by a seismometer. This record also provides information about the rocks the seismic waves traveled through.

Do Earthquakes Only Happen on Earth?

Earthquake is a name for seismic activity on Earth, but Earth isn't the only place with seismic activity. Scientists have measured quakes on Earth's Moon, and see evidence for seismic activity on Mars, Venus and several moons of Jupiter, too!

NASA's InSight mission took a seismometer to Mars to study seismic activity there, known as marsquakes. On Earth, we know that different materials vibrate in different ways. By studying the vibrations from marsquakes, scientists hope to figure out what materials are found on the inside of Mars.

InSight is collecting tons of information about what Mars is like under the surface. These new discoveries will help us understand more about how planets like Mars-and our home, Earth-came to be.

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Learn more about tremors on Earth-and other planets too!

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Earthquakes

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Kid's learn about the science of earthquakes. What causes them and where they happen.

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How To Survive An Earthquake? |  Earthquake Safety Tips | The Dr Binocs Show | Peekaboo Kidz

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Save the Children provides earthquake relief to children in the U.S. and around the world. Wondering what to if there is an earthquake? Start here.

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Blizzard | Kid-Friendly Facts About Blizzard | Weather Wiki

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Blizzards are extremely dangerous winter storms with intense winds and blowing snow. Read through this wiki page to learn more about what a blizzard actually is, how and why they occur, and even some fun kid-friendly facts about blizzards.

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The temperature outside is below freezing, the winds are howling, and you can barely see the tree in your front yard. A large amount of snow has been falling for more than three hours-a blizzard is under way.

According to the National Weather Service, blizzards are snowstorms with winds higher than 35 miles an hour and visibility (meaning, how far you can see) of less than a quarter mile. Winds from a blizzard can travel over 120 miles an hour-that's faster than a cheetah, the world's fastest land animal.

These conditions can be dangerous-low visibility can cause drivers to crash on roads, and high winds can topple power lines, which means some homes will be without heat. Large amounts of snowfall can trap people inside their homes. And those stuck outside in freezing temperatures can face frostbite or hypothermia, a condition in which your body temperature becomes dangerously low.

Learn more about these dangerous winter storms-and what to do if one comes your way.

How blizzards develop

Before you can have a blizzard, you first need snow. And for snow, you need clouds.

Clouds form when part of the air becomes cold enough that water vapor, which is the gas form of water, condenses and becomes tiny water droplets that form around things like dust and sea salt. When those droplets collect more water, they fall as rain. At temperatures between about minus 40°F and 32°F, the water droplets crystallize. When enough crystals stick together, they form snowflakes and fall to the ground.

What makes a snowstorm a blizzard is strong wind. First, warm air from the Equator mixes with cold air from the Arctic. Wind forms when warm air rises over the cold air; the faster the warm air rises over the cold air, the stronger the wind becomes.

Another type of winter storm is called a ground blizzard. This is when gusty winds-often 50 to 60 miles an hour-lift up snow that's already on the ground. Both types of blizzards can cause whiteouts, a condition in which so much snow is blowing so fast that it's hard to see anything. Sometimes you can't even tell the difference between the sky and the ground!

Blizzards in the future

Blizzards occur all over the world. But because they're closer to the Arctic, places like Russia, central and northeastern Asia, northern Europe, Canada, and the northern United States experience more blizzards than other parts of the globe.

And though most blizzards occur during winter, they can happen during other seasons, too. One of the most severe blizzards in the United States-known as the Great Blizzard of '88-happened in March 1888, killing more than 400 people.

Scientists believe that as global temperatures continue to rise because of climate change, blizzards could become more extreme. A warmer atmosphere means more moisture in the air that will eventually fall as snow (or rain); many also believe that warmer temperatures will create higher winds.

How to survive a blizzard

The best way to survive a blizzard is to prepare for extreme weather. Meteorologists use certain words and phrases that will help you know when a blizzard is coming. For instance:

Wind chill factor: This is what the temperature feels like outside, even if the real temperature is higher. Blizzards usually have wind chill factors of 10°F or lower.
Winter storm outlook or watch: This means that conditions are right for a snowstorm or blizzard to form.
Winter weather advisory: This means that dangerous winter weather is happening, which could be a blizzard.

Learn more about ways you can protect your family from dangerous winter weather.
Before a blizzard:
* Ask your parents to "winterize" your house: Check that heating sources are clean and working, and make sure windows are insulated so cold air can't come in. (If they're not, apply plastic sheets on the inside.)
* If you have a fireplace, stock up on firewood or coal.
* Make sure your family has a home emergency kit: water (at least a gallon for each person per day for several days), food (non-perishable or canned items for several days), flashlight, extra batteries, first-aid kit, manual can opener, local maps, battery-powered radio, and cell phone with a backup battery.
* Charge devices like cell phones.
During a blizzard:
* Listen to local radio or news for updated weather information.
* Layer up if you lose power. Try a t-shirt under a long-sleeved shirt under a sweater under a coat. That way you can take off items if you start to sweat. (Being cold and wet will just make you colder!) Other must-haves: two pairs of socks, mittens instead of gloves, a thick scarf, and a hat.
* Drink lots of water-or hot cocoa, or tea, or whatever-to stay hydrated. You might not think you need as much liquid in the winter as you do in summer, but staying hydrated helps your body generate enough heat to maintain a healthy body temperature.
* Evacuate only if you lose power and your home becomes too cold to stay in. Try to find a shelter-like a nearby school or library-that has heat and electricity.
If you must leave your house:
* Try to travel during the day when visibility will be better.
* Load up on blankets, canned fruits, bottles of water, and warm fluids in a thermos; bring an external battery in case you need to recharge your cell phone.
* Don't forget the layers!
* If you get stuck in your car, huddle with your companions for extra warmth.
* If you're caught outside, huddle together against a tree or a rock ledge to block the wind, and do not sit down on snow. (Your non-frozen butt will thank you.) And don't eat the snow-that could dangerously lower your body temperature.
* If you or your companions show signs of hypothermia or frostbite (shivering, feeling very tired, confusion, drowsiness, memory loss, slurred speech), seek help immediately.

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Learn how these winter snowstorms form-and how you can stay safe if one blows your way.

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A blizzard is a severe snowstorm. It brings low temperatures, strong winds, and a lot of blowing snow. Blizzards start when a high pressure system touches a low pressure system.

The word blizzard is sometimes used incorrectly by news media to talk about big winter storms, even if the storm is not a blizzard.

The difference between a blizzard and a snowstorm is the strength of the wind, not the amount of snow. To be a blizzard, a snow storm must have sustained winds or frequent gusts that are greater than or equal to 56 km/h (35 mph) with blowing or drifting snow which reduces visibility to 400 m or 0.25 mi or less and must last for a prolonged period of time-typically three hours or more.

Some areas are more likely to be hit by blizzards than others, but a blizzard can occur in any place where snow falls. In North America, blizzards happen often in the northern-east states, and in the provinces of Canada. In this region, blizzards can happen more than twice each winter.

They also occur often in the mountain ranges of western North America. Because these regions have low populations, blizzards sometimes are not reported.

A very dangerous type of blizzard is a whiteout. In a whiteout, downdrafts and snowfall are so thick that people cannot tell the ground and sky apart. People caught in a whiteout lose their sense of direction very fast. This is a large danger to pilots when they are flying airplanes, because they cannot tell how close they are to the ground, and may crash.

Who cleans up after blizzards?

The community cleans up after a snowstorm/blizzard occurs. Blizzards only usually go for 3 hours so everything won't be too damaged, meaning it won't be as hard as an earthquake or tsunami to clean.

How deep the snow gets

These horrible blizzards can achieve up to 25-30 feet deep. A basketball hoop is 10 ft high, so a blizzard can get snow as deep as the height of two or three hoops.

How do blizzards occur?

Firstly you need cold enough air to cause snow to fall in the clouds and ground level water and moisture is needed to form clouds and precipitation. The moisture is called water vapour to make the clouds a source of water vapour is cold air blowing across large lakes or the sea but the cold air doesn't actually make too much snow, its a combination of cold and warm air that does it. The warm air normally meets the cold air if the wind is being pulled towards the equator when they are brought together a front is formed and precipitation is formed and the warm air can go up to the clouds and the blizzard forms from there.

How strong are a blizzard's winds?

There is sustained wind or frequent gusts of 35 miles per hour or greater.

How cold can blizzards get?

Blizzards can get down to -12 degrees or lower. This makes it fairly easy to get hypothermia in a blizzard. Mostly freezing electrics and machinery making life very hard in the Hypothermic temperatures.

A blizzard brings strong winds that can cause power outages, damage property and disrupt emergency communication. As a result, people can end up without food and water supply.

Blizzards are dangerous as they may lead to injuries and even deaths on the road due to low visibility.

You should avoid being caught outdoors in a blizzard as skin left exposed to such severe conditions could lose all sensitivity within minutes. As a result, you can suffer from hypothermia and frostbite. In extreme cases it may lead to death.

Blizzards may negatively affect the environment, killing plants and animals that other species rely on in their food chain. This forces some animals to find alternative means of getting food or die if food is scarce.

Blizzards impact accumulation of water vapor in the atmosphere, which then leads to greater precipitation throughout the year.

Famous U.S. blizzards

The Great Blizzard of 1888 was very damaging for the Northeastern United States. In that blizzard, 400 people died, 200 ships sunk, and snowdrifts were 10 or 15 feet high. In the Great Plains, states were hit by the Schoolhouse Blizzard that trapped children in schools and killed 235 people.

In 1880-1881 there was a winter that people in the Dakotas called the "Hard Winter". The author Laura Ingalls Wilder wrote her book The Long Winter about that winter's story. It talks about one blizzard after another, and how it changed Laura's family and everybody around her. The book is almost all true. Her story of two men from the town of DeSmet, South Dakota, going after some wheat stored some miles south of DeSmet in February 1881 is true, and Ingalls later married one of the men, Almanzo Wilder. If the two men had not found and brought back the wheat, the people would have starved. The snow and ice thawed in April, and the railroads could start again. The train picture above was photographed on March 29, 1881, not far from DeSmet.

34 people died during a 3-day spring blizzard on March 1920 in North Dakota. One of the people who died was Hazel Miner, a teenage girl who died of freezing to death when she got lost on her way home from her one-room-school.

The Armistice Day Blizzard in 1940 surprised many people with how fast the temperature dropped. It was 60 °F (15.6 °C) in the morning, but by noon, it was snowing. Some of the people froze to death in the snow. 154 people died in the Armistice Day Blizzard.

105 years after the Great Blizzard of 1888, a giant blizzard, named the Storm of the Century, hit the U.S in 1993. It dropped snow on 26 states and reached as far north as Canada and as far south as Mexico. In many southern U.S. areas, such as parts of Alabama, more snow fell in this storm than ever fell in an entire winter. Highways and airports closed across the U.S. The blizzard also made 15 tornadoes in Florida. When the storm was over, 270 people died and 48 were reported missing.

Other famous blizzards

Related pages

Images for kids

Blizzard into Tochal Skiing resort, Tehran and involved skiers.

Conditions approaching a blizzard whiteout in Minnesota, on March 1, 2007. Note the unclear horizon near the center.

Stereoscopic view card showing "Blasting ice with dynamite from in front of steamer on the ways, by Stanley J. Morrow" ~ A view of Yankton's riverfront after the flood of March 1881.

In Spanish: Ventisca para niños

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Nor'easters can occur in the eastern United States any time between October and April, when moisture and cold air are plentiful. A Nor'easter is named for the winds that blow in from the northeast and drive the storm up the east coast along the Gulf Stream, a band of warm water that lies off the Atlantic coast. They are known for dumping heavy amounts of rain and snow, producing hurricane-force winds, and creating high surfs that cause severe beach erosion and coastal flooding. Winter Storms

How do winter storms form?
Winter storms derive their energy from the clash of two air masses of different temperatures and moisture levels. Winter storms usually form when an air mass of cold, dry, Canadian air moves south and interacts with a warm, moist air mass moving north from the Gulf of Mexico. The point where these two air masses meet is called a front. If cold air advances and pushes away the warm air, it forms a cold front. When warm air advances, it rides up over the denser, cold air mass to form a warm front. If neither air mass advances, it forms a stationary front.

What are snowflakes?
Snowflakes are made of ice crystals. Each snowflake is six-sided and made of as many as 200 ice crystals. Snowflakes form in clouds where the temperature is below freezing. The ice crystals form around tiny bits of dirt that has been carried up into the atmosphere by the wind. As the snow crystals grow, they become heavier and fall toward the ground. Why is snow white?
Bright snow blinds us with its gleaming white color because it reflects beams of white light. Instead of absorbing light, snow's complex structure prevents the light from shining through its lattice formation. A beam of white sunlight entering a snow bank is so quickly scattered by a zillion ice crystals and air pockets that most of the light comes bouncing right back out of the snow bank. What little sunlight is absorbed by snow is absorbed equally over the wavelengths of visible light thus giving snow its white appearance. So while many natural objects get their blue, red, and yellow colors from absorbing light, snow is stuck with its white color because it reflects light.

What is thundersnow? How is snow formed?
Snow is commonly formed when water vapor undergoes deposition, which is when water vapor changes directly to ice without first becoming a liquid, high in the atmosphere at a temperature of less than 32°F and then falls to the ground. What is sleet?
Sleet is just rain drops that freeze into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. However, it can accumulate like snow and cause a hazard to motorists.
What is an ice storm?
An ice storm is a type of winter storm caused by freezing rain. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25-inch of ice on exposed surfaces.
What is freezing rain?
Freezing rain is just rain that falls onto a surface with a temperature below freezing. This causes it to freeze to surfaces, such as trees, cars, and roads, forming a coating or glaze of ice. Even small accumulations of ice can cause a significant hazard. How do ice storms form?
Ice storms form when a layer of warm air is between two layers of cold air. Frozen precipitation melts while falling into the warm air layer, and then proceeds to refreeze in the cold layer above the ground. This creates freezing rain or a glaze of ice.

What is frost? What is a frost quake?
Frost is white ice crystals that form on a surface, like the ground or leaves of a plant. Frost is created when the air temperature drops below freezing and the water vapor in the air freezes into ice crystals.

How is lake-effect snow formed?
As the cold air flows over the warm lake water, the relatively warm water heats the air's bottom layer as lake moisture evaporates into the cold air. Since warm air is lighter or less dense than cold air, the heated air rises and begins to cool. As the air cools, the moisture that evaporated into it condenses and forms clouds and snow begins falling from the cloud if the air is humid enough. (Graphic Credit: USA TODAY.) What is a Nor'easter?

What is Wind Chill? What is an Alberta Clipper? Click Here to calculate the Wind Chill.
An Alberta clipper is an area of low pressure that generally forms over Alberta, Canada, east of the Rocky Mountains. They develop east of the Rockies because air flowing eastward over the mountains creates favorable conditions. Once an Alberta Clipper forms it usually moves very rapidly to the southeast across the USA's northern Plains and then to the east off the mid-Atlantic Coast. Clippers usually cause only light precipitation with very few producing major snowstorms. However, if conditions are favorable, some Alberta clippers can rapidly intensify off the East Coast once the storm taps the relatively warm moist air over the Atlantic Ocean. The storms that rapidly intensify sometimes spread heavy snow over New England and southeastern Canada. Generally, the main weather features associated with Alberta clippers are some light snow and a reinforcement of cold air over the USA.
What is frostbite? How do blizzards form?

A blizzard is a long-lasting snowstorm with very strong winds and intense snowfall. You need three things to have a blizzard; cold air at the surface, lots of moisture, and lift. Warm air must rise over cold air.
What is an avalanche?
An avalanche is a moving mass of snow that may contain ice, soil, rocks, and uprooted trees. The height of a mountain, the steepness of its slope, and the type of snow lying on it all help determine the likelihood of an avalanche. Avalanches begin when an unstable mass of snow breaks away from a mountainside and moves downhill. The growing river of snow picks up speed as it rushes down the mountain. Avalanches have been known to reach speeds of 245 miles an hour (394 kilometers per hour)—about four times as fast as the speediest downhill skier.
Click Here to learn more about Avalanche Saftey.
Know the Lingo
WINTER WEATHER ADVISORIES - Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life-threatening situations.

Thundersnow is when thunder and lighting occur during a snowstorm. This occurs most often in late winter or early spring. To get thundersnow, you need a mass of cold air on top of warm air, plus moist air closer to the ground. Thundersnow starts out like a summer thunderstorm. The sun heats the ground and pushes masses of warm, moist air upward, creating unstable air columns. As it rises, the moisture condenses to form clouds, which are jostled by internal turbulence. The "tricky part" for making thundersnow is creating that atmospheric instability in the wintertime. For thundersnow to occur, the air layer closer to the ground has to be warmer than the layers above, but still cold enough to create snow. During thundersnow events, heavy snowfall is to be expected. In some cases, two inches per hour is possible.

Click Here to see if there are any active warnings in your area.

Winter Storm Safety Tips
BEFORE A WINTER STORM: Have a disaster plan and prepare a disaster supplies kit for your home and car. Include a first aid kit, emergency food supply, bottled water, battery-operated radio, flashlight, protective clothing, and blankets. Don't forget, be aware of changing weather. DURING A WINTER STORM: Stay indoors and dress warmly. Eat regularly, because food provides the body with energy for producing its own heat. Also, drink lots of water. If you must go outside, wear layered clothing, mittens and a hat. Watch for signs of hypothermia and frostbite. Remember to keep dry. Always change wet clothing to prevent the loss of body heat. If you must drive, carry a cell phone. Always, keep the gas tank full. Don't forget, let someone know where you're going, just in case your car gets stuck. If you're car gets stuck, stay with it and wait for help unless help is visible within 100 yards. Use maps and car mats to stay warm.

AFTER A WINTER STORM: Avoid driving until conditions have improved. Avoid overexertion! Heart attacks from shoveling snow are the leading cause of deaths during the winter. Also, check on neighbors to make sure they're okay.

Frost quakes are non-tectonic seismic events, meaning they are not caused by the shifting of the Earth's tectonic plates. Also known as cryoseisms, frost quakes are caused by a sudden rapid freezing of ground and bedrock, usually when temperatures go from above freezing to below zero. As moisture absorbed in the rock and soil freezes, it expands. This puts a great amount of stress on the areas around it. Eventually, the stress is too much and the soil and rock will crack in an "explosive" manner, creating a loud sound and even shaking the ground surface. Since temperatures are coldest in the overnight hours, most people experience frost quakes in the middle of the night. Winter Storm Activities
Lesson Plan: Here is a great lesson plan on learning about winter weather. In this activity, kids investigate aspects of winter weather, such as temperature and wind. They familiarize themselves with weather-related words. It's a great activity for K-2nd graders.

Cold air moves over warm water and is warmed from below. Moisture evaporates in the air.

Warm moist air rises downwind of lakes and forms heavy snow.

Lesson Plan: Here is a great lesson plan on learning about winter weather. In this activity, kids learn how winter storms form and about the different types of fronts. It's a great activity for 3rd-5th graders. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.
Measuring Snow Experiment: Here is a great experiment that lets kids measure snow. They let the snow melt and then measure it again. It teaches kids that snow is very dense and is why it holds more space than water.

The wind chill is the temperature your body feels when the air temperature is combined with the wind speed. The higher the wind speed the faster exposed areas of your body lose heat and the colder you feel.Melting Snow Experiment: Here is another experiment that teaches kids the difference between the freezing and melting process. It allows kids to take the temperature of a glass of snow. Then, watch the snow melt and observe how the temperature changed.

Frost Experiment: Here is a great experiment that lets kids make frost. They can see how dew turns into frost in a matter of minutes.Examining Snowflakes Experiment: Here is a great experiment that lets kids see snowflakes up close. They can examine the snowflake's six sides.
Pressure Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!
Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.
Make A Barometer Experiment: Here is an experiment that allows the kids to make a barometer.

Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

Frostbite is damage to the skin due to prolonged exposure to cold temperatures, usually below 32° F.

WINTER STORM WATCH - Alerts the public to the possibility of a blizzard, heavy snow, heavy freezing rain, or heavy sleet. Winter Storm Watches are usually issued 12 to 48 hours before the beginning of a winter storm.

WINTER STORM WARNING - Issued when hazardous winter weather in the form of heavy snow, heavy freezing rain, or heavy sleet is occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected.

BLIZZARD WARNING - Issued for sustained or gusty winds of 35 mph or more, and falling or blowing snow creating visibilities at or below 1/4 mile. These conditions should persist for 3 hours.

FROST/FREEZE WARNING - Issued when below freezing temperatures are expected.

LAKE EFFECT SNOW ADVISORY - Issued when accumulation of lake effect snow will cause significant inconvenience.

LAKE EFFECT SNOW WARNING - Issued when heavy lake effect snow is occurring.

WIND CHILL ADVISORY - Issued when the wind chill temperature is forecast to be between -15°F to -24°F.

WIND CHILL WARNING - Issued when the wind chill temperature is forecast to be -25°F or lower.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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What is a Blizzard? | Winter Science | Weather Science | SciShow Kids

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What Are Winter Storms? | How to Survive a Winter Storm? | What is a Blizzard? | Dr. Binocs Show

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Each winter, hundreds are injured or killed by exposure to cold, vehicle accidents, and fires. Learn what to do stay safe during blizzards and other winter storms!

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US Department of Commerce, NOAA, National Weather Service

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Prepare! Don’t Let a Winter Storm Take You by Surprise

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Prepare! Don’t Let a Winter Storm Take You by Surprise

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During an avalanche, a mass of snow, rock, ice, soil, and other material slides swiftly down a mountainside. Avalanches of rocks or soil are often called landslides. Snowslides, the most common kind of avalanche, can sweep downhill faster than the fastest skier.

A snow avalanche begins when an unstable mass of snow breaks away from a slope. The snow picks up speed as it moves downhill, producing a river of snow and a cloud of icy particles that rises high into the air. The moving mass picks up even more snow as it rushes downhill. A large, fully developed avalanche can weigh as much as a million tons. It can travel faster than 320 kilometers per hour (200 miles per hour).

Avalanches occur as layers in a snowpack slide off. A snowpack is simply layers of snow that build up in an area, such as the side of a mountain. In winter, repeated snowfalls build a snowpack dozens of meters thick. The layers vary in thickness and texture.

The bonds between the layers of a snowpack may be weak. Melted snow that refreezes may cause a slick coating of ice to form on the surface of a layer. A new snowfall may not stick to this slippery layer, and it may slide off. During spring thaw, melted snow can seep through a snowpack, making the surface of a lower layer slippery. Added weight or vibration can easily send the top layers of a snowpack hurtling downhill.

Sluffs and Slabs

There are two main types of snow avalanches-sluffs and slabs. Sluff avalanches occur when the weak layer of a snowpack is on the top. A sluff is a small slide of dry, powdery snow that moves as a formless mass. Sluffs are much less dangerous than slab avalanches.

A slab avalanche occurs when the weak layer lies lower down in a snowpack. This layer is covered with other layers of compressed snow. When the avalanche is triggered, the weak layer breaks off, pulling all the layers on top of it down the slope. These layers tumble and fall in a giant block, or slab.

Once a slab avalanche starts, the slab shatters into many separate blocks. These snow blocks break up into ever-smaller pieces. Some of the pieces rise into the air as a moving cloud of icy particles. The cloud races downhill at very high speeds.

The thickness and speed of slab avalanches make them a threat to skiers, snowboarders, mountaineers, and hikers. In the mountains of the western United States, there are about 100,000 avalanches each year. Avalanches kill more than 150 people worldwide each year. Most are snowmobilers, skiers, and snowboarders.

Avalanche Control

Storminess, temperature, wind, the steepness of the slope, terrain, vegetation, and general snowpack conditions are all factors that influence whether an avalanche happens and what type occurs.

Snow avalanches are most likely to occur after a fresh snowfall adds a new layer to a snowpack. If new snow piles up during a storm, the snowpack may become overloaded, setting off a slide.

Earthquakes can set off avalanches, but much smaller vibrations can trigger them as well. A single skier can cause enough vibrations to set off a slide. In fact, 90 percent of avalanche incidents involving people are triggered by the victim or someone in the victim's party.

Currently, scientists are not able to predict with certainty when and where avalanches will happen. However, they can estimate hazard levels by checking on the snowpack, temperature, and wind conditions.

Many ski areas employ avalanche control teams to lessen the danger by starting slides before skiers head for the slopes. At some ski areas, patrols use explosives to set off avalanches. Or they may blast hazardous slopes with a cannon to shake loose any large, new accumulations of snow.

In the high mountains of Canada and Switzerland, special military troops are in charge of avalanche control. Many Swiss mountain villages protect homes from snowslides by building large, sturdy structures to anchor snowpacks.

Dangers of an Avalanche

An avalanche is one of the most powerful events in nature. A fractured mass of snow may flow down a slope or become airborne. As a large avalanche speeds down a mountainside, it may compress the air below it, producing a powerful wind that can blow a house apart, breaking windows, splintering doors, and tearing off the roof.

Avalanches strike suddenly and can be deadly. In 1970, a massive avalanche of rocks and ice destroyed the town of Yungay, Peru, killing 18,000 people.

If you are caught in an avalanche, the first thing to do is try to get off the slab. Skiers and snowboarders can head straight downhill to gather speed, and then veer sideways out of the slide path. Snowmobilers can punch the throttle to power out of harm's way. If this is not possible, reach for a tree. As a last resort, try to "swim" up out of the snow. The human body is three times denser than avalanche debris and will sink quickly. This makes finding and rescuing avalanche victims much more difficult.

If buried in an avalanche, try to clear some space in front of you to breathe, then punch a hand skyward. Once the avalanche stops, it settles like concrete. Bodily movement is nearly impossible. Most avalanche victims are rescued, but those who aren't die of suffocation as the snow hardens and buries them.

Avalanche beacons are the most common tools to help rescuers find avalanche victims. Avalanche beacons are "beepers" that emit consistent noise when activated. Beacons can help rescuers locate a buried victim more than 80 meters (262 feet) away.

Fast Fact

Nature's Weapon
During World War I, more than 60,000 Italian and Austrian troops died in avalanches while fighting in snowy mountain passes in the Alps. More than 10,000 died in a single day on December 13, 1916. Avalanches killed more soldiers in World War I than poison gas did.

Fast Fact

Train Wreck
At the end of February 1910, a terrible blizzard struck the town of Wellington, Washington. The nine-day snowfall trapped two trains in the town's depot. On March 1, a thunderstorm unleashed an avalanche, sending a 10-foot wall of snow toward the town. The avalanche hit the train depot and sent the trains sailing 45 meters (150 feet) downhill, killing 96 people.

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During an avalanche, a mass of snow, rock, ice, soil, and other material slides swiftly down a mountainside. Avalanches of rocks or soil are often called landslides. Snowslides, the most common kind of avalanche, can sweep downhill faster than the fastest skier. A snow avalanche begins when an unstable mass of snow breaks away from a slope.

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AVALANCHES ❄️ Natural Disasters in 1 Minute 🏔️

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What Causes an Avalanche? | How To Survive An Avalanche | Natural Disaster | Dr Binocs show

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What is a landslide?A landslide is defined as the movement of a mass of rock, debris, or earth down a slope due to gravity. The materials may move by falling, toppling, sliding, spreading, or flowing.What causes a landslide?Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Landslides can be triggered by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors.What are submarine landslides?Earthquake shaking and other factors can also induce landslides underwater. These landslides are called submarine landslides. Submarine landslides sometimes cause tsunamis that damage coastal areas.Where do landslides occur?Landslides in the United States occur in all 50 States. The primary regions of landslide occurrence and potential are the coastal and mountainous areas of California, Oregon, and Washington, the States comprising the intermountain west, and the mountainous and hilly regions of the Eastern United States. Alaska and Hawaii also experience all types of landslides.How fast do landslide travel?Landslides can move slowly, (millimeters per year) or can move quickly and disastrously, as is the case with debris flows. Debris flows can travel down a hillside at speeds up to 200 miles per hour (more commonly, 30 – 50 miles per hour), depending on the slope angle, water content, volume of debris, and type of earth and debris in the flow. These flows are initiated by heavy periods of rainfall, but sometimes can happen as a result of short bursts of concentrated rainfall or other factors in susceptible areas. Burned areas charred by wildfires are particularly susceptible to debris flows, given certain soil characteristics and slope conditions.Why study landslides?Landslides are a serious geologic hazard. It is estimated that in the United States they cause in excess of $1 billion in damages and from about 25 to 50 deaths each year. Globally, landslides cause billions of dollars in damages and thousands of deaths and injuries each year.Who is most at risk for landslides?As people move into new areas of hilly or mountainous terrain, it is important to understand the nature of their potential exposure to landslide hazards, and how cities, towns, and counties can plan for land-use, engineering of new construction and infrastructure, and other measures which will reduce the costs of living with landslides. Although the physical causes of many landslides cannot be removed, geologic investigations, good engineering practices, and effective enforcement of land-use management regulations can reduce landslide hazards.Do human activities cause landslides?Yes, in some cases human activities can be a contributing factor in causing landslides. Many human-caused landslides can be avoided or mitigated. They are commonly a result of building roads and structures without adequate grading of slopes, of poorly planned alteration of drainage patterns, and of disturbing old landslides.Where can I find landslide information for my area?The USGS National Landslide Information Center (NLIC) is a part of the U.S. Geological Survey Landslide Hazards Program that collects and distributes all forms of information related to landslides. The NLIC is designed to serve landslide researchers, geotechnical practitioners engaged in landslide stabilization, and anyone else concerned in any way with landslide education, hazard, safety, and mitigation. Every state in the US has a geoscience agency and most have some landslide information. The Association of American State Geologists provides links to the State Geologist for every state.

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Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.

Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This is essentially due to a decrease in the shear strength of the slope material, an increase in the shear stress borne by the material, or a combination of the two. A change in the stability of a slope can be caused by a number of factors, acting together or alone. Natural causes of landslides include:

saturation by rain water infiltration, snow melting, or glaciers melting;

rising of groundwater or increase of pore water pressure (e.g. due to aquifer recharge in rainy seasons, or by rain water infiltration);

increase of hydrostatic pressure in cracks and fractures;

loss or absence of vertical vegetative structure, soil nutrients, and soil structure (e.g. after a wildfire - a fire in forests lasting for 3-4 days);

erosion of the top of a slope by rivers or sea waves;

physical and chemical weathering (e.g. by repeated freezing and thawing, heating and cooling, salt leaking in the groundwater or mineral dissolution);

ground shaking caused by earthquakes, which can destabilize the slope directly (e.g., by inducing soil liquefaction) or weaken the material and cause cracks that will eventually produce a landslide;

volcanic eruptions;

Landslides are aggravated by human activities, such as:

temporal variation in land use and land cover (LULC): it includes the human abandonment of farming areas, e.g. due to the economic and social transformations which occurred in Europe after the Second World War. Land degradation and extreme rainfall can increase the frequency of erosion and landslide phenomena.

Hungr-Leroueil-Picarelli classification

In traditional usage, the term landslide has at one time or another been used to cover almost all forms of mass movement of rocks and regolith at the Earth's surface. In 1978, geologist David Varnes noted this imprecise usage and proposed a new, much tighter scheme for the classification of mass movements and subsidence processes. This scheme was later modified by Cruden and Varnes in 1996, and refined by Hutchinson (1988), Hungr et al. (2001), and finally by Hungr, Leroueil and Picarelli (2014). The classification resulting from the latest update is provided below.

Under this classification, six types of movement are recognized. Each type can be seen both in rock and in soil. A fall is a movement of isolated blocks or chunks of soil in free-fall. The term topple refers to blocks coming away by rotation from a vertical face. A slide is the movement of a body of material that generally remains intact while moving over one or several inclined surfaces or thin layers of material (also called shear zones) in which large deformations are concentrated. Slides are also sub-classified by the form of the surface(s) or shear zone(s) on which movement happens. The planes may be broadly parallel to the surface ("planar slides") or spoon-shaped ("rotational slides"). Slides can occur catastrophically, but movement on the surface can also be gradual and progressive. Spreads are a form of subsidence, in which a layer of material cracks, opens up, and expands laterally. Flows are the movement of fluidised material, which can be both dry or rich in water (such as in mud flows). Flows can move imperceptibly for years, or accelerate rapidly and cause disasters. Slope deformations are slow, distributed movements that can affect entire mountain slopes or portions of it. Some landslides are complex in the sense that they feature different movement types in different portions of the moving body, or they evolve from one movement type to another over time. For example, a landslide can initiate as a rock fall or topple and then, as the blocks disintegrate upon the impact, transform into a debris slide or flow. An avalanching effect can also be present, in which the moving mass entrains additional material along its path.

Slope material that becomes saturated with water may produce a debris flow or mud flow. However, also dry debris can exhibit flow-like movement. Flowing debris or mud may pick up trees, houses and cars, and block bridges and rivers causing flooding along its path. This phenomenon is particularly hazardous in alpine areas, where narrow gorges and steep valleys are conducive of faster flows. Debris and mud flows may initiate on the slopes or result from the fluidization of landslide material as it gains speed or incorporates further debris and water along its path. River blockages as the flow reaches a main stream can generate temporary dams. As the impoundments fail, a domino effect may be created, with a remarkable growth in the volume of the flowing mass, and in its destructive power.

An earthflow is the downslope movement of mostly fine-grained material. Earthflows can move at speeds within a very wide range, from as low as 1 mm/yr to many km/h. Though these are a lot like mudflows, overall they are more slow-moving and are covered with solid material carried along by the flow from within. Clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. These flows are usually controlled by the pore water pressures within the mass, which should be high enough to produce a low shearing resistance. On the slopes, some earthflow may be recognized by their elongated shape, with one or more lobes at their toes. As these lobes spread out, drainage of the mass increases and the margins dry out, lowering the overall velocity of the flow. This process also causes the flow to thicken. Earthflows occur more often during periods of high precipitation, which saturates the ground and builds up water pressures. However, earthflows that keep advancing also during dry seasons are not uncommon. Fissures may develop during the movement of clayey materials, which facilitate the intrusion of water into the moving mass and produce faster responses to precipitation.

A rock avalanche, sometimes referred to as sturzstrom, is a large and fast-moving landslide of the flow type. It is rarer than other types of landslides but it is often very destructive. It exhibits typically a long runout, flowing very far over a low-angle, flat, or even slightly uphill terrain. The mechanisms favoring the long runout can be different, but they typically result in the weakening of the sliding mass as the speed increases. The causes of this weakening are not completely understood. Especially for the largest landslides, it may involve the very quick heating of the shear zone due to friction, which may even cause the water that is present to vaporize and build up a large pressure, producing a sort of hovercraft effect. In some cases, the very high temperature may even cause some of the minerals to melt. During the movement, the rock in the shear zone may also be finely ground, producing a nanometer-size mineral powder that may act as a lubricant, reducing the resistance to motion and promoting larger speeds and longer runouts. The weakening mechanisms in large rock avalanches are similar to those occurring in seismic faults.

Slides can occur in any rock or soil material and are characterized by the movement of a mass over a planar or curvilinear surface or shear zone.

A debris slide is a type of slide characterized by the chaotic movement of material mixed with water and/or ice. It is usually triggered by the saturation of thickly vegetated slopes which results in an incoherent mixture of broken timber, smaller vegetation and other debris. Debris flows and avalanches differ from debris slides because their movement is fluid-like and generally much more rapid. This is usually a result of lower shear resistances and steeper slopes. Debris slides generally begin with the detachment of rock chunks high on the slopes, which break apart as they slide towards the bottom.

Clay and silt slides are usually slow but can experience episodic acceleration in response to heavy rainfall or rapid snowmelt. They are often seen on gentle slopes and move over planar surfaces, such as over the underlying bedrock. Failure surfaces can also form within the clay or silt layer itself, and they usually have concave shapes, resulting in rotational slides

Shallow and deep-seated landslides

A landslide in which the sliding surface is located within the soil mantle or weathered bedrock (typically to a depth from few decimeters to some meters) is called a shallow landslide. Debris slides and debris flows are usually shallow. Shallow landslides can often happen in areas that have slopes with high permeable soils on top of low permeable soils. The low permeable soil traps the water in the shallower soil generating high water pressures. As the top soil is filled with water, it can become unstable and slide downslope.

Deep-seated landslides are those in which the sliding surface is mostly deeply located, for instance well below the maximum rooting depth of trees. They usually involve deep regolith, weathered rock, and/or bedrock and include large slope failures associated with translational, rotational, or complex movements. They tend to form along a plane of weakness such as a fault or bedding plane. They can be visually identified by concave scarps at the top and steep areas at the toe.

Causing tsunamis

Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate tsunamis. Massive landslides can also generate megatsunamis, which are usually hundreds of meters high. In 1958, one such tsunami occurred in Lituya Bay in Alaska.

Related phenomena

An avalanche, similar in mechanism to a landslide, involves a large amount of ice, snow and rock falling quickly down the side of a mountain.

A pyroclastic flow is caused by a collapsing cloud of hot ash, gas and rocks from a volcanic explosion that moves rapidly down an erupting volcano.

Landslide prediction mapping

Landslide hazard analysis and mapping can provide useful information for catastrophic loss reduction, and assist in the development of guidelines for sustainable land-use planning. The analysis is used to identify the factors that are related to landslides, estimate the relative contribution of factors causing slope failures, establish a relation between the factors and landslides, and to predict the landslide hazard in the future based on such a relationship. The factors that have been used for landslide hazard analysis can usually be grouped into geomorphology, geology, land use/land cover, and hydrogeology. Since many factors are considered for landslide hazard mapping, GIS is an appropriate tool because it has functions of collection, storage, manipulation, display, and analysis of large amounts of spatially referenced data which can be handled fast and effectively. Cardenas reported evidence on the exhaustive use of GIS in conjunction of uncertainty modelling tools for landslide mapping. Remote sensing techniques are also highly employed for landslide hazard assessment and analysis. Before and after aerial photographs and satellite imagery are used to gather landslide characteristics, like distribution and classification, and factors like slope, lithology, and land use/land cover to be used to help predict future events. Before and after imagery also helps to reveal how the landscape changed after an event, what may have triggered the landslide, and shows the process of regeneration and recovery.

Using satellite imagery in combination with GIS and on-the-ground studies, it is possible to generate maps of likely occurrences of future landslides. Such maps should show the locations of previous events as well as clearly indicate the probable locations of future events. In general, to predict landslides, one must assume that their occurrence is determined by certain geologic factors, and that future landslides will occur under the same conditions as past events. Therefore, it is necessary to establish a relationship between the geomorphologic conditions in which the past events took place and the expected future conditions.

Natural disasters are a dramatic example of people living in conflict with the environment. Early predictions and warnings are essential for the reduction of property damage and loss of life. Because landslides occur frequently and can represent some of the most destructive forces on earth, it is imperative to have a good understanding as to what causes them and how people can either help prevent them from occurring or simply avoid them when they do occur. Sustainable land management and development is also an essential key to reducing the negative impacts felt by landslides.

GIS offers a superior method for landslide analysis because it allows one to capture, store, manipulate, analyze, and display large amounts of data quickly and effectively. Because so many variables are involved, it is important to be able to overlay the many layers of data to develop a full and accurate portrayal of what is taking place on the Earth's surface. Researchers need to know which variables are the most important factors that trigger landslides in any given location. Using GIS, extremely detailed maps can be generated to show past events and likely future events which have the potential to save lives, property, and money.

Since the '90s, GIS have been also successfully used in conjunction to decision support systems, to show on a map real-time risk evaluations based on monitoring data gathered in the area of the Val Pola disaster (Italy).

Trackside rock slide detector on the UPRR Sierra grade near Colfax, CA

Prehistoric landslides

Storegga Slide, some 8,000 years ago off the western coast of Norway. Caused massive tsunamis in Doggerland and other countries connected to the North Sea. A total volume of 3,500 km³ (840 cu mi) debris was involved; comparable to a 34 m (112 ft) thick area the size of Iceland. The landslide is thought to be among the largest in history.

Landslide which moved Heart Mountain to its current location, the largest continental landslide discovered so far. In the 48 million years since the slide occurred, erosion has removed most of the portion of the slide.

Flims Rockslide, ca. 12 km³ (2.9 cu mi), Switzerland, some 10000 years ago in post-glacial Pleistocene/Holocene, the largest so far described in the alps and on dry land that can be easily identified in a modestly eroded state.

The landslide around 200 BC which formed Lake Waikaremoana on the North Island of New Zealand, where a large block of the Ngamoko Range slid and dammed a gorge of Waikaretaheke River, forming a natural reservoir up to 256 metres (840 ft) deep.

Cheekye Fan, British Columbia, Canada, ca. 25 km² (9.7 sq mi), Late Pleistocene in age.

The Manang-Braga rock avalanche/debris flow may have formed Marsyangdi Valley in the Annapurna Region, Nepal, during an interstadial period belonging to the last glacial period. Over 15 km³ of material are estimated to have been moved in the single event, making it one of the largest continental landslides.

A massive slope failure 60 km north of Kathmandu Nepal, involving an estimated 10-15 km³. Prior to this landslide the mountain may have been the world's 15th mountain above 8000m.

Historical landslides

Main page: List of landslides

The 1806 Goldau landslide on September 2, 1806

The Cap Diamant Québec rockslide on September 19, 1889

Frank Slide, Turtle Mountain, Alberta, Canada, on 29 April 1903

Khait landslide, Khait, Tajikistan, Soviet Union, on July 10, 1949

A Magnitude 7.5 earthquake in Yellowstone Park (August 17, 1959) caused a landslide that blocked the Madison River, and created Quake Lake.

Monte Toc landslide (260 million cubic metres, 9.2 billion cubic feet) falling into the Vajont Dam basin in Italy, causing a megatsunami and about 2000 deaths, on October 9, 1963

Hope Slide landslide (46 million cubic metres, 1.6 billion cubic feet) near Hope, British Columbia on January 9, 1965.

The 1966 Aberfan disaster

Tuve landslide in Gothenburg, Sweden on November 30, 1977.

The 1979 Abbotsford landslip, Dunedin, New Zealand on August 8, 1979.

The eruption of Mount St. Helens (May 18, 1980) caused an enormous landslide when the top 1300 feet of the volcano suddenly gave way.

Val Pola landslide during Valtellina disaster (1987) Italy

Thredbo landslide, Australia on 30 July 1997, destroyed hostel.

Vargas mudslides, due to heavy rains in Vargas State, Venezuela, in December, 1999, causing tens of thousands of deaths.

2005 La Conchita landslide in Ventura, California causing 10 deaths.

2007 Chittagong mudslide, in Chittagong, Bangladesh, on June 11, 2007.

2008 Cairo landslide on September 6, 2008.

disaster caused 37 deaths, on October 1.

The 2010 Uganda landslide caused over 100 deaths following heavy rain in Bududa region.

Zhouqu county mudslide in Gansu, China on August 8, 2010.

Devil's Slide, an ongoing landslide in San Mateo County, California

2011 Rio de Janeiro landslide in Rio de Janeiro, Brazil on January 11, 2011, causing 610 deaths.

2014 Pune landslide, in Pune, India.

2014 Oso mudslide, in Oso, Washington

2017 Mocoa landslide, in Mocoa, Colombia

Extraterrestrial landslides

Evidence of past landslides has been detected on many bodies in the solar system, but since most observations are made by probes that only observe for a limited time and most bodies in the solar system appear to be geologically inactive not many landslides are known to have happened in recent times. Both Venus and Mars have been subject to long-term mapping by orbiting satellites, and examples of landslides have been observed on both planets.

In Spanish: Corrimiento de tierra para niños

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Volcano | The Dr. Binocs Show | Learn Videos For Kids

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Volcano facts | National Geographic Kids

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Check out these fascinating volcano facts with National Geographic Kids! What is a volcano? Why does it erupt? And where can you find the world's biggest?

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Volcano | Volcanic Eruption | Teaching Wiki - Twinkl

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Find out how volcanoes are formed, which country has the most volcanoes in the world & more. With fun volcano facts for kids plus general info & resources.

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A powerful eruption of Guatemala's Fuego volcano in June 2018 buried villages in ash and lava. The volcano reportedly blasted a river of red, hot lava and ejected thick clouds of smoke nearly six miles into the air. A second, unprecedented eruption a few days later sparked fresh panic among affected communities, endangering even more lives and halting rescue efforts.

Over 1.7 million people are estimated to have been affected and sadly over 100 people lost their lives. Towns were wiped off the map, buried in ash and lava.

Our response team distributed household kits, that contains essential items like; blankets, tarpaulin, rope, a jerry can and soap. We also set up and managed Child Friendly Spaces to help protect children caught up in the emergency.

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Volcanic Eruption | Save the Children UK

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A powerful eruption of Guatemala's Fuego volcano in June 2018 buried villages in ash and lava. The volcano reportedly blasted a river of red, hot lava and ejected thick clouds of smoke nearly six miles into the air. A second, unprecedented eruption a few days later sparked fresh panic among affected communities, endangering even more lives and halting rescue efforts.

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A volcano is an opening in the Earth's crust that allows molten rock, gases and debris to escape to the surface. During a volcanic eruption, lava and other debris can flow at speeds of up to 100 mph, destroying everything in their path. Volcanic ash can travel hundreds of miles and cause severe health problems.

A volcanic eruption can:

Contaminate water supplies.

Damage machinery.

Reduce visibility through smog and harmful gases that may threaten low-lying areas.

Make it hard to breathe and irritate the skin, eyes, nose and throat.

IF YOU ARE UNDER A VOLCANO WARNING:

Listen for emergency information and alerts.

Follow evacuation or shelter orders. If advised to evacuate, do so early.

Reduce your ash exposure by doing the following:

Limit your time outdoors and use a dust mask or cloth mask as a last resort if you must be outside.

Avoid areas downwind and river valleys downstream of the volcano.

Take temporary shelter from volcanic ash in the location where you are.

Cover ventilation openings and seal doors and windows.

Avoid driving in heavy ash. If you must drive, keep the windows up and do not use the air conditioning system.

Do not get on your roof to remove ash.

Stay indoors until authorities say it is safe to go outside.

Prepare NOW

Survive DURING

Be Safe AFTER

Related Content

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Learn what to do if you are under a volcano warning and how to stay safe when a volcano threatens. Prepare Now Survive During Be Safe After Related Content A volcano is an opening in the Earth's crust that allows molten rock, gases and debris to escape to the surface.

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What is hail? How is hail formed and why does it happen? | Weather Wise

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A piece of hail (called a hailstone) is a lump of ice that falls out of a storm cloud. About 5,000 hailstorms a year in the United States of America make hail 3/4 of an inch or bigger.

The beginning of a hailstorm

A hailstone begins as a small water drop or a round snow pellet in a cloud. The drop grows by collecting many cloud drops. The little drop is blown by a strong wind inside the cloud to where it meets with some extremely cold water drops. These supercooled drops are still liquid water even though the temperature is below freezing. When the little drop mixes with these extremely cold drops, they join, and the little drop has now become a hailstone.

The little hailstone is thrown up inside the cloud, still collecting other cold drops. The hailstone gets bigger and bigger until it goes to the top of the cloud. Then, because there is no more wind, it falls back down through the cloud. While it is falling it gets even bigger as it bangs into more supercooled drops. If it goes down very fast it can hit the earth at up to 90 mph (144 kph), bouncing like popcorn. If the hailstone hits dirt, it can actually bury itself.

Hailstone sizes

The biggest hailstone recorded in the United States weighed 1.67 pounds (0.75 kg), and was 5.5 inches (14 cm) across. It fell near Coffeyville, Kansas, on September 3, 1970. The biggest recorded hailstone in the world was 4.2 pounds (almost 2 kilograms). It fell in Kazakhstan in Asia.

Hailstones are made of many rings of clear, cloudy ice. The rings show different amounts of freezing on the hailstone. The cloudy ice is because it freezes so quickly, trapping many small air bubbles. The clear rings are made by slow freezing of the water, which lets bubbles escape.

Hail damage and protection

Hail does a very great amount of damage every year. Even small hail with strong winds can crush a field of wheat flat in a few minutes. It sometimes breaks windows, and can dent cars and roofs. Big hailstones can hurt and even kill small animals.

Because hail damages crops, there has been many efforts to stop hail. In the 16th century, farmers used to shoot cannons at thunderstorms, thinking this would destroy the hail. Cloud seeding (trying to make rain by putting dry ice crystals or a kind of smoke in clouds) is the more recent way, but it is expensive and we do not know for sure how well it works. To this day, there is no proved way of stopping hailstorms.

Images for kids

In Spanish: Granizo para niños

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It's not just raindrops that fall during thunderstorms. Sometimes ice falls too. The ice is called hail, and it can form even during the warmth of summer. High up in a storm cloud, it's so cold that small pieces of ice can form. The winds within the storm cloud can cause the ice to swirl around. When it bumps into cold water droplets, the water freezes onto the ice, making hail grow larger. Eventually, the hail is so big and heavy that it falls to the ground.

Hail can be the size of peas. Large hail can be the size of a grapefruit and destructive. It's heavy enough to dent cars and break windshields when it falls.

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It's not just raindrops that fall during thunderstorms. Sometimes ice falls too. The ice is called hail, and it can form even during the warmth of summer. High up in a storm cloud, it's so cold that small pieces of ice can form. The winds within the storm cloud can cause the ice to swirl around.

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Toss supercooled water into an updraft of air within a thundercloud and what do you get? A hailstorm!

Subjects

Earth Science, Meteorology

Image

Hail Damage to Minivan Windshield

Hail is supercooled water, which is refrozen in the atmosphere, before falling back to the ground as a sizable ice ball. Hail can cause severe damage to life and property, like this minivan windshield.

Photography by mwesselsphotography

Imagine balls of ice, some small, some the size of grapefruits, crashing to the ground in a storm. Sound like a nightmare? For people who experience these storms, it can be. Those balls of ice are hailstones, and they can damage cars, airplanes, and crops, and in some circumstances can even kill animals and people.

Hail forms from supercooled water. Supercooled water is something unique-it's water that is below its normal freezing point of 0°C (32°F) and yet remains a liquid. Scientists aren't exactly sure how this happens, but they do know that it occurs frequently in the upper atmosphere. Supercooled water will freeze when it comes in contact with something, like an ice crystal, dust particle, or raindrop. Hail is associated with high, vertical cumulonimbus clouds, the kind of clouds that produce severe thunderstorms.

Within a cumulonimbus cloud, ice particles develop from supercooled water. The particles fall toward the bottom of the cloud from the pull of gravity, but they are forced back up by powerful updrafts of air within the clouds. In the upper part of the cloud, they encounter more supercooled water, which freezes on the ice particles, adding another layer of ice to them. This happens repeatedly. In this way, the small bits of ice grow larger and larger, becoming balls of ice-hailstones. The hailstones finally become too heavy to be lofted back up to the top of the cloud and they fall to the earth.

Because of the way they form, hailstones have a layered structure, like an onion. Really large hailstones form in storm clouds with exceptionally strong updrafts.

The National Weather Service in the United States defines large hail as being at least 2.5 centimeters (one inch) in diameter. That's about the width of a quarter. This size distinction is important because hailstones this size or larger can cause damage to property, crops, and structures. It is difficult to determine the speed hailstones fall from clouds. But one estimate, from the National Severe Storms Laboratory, is that a hailstone the size of a baseball will fall at about 161 kilometers (100 miles) per hour.

Hail does significant damage to homes and crops worldwide. One of the most devastating hailstorms in U.S. history hit near Phoenix, Arizona, in October 2010. Hailstones as big as 7.6 centimeters (three inches) were reported and $2.8 billion in damage was done. The largest hailstone ever recovered in the United States was produced by a storm in the U.S. state of South Dakota in June 2010. It was 20 centimeters (8 inches) in diameter and weighed about 0.9 kilograms (two pounds).

Media Credits

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Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society

Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society, National Geographic Society

Margot Willis, National Geographic Society

other

Last Updated

October 19, 2023

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Toss supercooled water into an updraft of air within a thundercloud and what do you get? A hailstorm!

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What is Hail?

Hail is a type of precipitation that gets caught in strong winds that are moving up. When it starts to fall, more water droplets attach to the balls of ice. Then, more strong winds push the chunks of ice up again and the tiny ice crystals form another layer. Hail can be perfectly round or uneven in shape.

How Does Hail Form?

The formation of hailstones happens when drops of water freeze in the top part of the cloud. Strong updrafts take the ice balls up to cold areas of the upper atmosphere and more water vapor turns into ice pellets. Big hailstones form as they get caught in wind gusts over and over again adding another layer of ice each time. The stronger the updrafts are then the bigger the hail will be.

Sometimes in freezing air, water droplets will combine with the hailstone and freeze instantly. When this happens, the hail is cloudy because it has air bubbles in it. If the freezing happens slowly, then the hailstones will actually be clear. The next time you see hail pay attention to if it is clear ice or cloudy ice and then you will know why.

Hail in Warm Weather

Hail happens in the Fall, Spring, and Summer seasons. You wouldn't think ice would fall from the sky in warm weather, but it does. Even if the air temperature is warm, if the upper atmosphere is still cold then hail can form. If thunderstorm updrafts push the water vapor up into the cumulonimbus clouds (storm clouds) then it will freeze and create a hail storm. Hail is actually most common in the months of May, June, July, and August.

If you were looking down from the sky, you would be able to see the path of a hailstorm. The path of a hailstorm is called hail swaths. There are even HailSWATH maps that you can look at for information about where different sized hail has fallen and the most common days of hail.

Where Does it Hail the Most?

Smaller hailstones can happen during thunderstorms with gusty winds and heavy rain anywhere. However, large hailstones aren't as common. Although hail can happen anywhere, there are certain parts of the world that have a better chance of seeing hail every year.

Colorado, Nebraska, and Wyoming are three states that people have nicknamed Hail Alley. These states can see hail several times (6-10) each year. That's a lot!

In fact, Cheyenne, Wyoming is known as the hail capital of the United States because it hails there so often. Other countries like Northern Italy, China, Russia, and India also see hailstorms. The city of Kericho in Kenya holds the record for the most days with hail (132 days in one year).

Damaging Hailstorms

Depending on the size of the hail or wind speeds during a hailstorm, a lot of damage can happen. This is called hail damage. During heavy hailstorms, extreme damage can occur. Power lines can go down causing the power to turn off at your house. Larger hails can fall and reach speeds of up to 100 miles per hour. Hail could break windows or dent cars and roofs.

Size of Hail

The size of hail can be small like the size of a jelly bean, medium sized like a golf ball, or even large like the size of baseballs. Hailstones measuring .2 inches to 6 inches are the average size. The largest hailstone ever recorded was 8 inches. The heaviest weight of a hailstone to be recorded is about 2 pounds.

Warning Signs of Hail

Predicting hail is very difficult for scientists. Days that have warmer temperatures (warm air) and mid to high humidity (moist air) can create hail.

In the United States, the National Weather Service keeps an eye on the weather and can issue a severe thunderstorm warning which will help people prepare for severe thunderstorms and the possibility of hail. They call it severe hail if it is larger than 1 inch.

Fun Facts about Hail

The bigger the hailstone is, the higher in the sky it fell from.

Hail usually starts very suddenly and only lasts a couple of minutes.

If you cut a hailstone in half you will see different rings. The number of rings will tell you how many times it traveled to the top of the storm cloud. This is similar to how tree trunk have rings to show how many years they have lived.

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Hail is a type of precipitation that gets caught in strong winds that are moving up. When it starts to fall, more water droplets attach to the balls of ice. Then, more strong winds push the chunks of ice up again and the tiny ice crystals form another layer.

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Hail is precipitation in the form of a chunk of ice that can fall from a cumulonimbus cloud. Usually associated with multicell, supercell and cold front-induced squall line thunderstorms, most hail falls from the central region of a cloud in a severe storm. If you are caught in a hailstorm:

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Hail is in the forecast-are you ready? Is your home or car vulnerable to damage? While hailstorms are usually short-lived, they can develop quickly and be very destructive. Learn what to do before, during and after a hailstorm so you can be prepared.

Some facts about hailstorms in Canada

Peak hail season in Canada is from May to October. July is the most active month for hail.

Hailstones can be as small as pebbles and as big as baseballs-but even the smallest hailstones can cause serious damage in just minutes.

Hail can fall at up to 100 km/h.

The Prairies can see as many as 10 hailstorms a year.

Hailstorms are most frequent in Alberta, followed by Ontario.

To learn more about hailstorms, visit Environment and Climate Change Canada

Know when a storm is coming

Check your local weather forecast or Environment Canada for hail warnings.

Also check for thunderstorm warnings because they may include hail.

Download The Personal mobile app to get , our severe weather alert service. It sends an alert to your smartphone if hail or other severe weather is headed your way.

Protect yourself and your family during a storm

If you're outdoors

Take shelter in a solid building and stay away from windows, glass doors and skylights.

If there is nowhere to take shelter, crouch down and protect your head and neck with your arms.

Hailstorms can be accompanied by lightning, so stay away from tall objects such as large trees, towers, metal fences or poles.

If you're indoors

Close and lock windows and doors.

Close curtains and blinds to help protect you if the windows break.

If there's a power outage, unplug electronics and appliances to avoid damage from a power surge.

If possible, use a flashlight instead of candles, which can be a fire hazard.

If you're driving

Find a place to safely pull over. Protect yourself in case the car windows shatter.

Watch out for flooded areas. Hail and heavy rain together can block storm drains and cause flash flooding.

Protect your property during a storm

Put vehicles in the garage or cover them with a thick blanket.

Cover or store outdoor items and furniture.

Make your home more resistant

If you live in an area where hail is common, you can take steps to make your home more resistant to hail damage.

Keep your eavestroughs clear of debris to reduce the risk of ice dams and water damage.

Keep trees and shrubs trimmed and remove tree branches that could fall on your home.

Repair any damaged areas on your roof. If you're thinking of getting a new roof, consider impact-resistant asphalt shingles.

Consider installing impact-resistant storm shutters to cover windows, skylights and sliding doors.

Check your insurance for hail damage cover

Before the next hailstorm hits, check with your insurance company to make sure any damage to your home or property is covered. Damage to vehicles from hail is usually covered if you have purchased Comprehensive car insurance.

After the storm

Take a walk around your property and take note of any damage to your home or car. To help with the insurance claim process, take photos of the damage and make an inventory of damaged items. Also keep receipts if you spent money on clean-up.

Let your insurance company know if your home or car was damaged in a hailstorm so they can walk you through the claims process.

For more on this topic, visit:
Preparing for a natural disaster How to prevent damage to your property Family safety plan Ice storms and hailstorms Protect your home from hail: pdf booklet from the Institute for Catastrophic Loss Reduction

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How to Prepare for a Hailstorm | The Personal

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Hail is in the forecast-are you ready? Is your home or car vulnerable to damage? While hailstorms are usually short-lived, they can develop quickly and be very destructive. Learn what to do before, during and after a hailstorm so you can be prepared..

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Video: What is a Tornado? The Dr. Binocs Show 

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Video: What is a Tornado? The Dr. Binocs Show 

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What is a Tornado? The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz

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What is a Tornado? | Weather Science | SciShow Kids

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Drought - The Dr. Binocs Show | Best Learning Videos For Kids | Peekaboo Kidz

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What Causes Droughts? | What Is A Drought? | Science Facts | Science Facts For Kids | Biology Facts

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Worst drought in 30 years hits Sout Africa  - BBC News

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Drought is a continuous period of dry weather when an area gets less than its normal amount of rain. Droughts can last months or even years. Because crops and other plants need water to grow and land animals need water to live, droughts can be dangerous. Because of the lack of water, famine occurs and sometimes deserts are created. Many people die every year in famines that are due to drought in subsistence farming areas. Sometimes conflicts can occur because of drought.

A drought is a natural event that is caused by other weather events like El Niño, high-pressure systems, and global warming. Drought can be triggered by people as well. Deforestation (people cutting down trees in forests and not replanting more trees), diverting (redirecting) rivers, and emptying lakes are ways that man interferes with nature and can cause drought.

It is often difficult to determine a specific time when a drought started because drought is a disaster that usually takes place slowly. Its effects often build up slowly over a long time and may last from months to years, even after rain resumes.

Causes of drought

Lack of Rain (precipitation)

Water can fall in three ways from the sky:

1. Water that falls as a liquid and stays a liquid,

2. Water that falls as a liquid and freezes when it touches the ground, and

3. Water that is already frozen and falls as ice.

Droughts occur mainly in areas where the normal levels of rainfall are already low. If it rains a little less than normal over time, a drought will happen. Wind can also be one of the factors in a drought when there is already a lack of rain. If a dry wind blows (like a wind from over the land) rather than a more humid wind (like a wind from over the ocean), it can dry the land faster.

In the tropics (the areas of the earth that are closest to the equator), there are distinct wet and dry seasons. During the wet seasons, the area becomes a Monsoon trough because monsoons are pulled into the movement of air. During the dry seasons, the Intertropical Convergence Zone ( Monsoon trough) moves dry air through the tropics. The movement of dry air eventually causes watering holes and rivers to dry up. This means that many grazing animals like zebras, elephants, and wildebeest are faced with a choice: move (migrate) to where there is water or die. The fruit and vegetable-bearing plants that are left ripen faster because evaporation and transpiration from the plants are increased. Bushfires are common during the dry season as well because of the lack of water in the remaining plants.

El Niño is a natural event that takes place when seawater temperature rises in the tropical Pacific Ocean. This changes the atmospheric pressure between the Pacific and Indian Oceans. Since atmospheric pressure determines weather, during El Niño we see drought in some areas of the world and heavy rainfall in other areas.

Erosion and human activities

Erosion is a process in which natural forces like wind, air, water, and gravity cause the earth to move or wear away. In dry, or arid, climates, the main source of erosion is the wind. Because the soil is already dry, wind can lift small particles and move them to another region. Particles that are suspended in the wind may rub against solid objects and cause erosion by abrasion. Wind erosion usually happens in areas where there is not enough rainfall to grow many plants.

Loess is a type of soil that is affected by wind erosion. It looks like little cliffs of sand and is common in the middle of the United States and other areas of the world like China, Hungary, and Belgium. Windbreaks (like large trees and bushes) are planted on and near loess to help block as much wind as possible.

Climate change

Scientists expect that because of global climate change, droughts will be triggered. Overall, they state that global warming will result in more rain falling all over the world, but areas that are prone to drought will increase as well. Some of the suggestions to fight global warming, however, involve the use of a space sunshade, which may also increase the chances of drought.

Types of drought

As drought continues, the conditions surrounding it gradually worsen and those living in drought areas are more affected. People define droughts in three main ways:

1. Meteorological drought happens when there is a prolonged time that an area receives less than its average precipitation. Meteorological drought usually comes before other kinds of drought.

2. Agricultural drought affects crop production or the ecology of a distinct area. This can happen because of poorly planned farming areas. The water that is available in the area has a hard time reaching the plants or erosion occurs. Meteorological drought conditions can affect agriculture as well.

3. Hydrological drought happens when the water in reserves like aquifers, lakes, and reservoirs drops below their normal amount. We see the effects of hydrological drought more slowly because it involves stored water that is used or moved but not refilled. This can be caused by people using or moving water or by a lack of rainfall.

Consequences of drought

The consequences of droughts and water shortages can be divided into three groups:

1. Environmental: Water levels drop and there is a lower flow of water. This lack of water is dangerous for animals that live in water. We see more pollution on the surface of the water. Wetlands dry out, causing more and larger fires. Wind erosion happens more easily, and plant life has a hard time surviving because of a lack of water, pests, and diseases. Animals have to move because of the lack of water and plants.

2. Economic: Farming is less successful during a drought, which means the price of groceries is affected because there is less food to sell. Livestock is more difficult to care for during a drought. Forests have fewer healthy trees and fewer animals. Energy production decreases in hydro plants (businesses that use water to make energy). Tourism even decreases because activities that involve water have a harder time working correctly.

3. Social: People's health can be affected by heat waves and having to use less water. People can become stressed due to higher food costs and the lack of other things that are normal in their life. Drought also results in snakes moving closer to water and food in residential areas resulting in more snake bites. Less-developed countries have more difficulties with water shortages because they do not have the same helpful equipment as more-developed countries. Sometimes they have to move because of pollution or lack of water. War can even break out because people or countries could begin fighting over food and water.

History of drought

Drought is a normal part of the cycle of the climate in most parts of the world. It is written about in the Epic of Gilgamesh and the Biblical story of Joseph. Historians believe that people migrated out of Chile and Africa thousands of years ago because of drought.

Well-known historical droughts include:

1900: a drought in India that killed between 250,000 and 3.25 million.

1921-22: drought in the Soviet Union in which over 5 million died from starvation

1928-30: a drought in Northwest China resulted in over 3 million deaths by famine.

1936 and 1941: droughts Sichuan Province China resulted in 5 million and 2.5 million deaths respectively.

The 1997-2009 Millennium Drought in Australia led to a water supply crisis across much of the country. As a result, many desalination plants were built for the first time.

In 2006, Sichuan Province, China, experienced its worst drought in modern times with nearly 8 million people and over 7 million cattle facing water shortages.

A 12-year drought that was devastating southwest Western Australia, southeast South Australia, Victoria, and northern Tasmania was "very severe and without historical precedent".

In 2005, the Amazon basin experienced its worst drought in 100 years.

Recurring droughts in East Africa have caused desert areas to grow. This is called desertification.

In 2012, a severe drought struck the western Sahel. 10 million people were at risk of famine and almost $1 billion was sent to help.

Protection, mitigation, and relief

Farmers can lessen the effects of (mitigate) drought by properly watering and rotating their crops. Agencies have been formed to focus on soil preservation. This began in 1935 after President Roosevelt signed documents creating the Soil Conservation Service. The name has since been changed to the Natural Resources Conservation Service.

Here is a list of ways that we can protect against drought, lessen the effects of drought, and bring relief to those who are affected by drought:

Cloud seeding: This is a form of purposely changing the weather to bring rainfall. This remains a hotly debated topic and there is not yet scientific proof that it would work.

Dams: Many dams and their associated reservoirs supply additional water in times of drought.

Desalination: Removing salt from seawater could make more fresh water available for watering plants and drinking.

Drought Monitoring: If we can closely watch and measure rainfall levels and compare them with current water usage, it could help prevent man-made drought.

Land use: Carefully planned crop rotation can help to minimize erosion and allow farmers to plant less water-dependent crops in drier years.

Outdoor water-use restriction: Regulating the use of sprinklers, hoses, or buckets for outdoor home maintenance can help prevent drought. In drier climates, it is popular to Xeriscape yards. Planning the landscaping in a way that requires little or no watering is a good way to preserve water.

Rainwater harvesting: We can collect and store water that is already given to us naturally. Rainwater from roofs or other surfaces can be used when we would normally use a hose.

Recycled water: Former wastewater (sewage) that has been treated and purified can be reused.

Transvasement: We can build canals or redirect rivers toward drought-prone areas.

Interesting facts about drought

Drought is a time when the land is too dry.

Drought can be caused by nature or by man.

When areas do not get enough rain, drought happens.

Weather patterns can bring about drought.

Erosion of soil can cause drought.

Humans can bring about drought by deforestation or using too much water.

Drought can have serious consequences: It can be bad for the environment and living things in certain areas, it can cause changes in the economy of an area or country, and it can affect the health of people.

There are many ways that people can help prevent drought and help areas that are naturally prone to drought.

Images for kids

Global drought total economic loss risk

Pair of dead oryx in Namibia during the 2018-19 Southern Africa drought.

In Spanish: Sequía para niños

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What is a drought and what are the causes?

Droughts occur when prolonged periods of drier-than-average weather lead to shortages in water supplies The extent of droughts can vary by region, and long periods of drought can have widespread effects on the lives of children and families around the world.

Common Effects of Droughts

A drought can carry various implications depending on its geography. Some effects of drought include:

Agricultural impacts, such as withering crops and dying livestock

Mass migration away from the drought-affected areas

Increasing rates of malnutrition due to insufficient food

Education disruption in school-age children

How Climate Change Impacts Droughts

The climate crisis is a major driver of extreme weather conditions including drought. Excess heat associated with climate change will increase dry climates' susceptibility to drought conditions and the severity of their effects.

Droughts Affect Children Around the World

Droughts threaten the lives of millions of children around with world. Today, almost 160 million children are exposed to severe and prolonged droughts. By 2040, it is estimated that one in four children will be living in areas with extreme water shortages.

In Africa, Droughts Pose a High Risk

There are many regions in Africa that are particularly susceptible to droughts.

The Horn of Africa, for example, has experience too little rain or no rain at all for the last 7 out of 8 rainy seasons.

Save the Children has been working in many African countries affected by droughts, including Somalia, Ethiopia and Kenya in the Horn of Africa. We have implemented resilience programs to address the long-term impacts of climate change.

In Somalia, we are supporting the establishment and training of community-based disaster management committees that can develop their own plans and strategies to adapt to disasters according to their local needs and contexts.

In Ethiopia, we are supporting unemployed young 'pastoralist drop-outs' who were forced by the circumstances to give up the cattle farmer trade. Our programs work to get them training that suits their interests and skills, and that will give them sustainable incomes in the future.

In Kenya, we are supporting women-led loans and savings groups, so families can start small-scale businesses, run sustainable kitchen gardens, and raise livestock appropriate for drought conditions.

Droughts in the United States

Droughts can occur in any region of the world, including the U.S. Today, droughts in the U.S. are concentrated in the west part of the country. States like California, Nevada, Utah and Arizona are experiencing unprecedented heat and dry weather.
*Name changed for protection

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Droughts: Facts, Causes, and How We Can Help

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Droughts occur when prolonged periods of drier-than-average weather lead to shortages in water supplies The extent of droughts can vary by region, and long periods of drought can have widespread effects on the lives of children and families around the world. A drought can carry various implications depending on its geography.

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Rainy days can be a bit of a bummer. For many, a rainy day means being pent up inside and missing out on all kinds of fun outdoor activities. Cancelled baseball games. No afterschool soccer. Who needs that?

The state of California does, actually. California is in the middle of its third year of intense drought. If you are an outdoor enthusiast who dislikes rain, California is probably the place for you! You can count the number of significant rainstorms California has experienced over the last year on one hand. The past two winters have been among the driest since record keeping began in 1879.

Problems for California Farmers

Don't pack your bags just yet. Despite it putting a crimp in your outdoor fun, rain is actually vitally important. Not only do the millions of people in California need water to drink, California farmers also need to figure out how to grow their crops (that feed and sustain us) with less water. This continues to be a bigger challenge as the drought grows more severe.

It's not hopeless, though. There are steps farmers can take to prepare to give their crops the best chance for success in hard times. Farmers can change the time of year when they plant crops, or in extreme cases, can switch over to other more drought-tolerant crops to remain profitable.

But making these big decisions requires detailed knowledge about how much water there is on a farm and how much water there might be in the future. One of the most important things to know is the amount of moisture in the soil where their crops grow.

New Challenges and New Tools

In the past, the best way for farmers to figure out this sort of thing was to put sensors in the ground all around their fields-a time-consuming and expensive process. Otherwise, farmers simply relied on their experience and observations.

But soon there will be a new way to look at soil moisture-from space! NASA has a new satellite called Soil Moisture Active Passive (SMAP for short) that can measure soil moisture using special kinds of sensors (or instruments). While there have already been satellites that measure soil moisture, this one will be a big improvement. It will calculate soil moisture across the entire globe every three days and with a high level of detail too!

Droughts are challenging for everyone. People will have to make big changes in how they use water, and new technology will have to be developed to use water more efficiently. SMAP is just one part of the equation, but it could end up being a really helpful one.

Related NASA Missions

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Rainy days can be a bit of a bummer. For many, a rainy day means being pent up inside and missing out on all kinds of fun outdoor activities. Cancelled baseball games. No afterschool soccer. Who needs that? The state of California does, actually. California is in the middle of its third year of intense drought.

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Nearly every part of the U.S. experiences periods of reduced rainfall. Planning in advance for a drought can protect us in dry years.

Before a Drought

The best way to prepare for a drought is to conserve water. Make conserving water a part of your daily life.

Indoor Water Conservation Tips Before a Drought
GENERAL

Never pour water down the drain when there may be another use for it. For example, use it to water your indoor plants or garden.

Fix dripping faucets by replacing washers. One drop per second wastes 2,700 gallons of water a year.

Check all plumbing for leaks and have any leaks repaired by a plumber.

Retrofit all household faucets by installing aerators with flow restrictors.

Install an instant hot water heater on your sink.

Insulate your water pipes to reduce heat loss and prevent them from breaking.

Install a water-softening system only when the minerals in the water would damage your pipes. Turn the softener off while on vacation.

Choose appliances that are more energy and water efficient.

BATHROOM KITCHEN
Outdoor Water Conservation Tips Before a Drought
GENERAL

If you have a well pump, check it periodically. If the automatic pump turns on and off while water is not being used, you have a leak.

Plant native and/or drought-tolerant grasses, ground covers, shrubs and trees. Once established, your plants won't need as much watering. Group plants together based on similar water needs.

Don't install ornamental water features (such as fountains) unless they use re-circulated water.

Consider rainwater harvesting where practical.

Contact your local water provider for information and assistance.

LAWN CARE POOL
During a Drought

Always observe state and local restrictions on water use during a drought. Contact your state or local government for current information and suggestions.

Indoor Water Conservation Tips During a Drought
BATHROOM LAUNDRY KITCHEN
Outdoor Water Conservation Tips During a Drought
LAWN CARE

A heavy rain eliminates the need for watering for up to two weeks. Most of the year, lawns only need one inch of water per week.

Check the soil moisture levels with a soil probe, spade or large screwdriver. You don't need to water if the soil is still moist. If your grass springs back when you step on it, it doesn't need water yet.

If your lawn does require watering, do so early in the morning or later in the evening, when temperatures are cooler.

Water in several short sessions rather than one long one, in order for your lawn to better absorb moisture and avoid runoff.

Use a broom or blower instead of a hose to clean leaves and other debris from your driveway or sidewalk.

Avoid leaving sprinklers or hoses unattended. A garden hose can pour out 600 gallons or more in only a few hours.

In extreme drought, allow lawns to die in favor of preserving trees and large shrubs.

CAR WASHING

Use a commercial car wash that recycles water.

If you wash your own car, use a shut-off nozzle that can be adjusted down to a fine spray on your hose.

Associated Content

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Planning in advance for a drought can protect us in dry years. Learn what to do before, during, and after a drought. Before a Drought During a Drought Associated Content Nearly every part of the U.S. experiences periods of reduced rainfall. Planning in advance for a drought can protect us in dry years.

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Twinkl Teaching Resources - United States

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Wildfires for Kids | What Causes a Wildfire? | Wildfire Safety Rules | Twinkl USA

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Let's Understand Forest Fires | CBC Kids

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Wildfires are unplanned fires that burn in natural areas like forests, grasslands or prairies. These dangerous fires spread quickly and can devastate not only wildlife and natural areas, but also communities.

Prepare for Wildfires

Stay Safe During

Returning Home After a Wildfire

Additional Resources

Videos

Social Media & Graphics

More Info

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How to prepare for a wildfire, stay safe during a wildfire, and return home safely after a wildfire. Prepare for Wildfires Stay Safe During After a Wildfire Additional Resources Wildfires are unplanned fires that burn in natural areas like forests, grasslands or prairies.

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A wildfire can spread, giving you little time to evacuate to safety. Get the facts about wildfires and learn what to do to keep your loved ones safe!

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sinkholes | science with dr karl | national geographic kids

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A sinkhole is a void in the ground caused by a collapse of the Earth’s surface layer usually when limestone and gypsum shifts from lots of moving water.

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A sinkhole is a hole in the ground that forms when water dissolves surface rock.

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What are sinkholes? Sinkholes are pits in the ground that form in areas where water gathers without external drainage. Sinkholes mainly occur as water drains below ground. It can dissolve subterranean caverns, particularly in areas where the bedrock is made of water-soluble evaporate rocks such as salt or gypsum or of carbonate rocks such as limestone or dolomite.What causes sinkholes?Sinkholes can be natural or man made. Natural sinkholes occur due to erosion or underground water. They start developing long time before it actually appears. The ground beneath our feet is not as much of a solid structure as we think it is. The ground is made from dirt, along with many rocks and minerals. There is water continually seeping in between the mud, rocks and minerals, as it makes its way down to the ground water reservoirs. As this happens, the water slowly erodes the rocks and minerals. Sometimes the flow of water increases to a point when it washes away the underground structure of the land. And when the structure becomes too weak to support the surface of the earth, it collapses and opens up a hole. This is how sinkholes are formed.What type of bedrock is more susceptible to sinkholes?Areas that have a bedrock made of limestone, salt deposits or carbonate rock are most susceptible to erosion and the formation of such holes. These rocks tend to erode as acidic water passes through them. When rainwater passes through decaying plant debris, it tend to become more acidic. Over a period of years, overlying sediments collapse and a sinkhole develops. Sometimes the holes are small, measuring a few feet wide and ten to fifteen feet deep. Others can be hundreds of miles wide and deep. However, all of them can be dangerous for those that get caught in them. There are three major kinds of sinkholes. Their formation is determined by the same geological processes, barring a few differences.Can humans cause sinkholes?Yes! Humans are also responsible for the formation of sinkholes. Activities like drilling, mining, construction, broken water or drain pipes, improperly compacted soil after excavation work or even heavy traffic can result in small to large sinkholes. Water from broken pipe can penetrate through mud and rocks and erode the ground underneath and cause sinkholes. Sometimes, heavy weight on soft soil can result in collapse of ground, resulting in a sinkhole. Sinkholes can also form when the land surface is changed.How quickly do sinkholes form?Most of the time, sinkholes form gradually. Occasionally, though, the collapse is sudden. Those sudden sinkholes are often the ones that open up and swallow cars, homes and streets.Why are there so many sinkholes?Most of the sinkholes we are seeing at the moment are at least indirectly created by human activity. They’re occuring just to the sides of human constructions where rain water has been concentrated on a particular patch of ground in the form of run-off from roofs and tarmac. However, these local factors wouldn’t matter if it wasn’t for the wider picture. The Southeast, where most of the sinkholes have appeared, has not only suffered one of the wettest winters in recent decades, but is also natural sinkhole country as most of the bedrock is the soluble chalk.What are some notable sinkholes?In 2010 one of the most devastating sinkholes in recent times hit Guatemala City. An area approximately 65ft wide and 100ft deep collapsed, swallowing a three-story factory and killing 15 people. The sinkhole was caused by a number of factors including an influx of water from Tropical Storm Agatha and leakage from a local sewerage pipe.On February 12, 2014, a sinkhole some 40ft wide and 20ft deep opened under the floor of the Skydome area of the National Corvette Museum causing a portion of the floor to collapse. Eight rare and one-of-a-kind Corvettes, portions of the display stands and rails, large concrete floor slabs and dirt fell into the sinkhole, causing serious damage to some of the Corvettes. The Corvettes involved have an estimated value of a million dollars.Do sinkholes happen in other parts of the world?Yes! The deepest we know about is the Xiaozhai tiankeng in China. Tiankeng is the local term for large sinkholes and translates literally as ‘heavenly pit’. This particular example in the Chongqing district is a staggering 662m deep and 626m wide.Other notable sinkholes include Sima Humboldt in Bolivia, a crater 314m deep and formed from extremely resistant sandstone.The Great Blue Hole in Belize, a perfectly round hole in the middle of an atoll which is 124m deep.Finally, Crveno Jezero in Croatia, a 530m deep sinkhole with nearly vertical walls.

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Rain is pouring hard and fast-more than eight inches in just an hour, turning river water brown with mud. Earthworms wiggle up to the ground as the soil becomes too wet for them. A flood might be coming.

Just about any place on Earth can experience flooding. When so much rain falls that the ground can't absorb it or waterways can't hold it, the overflowing water becomes a destructive force. In the United States, flooding causes more death and damage than tornadoes, hurricanes, or lightning.

How floods develop

During a rainstorm, precipitation-or the water that comes from rain or snow-goes to different places. Some of it flows into streams, lakes, or city water systems. Other precipitation evaporates and returns to the atmosphere.

But much of the rainwater is absorbed by soil. It flows through the top layer of the ground, to plant roots below the surface. This helps provides plants with the water and nutrients they need to grow. The excess water moves deeper into the ground through layers of dirt and rocks where until it becomes part of natural underground wells called groundwater.

A habitat can naturally absorb a healthy amount of rainfall it needs to thrive. But too much rain can cause lake and river levels to rise and overflow their banks, or the soil to become too wet to absorb more water. And though you might think extremely dry habitats would welcome too much rain, it turns out that the parched dirt can't absorb the rain fast enough to capture it all.

Severe coastal storms, quickly melting ice and snow, and collapsed barriers (like concrete dams) can also cause floods. Even damaged beaver dams can lead to an overflow of water that the surrounding earth can't absorb.

Different types of floods

Floods can form slowly over several days or overwhelm an area with little warning. How quickly a flood forms often depends on the habitat.

Slow-forming river flooding happens in regions called floodplains. These are large, flat areas of land along waterways with very shallow banks. When big storms hit, the water overflows the banks and spreads out across the plains.

This type of flooding isn't always bad. It brings nutrients to the surrounding soil, making it fertile for growing crops. That's why many people live in or near floodplains.

But too much water can destroy crops and damage homes. Rushing water can disrupt ecosystems by moving aquatic plants and animals to other habitats. And if flooding is so severe that it flows into local water treatment facilities, experts must monitor the incoming water to make sure the water is safe.

Another type of flooding is called a flash flood, when a flood happens within six hours of a heavy rainfall-as much as eight inches an hour. With no place to go, the moving water will tear through highways, valleys, and canyons, washing away vehicles, roads, bridges, and houses.

Quickly melting ice and snow can also cause flash flooding, especially when mountain snowmelt overflows the waterways below. On coastlines, hurricane rains cause water levels to rise, and the high winds push that water onto land. Called a storm surge, this also causes flash flooding.

Flooding in the future

Scientists believe that warming temperatures caused by climate change are increasing the risk of floods all over the world, especially in coastal and low-lying areas.

Warmer water changes the patterns of ocean currents, which changes global weather patterns. This means that some places will receive more rainfall than the ground can absorb. Other places will get less rain so the land will be drier-and unable to handle rainfall when it does occur.

Scientists think that climate change could also cause stronger hurricanes, with more rain and higher winds causing bigger storm surges. A warmer climate could also mean more snowmelt overwhelming the soil; melting polar ice could cause sea levels to rise and increase flooding. ( Find out how you can help slow climate change.)

How to survive a flood

Experts might issue a flash flood watch if weather conditions are right. It doesn't mean flooding will happen but that meteorologists want people to be prepared. When experts are sure a flash flood is on the way, they issue a warning so people can evacuate immediately. Here's how to keep you and your family safe.

Before a flood
* Know your neighborhood. Research how close you are to streams, drainage channels, canyons, and any other low-lying areas that might flood.
* Keep emergency contact phone numbers in one place so you can get in touch with family members.
* Put together an evacuation plan and share it with everyone in your household. Know what paths and routes you can use to quickly get to a high, dry place.
* Conduct flood drills to practice evacuating quickly.
* Maintain an emergency kit with a three-day supply of food and water. Experts recommend canned or dried foods that don't need to be cooked, and at least one gallon of water per day for each person and pet.

During a flood
* Never wait for orders to leave; if you think a flood might be coming, evacuate immediately.
* If flooding hasn't started, move important items to upper floors of your house.
* If flooding has already started where you are, move to the highest place you can find, like a roof of a house or car. Bring as much food, water, and sheltering blankets as possible.
* Never walk through flood water, especially if it's moving. Hazardous chemicals, sewage, and even wild animals are often in floodwater, and just six inches of moving water can knock you off your feet.
* If you must walk through water to escape, walk where the water is still. Never touch electrical equipment if you are standing in water, or even if you're wet.
* If water is quickly rising while you're in your car, leave your vehicle and move to higher ground, like a hill or bridge.

After a flood
* If you've evacuated your house, return only after you're given the all-clear from officials.
* If you stayed put, check your house for damage to electrical systems and appliances. Get rid of any food that might be contaminated from floodwater (or because it's been unrefrigerated for awhile).
* Check your home for wild animals, especially snakes. They can get washed into your home with the floodwater.
* Ask an adult before you use water to brush your teeth, make food, or even wash your hands. Flooding can contaminate water and make you sick.
Learn more about floods at National Geographic.
Flood safety tips from the Nat Geo Kids book Extreme Weather by Thomas Kostigen

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Learn about what causes flooding, different types of floods-and how to stay safe.

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Most often flooding is caused by heavy rains over a long period of time. After a lot of rain, the ground becomes full of water, and new rainwater runs off, or flows downhill. That runoff goes directly into streams and rivers. In springtime the rain may be combined with melting snow. Because of the extra water flowing into the streams and rivers, their water level rises. If the level rises so much that the water overflows the banks, a flood occurs.

Flooding can be worse if there is not much vegetation (trees, grass, and other plants) on the land around rivers. In general, land that has little vegetation is less able to absorb water. The result is a larger amount of water entering a river system.

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When water overflows onto dry land, a flood takes place. Floods have always been a part of life on Earth. Almost every culture has a legend about a great flood. Since ancient...

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What causes flooding? - National Geographic Kids

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Causes of floods: Why is it that some places flood and some don’t? Well, turns out its all in the geography. Post Boxing Day floods, one school decided to investigate

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Flooding is when a lot of water overflows onto land that is normally dry. It is the most common natural-weather event. Flooding can happen during heavy rains, when rivers overflow, when ocean waves come on the shore, when snow melts too fast, or when dams or levees break. Flooding may be only a few inches of water, or it may cover a house to the rooftop. Floods that happen very quickly are called flash floods. Floods can cause power outages, disrupt transportation, damage buildings, and create landslides.

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Did you know?

Flooding can wash out walkways, roads, and fields, making them impossible to detect under flood water. Do not walk or ride in a car through water. It might be deeper than you think! A foot of water can sweep a vehicle off the road. Stay away from moving water!

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Words to Know Am I at Risk? What Can I Do? Learn More