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Check out our amazing science videos for kids. Learn more about the world around you while watching a range of awesome clips.

Weather Videos

Check out these cool weather videos and see some spectacular natural phenomena in action. Witness huge storms, heavy rain, powerful tornadoes, intense lightning, dust storms, dangerous plane landings, giant hail and other extreme conditions in these amazing weather video clips.

Dust Storm

This amazing video clip shows a giant dust storm in Australia. The dust storm gathers dirt and other small particles as it moves across the dry land.

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Weather Videos - Amazing Weather Video Clips, Extreme Conditions

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Check out our amazing science videos for kids. Learn more about the world around you while watching a range of awesome clips. Weather Videos Check out these cool weather videos and see some spectacular natural phenomena in action.

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Water is one of the most useful things on Earth. We drink it, bathe in it, clean with it and use it to cook food. Most of the time, it is completely benign. But in large enough quantities, the very same stuff we use to rinse a toothbrush can overturn cars, demolish houses and even kill.

Flooding has claimed millions of lives in the last hundred years alone, more than any other weather phenomenon. Hurricane Katrina in New Orleans and the 2008 cyclone that struck Myanmar are recent examples of the widespread devastation that flooding can incur.

In this article, we'll find out what makes water change character so rapidly and see what happens when it does. We'll explore the negative impact of floods as well as some of the benefits. We'll also examine how human construction can contain flooding or, in some cases, cause it.

Water, Water Everywhere

To understand how floods work, you have to know something about how water behaves on our planet. The total amount of water on Earth has remained fairly constant for millions of years (though its distribution has varied considerably in that time). Every day, a very small amount of water is lost high in the atmosphere, where intense ultraviolent rays can break a water molecule apart, but new water is also emitted from the inner part of the Earth, by volcanic activity. The amount of water that is created and the amount that is lost are pretty much equal.

At any one time, this volume of water is in many different forms. It can be liquid, as in oceans, rivers and rain; solid, as in the glaciers of the North and South Poles; or gaseous, as in the invisible water vapor in the air. Water changes from state to state as it is moved around the planet by wind currents. Wind currents are generated by the heating activity of the sun. The sun shines more on the area around Earth's equator than it does on areas farther north and south, causing a heat discrepancy over the surface of the globe. In warmer regions, hot air rises up into the atmosphere, pulling cooler air into the vacated space. In cooler regions, cold air sinks, pulling warmer air into the vacated space. The rotation of the Earth breaks this cycle up, so there are several, smaller air-current cycles all along the globe.

Driven by these air-current cycles, Earth's water supply moves in a cycle of its own. When the sun heats the oceans, liquid water from the ocean's surface evaporates into water vapor in the air. The sun heats this air (water vapor and all) so that it rises through the atmosphere and is carried along by wind currents. As this water vapor rises, it cools down again, condensing into droplets of liquid water (or crystals of solid ice). Collections of these droplets are called clouds. If a cloud moves into a cooler environment, more water may condense onto these droplets. If enough water accumulates in this way, the droplets become heavy enough that they fall through the air as precipitation (rain, snow, sleet or hail). Some of this water collects in large, underground reservoirs, but most of it forms rivers and streams that flow into the oceans, bringing the water back to its starting point.

Overall, wind currents in the atmosphere are fairly consistent. At any particular time of year, currents tend to move in a certain way across the globe. Consequently, specific locations generally experience the same sort of weather conditions year to year. But on a day-to-day basis, the weather is not so predictable. Wind currents and precipitation are affected by many factors, chiefly geography and neighboring weather conditions. A huge number of factors combine in an infinite variety of ways, producing all sorts of weather. Occasionally, these factors interact in such a way that an atypical volume of liquid water collects in one area. For example, conditions occasionally cause the formation of a hurricane, which dumps a large quantity of rain wherever it goes. If a hurricane lingers over a region, or multiple hurricanes happen to move through the area, the land receives much more precipitation than normal.

Since waterways are formed slowly over time, their size is proportionate to the amount of water that normally accumulates in that area. When there is suddenly a much greater volume of water, the normal waterways overflow, and the water spreads out over the surrounding land. At its most basic level, this is what a flood is -- an anomalous accumulation of water in an area of land.

A series of storms bringing massive amounts of rain is the most common cause of flooding, but there are others. In the next section, we'll look at some of the ways floods start, as well as some of the factors that determine their magnitude.

In the last section, we saw that floods occur when an atypical volume of water collects in an area. There are a number of ways this might happen, and there are a wide range of events that occur when it does.

The sort of flooding that most people are familiar with occurs when an unusually large number of rainstorms hit an area in a fairly short period of time. In this case, the rivers and streams that divert the water to the ocean are simply overwhelmed. The varying temperatures of different seasons leads to different weather patterns. In the winter, for example, the air over the ocean might be warmer than the air over the land, causing the wind flow to move from the land out to sea. But in the summer, the air over the land heats up, becoming warmer than the air over the ocean. This causes the wind current to reverse, so that more water from the ocean is picked up and carried over land. This monsoon wind system can cause a period of intense rain that is completely out of step with the climate the rest of the year. In some areas, this flooding may be exacerbated by excess water from melting snow.

Perhaps the best known example of seasonal flooding is the annual expansion of the Nile River in Egypt. In Ancient Egypt, monsoon rains at the source of the river would cause the waterway to extend out a good distance during the summer. In this case, the flooding was not a disaster, but a godsend. The expanding waters would leave fertile silt all along the banks of the river, making the area ideal farming land once the river had subsided again. This is one of the main factors that allowed civilization to thrive in the Egyptian desert. These days, the river is blocked off by a dam upstream, which collects the summer rain and doles it out throughout the year. This has extended the planting season so that Egyptian farms can grow crops year-round.

Another common source of flooding is unusual tidal activity that extends the reach of the ocean farther inland than normal. This might be caused by particular wind patterns that push the ocean water in an unusual direction. It can also be caused by tsunamis, large waves in the ocean triggered by a shift in the Earth's crust.

Floods may also occur when a man-made dam breaks. We build dams to modify the flow of rivers to suit our own purposes. Basically, the dam collects the river water in a large reservoir so that we can decide when to increase or decrease the river's flow, rather than letting nature decide. Engineers build dams that will stand up to any amount of water that is likely to accumulate. Occasionally, however, more water accumulates than the engineers predicted, and the dam structure breaks under pressure. When this happens, a massive amount of water is released all at once, causing a violent "wall" of water to push across the land. In 1889, such a flood occurred in Johnstown, Pennsylvania. The townspeople were warned that the flood was coming, but many dismissed the alert as unfounded panic. When the rushing wall of water did hit, more than 2,000 people were killed in only a few minutes.

The severity of a flood depends not only on the amount of water that accumulates in a period of time, but also on the land's ability to deal with this water. As we've seen, one element of this is the size of rivers and streams in an area. But an equally important factor is the land's absorbency. When it rains, soil acts as a sort of sponge. When the land is saturated -- that is, has soaked up all the water it can -- any more water that accumulates must flow as runoff.

Some materials become saturated much more quickly than others. To see how this works, just take a bucket of water outside and try wetting various surfaces. Soil in the middle of the forest is an excellent sponge. You could dump several buckets of water on it and it would soak the water right up. Rock is not so absorbent -- it doesn't seem to soak up any water at all. Hard clay falls somewhere in between. Generally, soil that has been tilled for crops is less absorbent than uncultivated land, so farm areas may be more likely to experience flooding than natural areas.

One of the least absorbent surfaces around is concrete. In the next section, we'll see how concrete, asphalt and other human construction can affect flooding.

In the last section, we saw that the degree of flooding is determined by the amount of water that accumulates in an area, as well as the nature of the land surface. As civilization has expanded, human beings have altered the landscape in a number of ways. In the Western World, one of the most significant changes has been covering the ground in asphalt and concrete. Obviously, these surfaces are not the best sponges around: Almost all rain that accumulates becomes runoff. In an industrialized area without a good drainage system, it may not take much rain to cause significant flooding.

Some cities, such as Los Angeles, have constructed concrete flood-relief channels to prevent this problem. When it rains a lot, the water flows into these channels, which meander out of the city where the water can be better absorbed. These sorts of systems may cause flooding farther down the line, however. When you cover an area in concrete and asphalt, you are essentially cutting off part of the Earth's natural sponge, so the rest of the sponge has a lot more water to deal with.

A similar problem can arise with levees, large walls built along rivers to keep them from overflowing. These structures extend the natural banks of the river so that much more water can flow through it. But while they may be effective at keeping water out of one area, they usually make problems worse for an area down the line, where there are no levees. That area gets all the flood waters that would have spread out farther up river. Another danger of levees is that, like dams, they can break. When this happens, a large amount of water flows out onto the land in a short period of time. This can cause some of the most dangerous flood conditions.

People haven't had much success with controlling flooding along coastlines. Excessive water in these areas is particularly destructive to man-made structures because of the erosion it causes. One method of controlling this erosion is to build fences and walls where the water meets the land. This keeps the power of the waves at bay, so they don't wear down the beach. But the structures also interfere with the process of beach formation. When you block the water from moving against the coast, the ocean can't distribute sand and you don't get beautiful beaches.

Another problem with fences and walls is that there is only so much they can do. Fundamentally, beaches are changing environments, molded by the overpowering force of the ocean. They are, by their very nature, supposed to be eroded and moved by the dynamic action of waves. Flooding is a regular part of this process, and most likely will continue to be no matter what we do.

The same can be said for many inland areas. While a river may appear to us to be a stable, unmovable feature of the landscape, it is really a vibrant, dynamic entity. This is particularly true of big rivers, such as the Mississippi in the United States and the Yangtze and Huang He in China. Over time, these waterways expand, shift their path dramatically and may even change the direction of flow. For this reason, the land around the banks of a river is highly susceptible to flooding.

Unfortunately, rivers are also natural draws for civilization. Among other things, they provide a constant supply of water, rich soils and an easy means for transportation. When the water level is low, people build all along its banks and enjoy all its benefits. At some point, it comes time for the water to shift, and the people who have built along the flood plains quickly discover that they are living on unsound ground. If there is extensive construction in these areas, the flood damage can be devastating.

In the next section, we'll look at the different sorts of flood damage to see how ordinary water can be a devastating force.

The worst damage from floods, the loss of life and homes, is caused primarily by the sheer force of flowing water. In a flood, two feet (61 cm) of water can move with enough force to wash a car away, and 6 inches (15 cm) of water can knock you off your feet. It may seem surprising that water, even a lot of water, can pack such a wallop. After all, you can peacefully swim in the ocean without being knocked around, and that's a massive amount of moving water. And in most cases, a flowing river isn't strong enough to knock you over. So why do flood waters behave differently?

Flood waters are more dangerous because they can apply much more pressure than an ordinary river or a calm sea. This is due to the massive differences in water volume that exist during many floods. In a flood, a lot of water may collect in an area while there is hardly any water in another area. Water is fairly heavy, so it moves very quickly to "find its own level." The bigger the difference between water volumes across an area, the greater the force of movement. But at a particular point, the water doesn't look so deep, and so doesn't seem particularly dangerous -- until it's too late. Nearly half of all flood deaths result from people attempting to drive their cars through rushing water. There is much more water in the ocean than in a flood, but it doesn't knock us over because it is fairly evenly distributed -- water in a calm sea isn't rushing to find its own level.

The most dangerous floods are flash floods, which are caused by a sudden, intense accumulation of water. Flash floods hit an area soon after water begins to accumulate (whether from excessive rain or another cause), so a lot of the time, people don't see them coming. Since there is a great deal of water collected in one area, flash-flood waters tend to move with a great deal of force, knocking people, cars and even houses out of the way. Flash floods can be particularly devastating when a heavy thunderstorm dumps a high volume of rain on a mountain. The water moves down the mountain at tremendous speed, plowing through anything in the valleys below.

One of the worst flash floods in U.S. history occurred in 1976, in Big Thompson Canyon, Colorado. In less than five hours, thunderstorms in nearby areas dumped more rain than the region ordinarily experiences in a year. The Big Thompson River, normally a shallow, slow-moving waterway, abruptly transformed into an unstoppable torrent, dumping 233,000 gallons (882,000 L) of water into the canyon every second. Thousands of campers had gathered in the canyon to celebrate the centennial of the state of Colorado. The flood happened so quickly that there was no time to issue a warning. When it hit, hundreds of people were injured, and 139 were killed.

A less catastrophic sort of damage is simple dampness. Most buildings can keep out the rain, but they aren't built to be water-tight. If the water level is high enough, loads of water seeps into houses, soaking everything. But in most cases, the major damaging element is not the water itself, but the mud it brings with it. As water flows over the landscape, it picks up a lot of junk. When the flood is over, the water level drops and everything eventually dries out, but the mud and debris stick around.

In 1966, a major storm flooded the Arno, an Italian river that runs through the city of Florence. The small city, one of the art capitals of the world, was overrun with water, mud and general slime. In addition to the loss of life and the damage to buildings, there was a great deal of damage to the city's art collection. Mud and slime covered almost everything stored in the city's basements and ground-level rooms. Through many years of work, scientists and art historians have been able to restore most of the damaged artifacts to good condition.

Another sort of flood damage is the spread of disease. As water flows over an area, it can pick up all sorts of chemicals and waste products, leading to extremely unsanitary conditions. Essentially, everything and everyone in a flood is floating along in one big soup. While diseases usually aren't created by these conditions, they are more easily transferred (most diseases spread through water more readily than they move through the air). If you are in a flooded area, it is very important that you drink only bottled or boiled water and observe other sanitation guidelines. To learn more about what to do in flooded conditions, check out this guide put out by the Center for Disease Control.

We'll never be able to stop flooding. It is an unavoidable element in the complex weather system of our atmosphere. We can, however, work to minimize the damage inflicted by flooding, by building sophisticated dams, levees and canal systems. But the best way to avoid flood damage may be to back out of flood-prone areas altogether. As with many natural phenomena, the most sensible reaction to flooding may be to get out of the way.

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Water is one of the most useful things on Earth. We drink it, bathe in it, clean with it and use it to cook food. Most of the time, it is completely benign. But in large enough quantities, the very same stuff we use to rinse a toothbrush can overturn cars, demolish houses and even kill.

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What is wind?
Wind is air in motion. It is produced by the uneven heating of the earth's surface by the sun. Since the earth's surface is made of various land and water formations, it absorbs the sun's radiation unevenly. Two factors are necessary to specify wind: speed and direction.

What causes the wind to blow?
As the sun warms the Earth's surface, the atmosphere warms too. Some parts of the Earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cold air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.

What is a windstorm?
A windstorm is just a storm with high winds or violent gusts but little or no rain.

What are damaging winds?
Damaging winds are often called "straight-line" winds to differentiate the damage they cause from tornado damage. Strong thunderstorm winds can come from a number of different processes. Most thunderstorm winds that cause damage at the ground are a result of outflow generated by a thunderstorm downdraft. Damaging winds are classified as those exceeding 50-60 mph.

Are damaging winds really a big deal?
Damage from severe thunderstorm winds account for half of all severe reports in the lower 48 states and is more common than damage from tornadoes. Wind speeds can reach up to 100 mph and can produce a damage path extending for hundreds of miles.

Who is at risk from damaging winds?
Since most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft, anyone living in thunderstorm-prone areas of the world is at risk for experiencing this hazard. People living in mobile homes are especially at risk from injury and death. Even anchored mobile homes can be seriously damaged when winds gust over 80 mph.

What is a gust front?
A gust front is the leading edge of cool air rushing down and out from a thunderstorm. There are two main reasons why the air flows out of some thunderstorms so rapidly. The primary reason is the presence of relatively dry air in the lower atmosphere. This dry air causes some of the rain falling through it to evaporate, which cools the air. Since cool air sinks (just as warm air rises), this causes a down-rush of air that spreads out at the ground. The edge of this rapidly spreading cool pool of air is the gust front. The second reason is that the falling precipitation produces a drag on the air, forcing it downward. If the wind following the gust front is intense and damaging, the windstorm is known as a downburst.

What is a downburst?
A downburst is created by an area of significantly rain-cooled air that, after hitting ground level, spreads out in all directions producing strong winds. Unlike winds in a tornado, winds in a downburst are directed outwards from the point where it hits land or water. Dry downbursts are associated with thunderstorms with very little rain, while wet downbursts are created by thunderstorms with high amounts of rainfall.

What is a derecho?
A derecho is a widespread and long-lived windstorm that is associated with a fast-moving band of severe thunderstorms. They can produce significant damage to property and pose a serious threat life, primarily by downburst winds. To be classified as a derecho, the path length of the storm has to be at least 280 miles long. Widths may vary from 50-300 miles. Derechos are usually not associated with a cold front, but a stationary front. They occur mostly in July, but can occur at anytime during the spring and summer.

What is a dust devil?
A dust devil generally forms in the hot sun during the late morning or early afternoon hours. These are mostly harmless whirlwinds and are triggered by light desert breezes that create a swirling plume of dust with speeds rarely over 70 mph. These differ from tornadoes in that they are not associated with a thunderstorm (or any cloud) and are usually very weak.

What is the jet stream?
The jet stream is a fast flowing, river of air found in the atmosphere at around 12 km above the surface of the Earth just under the tropopause. They form at the boundaries of adjacent air masses with significant differences in temperature, such as of the polar region and the warmer air to the south. Because of the effect of the Earth's rotation the streams flow west to east, propagating in a serpentine or wave-like manner at lower speeds than that of the actual wind within the flow.

How is wind helpful to Earth?
Wind is the fastest growing source of electricity in the world. It's often one of the least expensive forms of renewable power available. Some experts say it can sometimes be the cheapest form of any kind of power. Generating power from the wind leaves no dangerous waste products behind. Best of all, its supply is unlimited.

How do windmills work?
Windmills work because they slow down the speed of the wind. The wind flows over the airfoil shaped blades causing lift, like the effect on airplane wings, causing them to turn. The blades are connected to a drive shaft that turns an electric generator to produce electricity.

What are the global wind patterns?
The equator receives the Sun's direct rays. Here, air is heated and rises, leaving low pressure areas behind. Moving to about thirty degrees north and south of the equator, the warm air from the equator begins to cool and sink. Between thirty degrees latitude and the equator, most of the cooling sinking air moves back to the equator. The rest of the air flows toward the poles.

What are the trade winds?
The trade winds are just air movements toward the equator. They are warm, steady breezes that blow almost continuously. The Coriolis Effect makes the trade winds appear to be curving to the west, whether they are traveling to the equator from the south or north.

What are the doldrums?
The doldrums is an area of calm weather. The trade winds coming from the south and the north meet near the equator. These converging trade winds produce general upward winds as they are heated, so there are no steady surface winds.

What are the prevailing westerlies?
Between thirty and sixty degrees latitude, the winds that move toward the poles appear to curve to the east. Because winds are named from the direction in which they originate, these winds are called prevailing westerlies. Prevailing westerlies in the Northern Hemisphere are responsible for many of the weather movements across the United States and Canada.

What are the polar easterlies?
At about sixty degrees latitude in both hemispheres, the prevailing westerlies join with the polar easterlies to reduce upward motion. The polar easterlies form when the atmosphere over the poles cools. This cool air then sinks and spreads over the surface. As the air flows away from the poles, it is turned to the west by the Coriolis effect. Again, because these winds begin in the east, they are called easterlies.

What is a monsoon?
A monsoon is a seasonal wind, found especially in Asia that reverses direction between summer and winter and often brings heavy rains. In the summer, a high pressure area lies over the Indian Ocean while a low exists over the Asian continent. The air masses move from the high pressure over the ocean to the low over the continent, bringing moisture-laden air to south Asia. During winter, the process is reversed and a low sits over the Indian Ocean while a high lies over the Tibetan plateau so air flows down the Himalaya and south to the ocean. The migration of trade winds and westerlies also contributes to the monsoons. Smaller monsoons take place in equatorial Africa, northern Australia, and, to a lesser extent, in the southwestern United States.

What are the Santa Ana Winds?
The Santa Ana winds are strong, extremely dry down-slope winds that originate inland and affect coastal Southern California and northern Baja California. Santa Ana winds blow mostly in autumn and winter, but can arise at other times of the year. They can range from hot to cold, depending on the prevailing temperatures in the source regions, the Great Basin and upper Mojave Desert. The winds are known especially for the hot dry weather (often the hottest of the year) that they bring in the fall, and are infamous for fanning regional wildfires. For these reasons, they are sometimes known as the "devil winds" across Southern California.

What is a sea breeze?
On a warm summer day along the coast, this differential heating of land and sea leads to the development of local winds called sea breezes. As air above the land surface is heated by radiation from the Sun, it expands and begins to rise, being lighter than the surrounding air. To replace the rising air, cooler air is drawn in from above the surface of the sea. This is the sea breeze, and can offer a pleasant cooling influence on hot summer afternoons.

What is a land breeze?
A land breeze occurs at night when the land cools faster than the sea. In this case, it is air above the warmer surface water that is heated and rises, pulling in air from the cooler land surface.

What are some different types of wind names?
Many local wind systems have their own names. Here's a few!

chinook- (westerly wind off the eastern side of the Rocky Mountains)

santa ana- (easterly towards Southern California )

scirocco- (southerly from North Africa to southern Europe)

mistral- (northwesterly from central France to Mediterranean)

marin- (southeasterly from Mediterranean to France)

bora- (northeasterly from eastern Europe to Italy)

gregale- (northeasterly from Greece)

etesian- (northwesterly from Greece)

libeccio- (southwesterly towards Italy)

The Beaufort Scale is an empirical measure for the intensity of the weather based mainly on wind power. The scale was created by the British naval commander Sir Francis Beaufort around 1806 and goes from 0 to 12.

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What is wind? Wind is air in motion. It is produced by the uneven heating of the earth's surface by the sun. Since the earth's surface is made of various land and water formations, it absorbs the sun's radiation unevenly. Two factors are necessary to specify wind: speed and direction.

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What is a thunderstorm?
A thunderstorm is a storm with lightning and thunder. Its produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail.

What causes a thunderstorm?
The basic ingredients used to make a thunderstorm are moisture, unstable air and lift. You need moisture to form clouds and rain. You need unstable air that is relatively warm and can rise rapidly. Finally, you need lift. This can form from fronts, sea breezes or mountains.

What are the stages of a thunderstorm?
Thunderstorms have three stages in their life cycle: The developing stage, the mature stage, and the dissipating stage. The developing stage of a thunderstorm is marked by a cumulus cloud that is being pushed upward by a rising column of air (updraft). The cumulus cloud soon looks like a tower (called towering cumulus) as the updraft continues to develop. There is little to no rain during this stage but occasional lightning. The thunderstorm enters the mature stage when the updraft continues to feed the storm, but precipitation begins to fall out of the storm, creating a downdraft (a column of air pushing downward). When the downdraft and rain-cooled air spreads out along the ground it forms a gust front, or a line of gusty winds. The mature stage is the most likely time for hail, heavy rain, frequent lightning, strong winds, and tornadoes. Eventually, a large amount of precipitation is produced and the updraft is overcome by the downdraft beginning the dissipating stage. At the ground, the gust front moves out a long distance from the storm and cuts off the warm moist air that was feeding the thunderstorm. Rainfall decreases in intensity, but lightning remains a danger.

What is a Mesoscale Convective System?
A Mesoscale Convective System (MCS) is a collection of thunderstorms that act as a system. An MCS can spread across an entire state and last more than 12 hours. On radar one of these monsters might appear as a solid line, a broken line, or a cluster of cells. This all-encompassing term can include any of the following storm types:

Mesoscale convective complex (MCC)-A particular type of MCS, an MCC is a large, circular, long-lived cluster of showers and thunderstorms identified by satellite. It often emerges out of other storm types during the late-night and early-morning hours. MCCs can cover an entire state.

Mesoscale convective vortex (MCV)-A low-pressure center within an MCS that pulls winds into a circling pattern, or vortex. With a core only 30 to 60 miles wide and 1 to 3 miles deep, an MCV is often overlooked in standard weather analyses. But an MCV can take on a life of its own, persisting for up to 12 hours after its parent MCS has dissipated. This orphaned MCV will sometimes then become the seed of the next thunderstorm outbreak. An MCV that moves into tropical waters, such as the Gulf of Mexico, can serve as the nucleus for a tropical storm or hurricane.

What is SKYWARN?
SKYWARN is a National Weather program that is run by and coordinated by the NWS. It was a concept developed in the early 1970's that was intended to promote a cooperative effort between the National Weather Service and its communities. The emphasis of the effort is often focused on the storm spotter, a volunteer who takes a position near their community and reports wind gusts, hail size, rainfall, and cloud formations that could signal a developing tornado. YOU can be trained to be a SKYWARN spotter. Visit www.skywarn.org to find a link to local SKYWARN groups. If your area is not listed, contact your local National Weather Service Office.

What is lightning?
Lightning is a bright flash of electricity produced by a thunderstorm. All thunderstorms produce lightning and are very dangerous. If you hear the sound of thunder, then you are in danger from lightning. Lightning kills and injures more people each year than hurricanes or tornadoes; between 75 to 100 people.

What causes lightning?
Lightning is an electric current. Within a thundercloud way up in the sky, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of those collisions create an electric charge. After a while, the whole cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud. Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes!

Have you ever rubbed your feet across carpet and then touched a metal door handle? If so, then you know that you can get shocked! Lightning works in the same way.

Click Here to see where lightning is currently striking across the U.S.

What causes thunder?
Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. Once then light is gone the air collapses back in and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!

How do you know if lightning is nearby?
If you see dark clouds, then lightning could be present, but the best thing you can do is to listen for thunder. If you hear thunder, then you need to go indoors or get in a car. Don't be outside, where lightning could strike! If your hair stands on end or your skin starts to tingle, lightning maybe about to strike. Get down on your hands and knees and keep your head tucked in. Do not lay flat, because it can give lightning a better chance of strike you.

What is hail?
Hail is a variety of differently shaped ice balls or lumps. Hail or hailstones are made up of water ice and can be any size; it can be measured anything from five millimetres and two hundred millimeters. Hail is produced during thunderstorms and heavy rains.

What is a hailstorm?
A hailstorm is a thunderstorm that produces hail.

How does hail form?
Hail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher and higher into the sky until they freeze into ice. Once they become heavy, they will start to fall. If the smaller hailstones get caught in the updraft again, they will get more water on them and get lifted higher in the sky and get bigger. Once they get lifted again, they freeze and fall. This happens over and over again until the hailstone is too heavy and then falls to the ground.

How does hail fall to the ground?
Hail falls when it becomes heavy enough to overcome the strength of the updraft and is pulled by gravity towards the earth. How it falls is dependent on what is going on inside the thunderstorm. Hailstones bump into other raindrops and other hailstones inside the thunderstorm, and this bumping slows down their fall. Drag and friction also slow their fall, so it is a complicated question! If the winds are strong enough, they can even blow hail so that it falls at an angle. This would explain why the screens on one side of a house can be shredded by hail and the rest are unharmed!

How is hail measured?
Hail size is estimated by comparing it to a known object. Most hail storms are made up of a mix of sizes, and only the very largest hail stones pose serious risk to people caught in the open.

Pea = 1/4 inch diameter

Marble/mothball = 1/2 inch diameter

Dime/Penny = 3/4 inch diameter

Nickel = 7/8 inch

Quarter = 1 inch - hail quarter size or larger is considered severe

Ping-Pong Ball = 1 1/2 inch

Golf Ball = 1 3/4 inches

Tennis Ball = 2 1/2 inches

Baseball = 2 3/4 inches

Tea cup = 3 inches

Grapefruit = 4 inches

Softball = 4 1/2 inches

What causes the wind to blow?
As the sun warms the Earth's surface, the atmosphere warms too. Some parts of the Earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cold air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.

What are the different types of microbursts?
There are two kinds of microbursts: wet and dry. A wet microburst is accompanied by heavy precipitation at the surface. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground.

What is a gust front?
A gust front is the leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.

What is a bow echo?
A bow echo is a radar echo that is linear but bent outward in a bow shape. Damaging straight-line winds often occur near the "crest" or center of a bow echo. Areas of circulation also can develop at either end of a bow echo, which sometimes can lead to tornado formation - especially in the left (usually northern) end, where the circulation shows cyclonic rotation.

SEVERE THUNDERSTORM WATCH - A severe thunderstorm (damaging winds of 58 miles per hour or more, or 1″ hail in diameter or greater) is likely to develop in your area.

SEVERE THUNDERSTORM WARNING - A severe thunderstorm (damaging winds of 58 miles per hour or more, or hail three-fourths of an inch in diameter or greater) is taking place in your area.

DOWNDRAFT - A sudden descent of cool or cold air to the ground, usually with precipitation, and associated with a thunderstorm or shower.

UPDRAFT - A warm column of air that rises within a cloud. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud.

The typical thunderstorm is 15 miles in diameter and lasts an average of 30 minutes.

Thunderstorms happen in every state and every thunderstorm has lightning.

Thunderstorms may occur singly, in clusters, or in lines.

Some of the most severe occur when a single thunderstorm affects one location for an extended time.

Thunderstorms typically produce heavy rain for a brief period, anywhere from 30 minutes to an hour.

Warm, humid conditions are highly favorable for thunderstorm development.

About 10 percent of thunderstorms are classified as severe-one that produces hail at least three-quarters of an inch in diameter, has winds of 58 miles per hour or higher, or produces a tornado.

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

IF YOU'RE OUTDOORS: Keep an eye at the sky. Look for darkening skies, flashes of lightning, or increasing winds. Lightning often proceeds rain, so don't wait for the rain to begin. If you hear the sound of thunder, go to a safe place immediately. The best place to go is a sturdy building or a car, but make sure the windows in the car are shut. Avoid sheds, picnic areas, baseball dugouts and bleachers.

If there is no shelter around you, stay away from trees. Crouch down in the open area, keeping twice as far away from a tree as far as it is tall. Put your feet together and place your hands over your ears to minimize hearing damage from thunder. If you're with a group of people stay about 15 feet from each other. Stay out of water, because it's a great conductor of electricity. Swimming, wading, snorkeling and scuba diving are not safe. Also, don't stand in puddles and avoid metal. Stay away from clotheslines, fences, and drop your backpacks because they often have metal on them. If you're playing an outdoor activity, wait at least 30 minutes after the last observed lightning strike or thunder.

IF YOU'RE INDOORS: Avoid water. It's a great conductor of electricity, so do not take a shower, wash your hands, wash dishes or do laundry. Do not use a corded telephone. Lightning may strike exterior phone lines. Do not use electric equipment like computers and appliances during a storm. Stay away from windows and doors and stay off porches.

IF SOMEONE IS STRUCK BY LIGHTNING: Call for help. Call 9-1-1 or send for help immediately. The injured person does not carry an electrical charge, so it is okay to touch them.

Make Lightning In Your Mouth Experiment: Here is a great experiment that allows kids to make lightning in their mouth. It's a great way for them to understand how lightning works.

What's Lightning Experiment: Here is a great experiment that allows the kids to make lightning. All you need is a balloon and a light bulb!

Make Lightning Experiment: Here is another great experiment that allows the kids to make lightning. This teaches kids about the positive and negative charges and where they come from.

Sticking A Balloon To A Wall Experiment: Here is an experiment that allows the kids to learn about static electricity by sticking a balloon to a wall. This teaches kids about the positive and negative charges and where they come from.

Bend Water Experiment: Here is another static electricity experiment that bends water. This teaches kids about the positive and negative charges and where they come from.

Make Your Hair Stand Up Experiment: Here is yet another static electricity experiment with using a balloon and your hair. This teaches kids about the positive and negative charges and where they come from.

Make Thunder Experiment: This experiment allows kids to make thunder, in a way that allows them to understand how it is made by lightning.

Track A Thunderstorm Experiment: Here is a great way to teach kids how to track a thunderstorm.

Make A Thunderstorm Experiment: Here is a great experiment that shows kids how our weather works. It teaches them how thunderstorms are formed!

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.

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What is a thunderstorm? A thunderstorm is a storm with lightning and thunder. Its produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. What causes a thunderstorm? The basic ingredients used to make a thunderstorm are moisture, unstable air and lift. You need moisture to form clouds and rain.

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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.

How do hurricanes form?
Hurricanes only form over really warm ocean water of 80°F or warmer. The atmosphere (the air) must cool off very quickly the higher you go. Also, the wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface. Winds flow outward above the storm allowing the air below to rise. Hurricanes typically form between 5 to 15 degrees latitude north and south of the equator. The Coriolis Force is needed to create the spin in the hurricane and it becomes too weak near the equator, so hurricanes can never form there.
Hurricane Tracking Charts
Atlantic Ocean
Eastern Pacific

What is storm surge?
Storm surges are frequently the most devastating element of a hurricane. As a hurricane's winds spiral around and around the storm, they push water into a mound at the storm's center. This mound of water becomes dangerous when the storm reaches land because it causes flooding along the coast. The water piles up, unable to escape anywhere but on land as the storm carries it landward. A hurricane will cause more storm surge in areas where the ocean floor slopes gradually. This causes major flooding.
As you watch the storm-surge animations, notice the effect that the physical geography of each coastline has on storm surge. Also, note the waves on top of the ocean's surface. Wind, waves, and sea-level rise all contribute to storm-surge damage.

Shallow-Water Coastline

Deep-Water Coastline

With technology the way it is, there are computer models that allow forecasters to predict the amount of storm surge that will affect a coastal area. These are called Slosh Models and take into account a storm's strength, its path, how the ocean shallows, and the shape of the land. Then it calculates how much storm surge a hurricane will probably cause.

When does hurricane season start?
The Atlantic hurricane season is from June 1 to November 30, but most hurricanes occur during the fall months. The Eastern Pacific hurricane season is from May 15 to November 30. (Below is a graphic that shows you when hurricanes are most active across parts of the world.)

Who names hurricanes?
From 1950 to 1952, tropical cyclones of the North Atlantic Ocean were identified by the phonetic alphabet (Able-Baker-Charlie-etc.), but in 1953 the US Weather Bureau switched to women's names. The rest of the world eventually caught on, and naming rights now go by the World Meteorological Organization, which uses different sets of names depending on the part of the world the storm is in. Around the U.S., only women's names were used until 1979, when it was decided that they should alternate a list that included men's names too. There's 6 different name lists that alternate each year. If a hurricane does significant damage, its name is retired and replaced with another.
Atlantic Hurricane Names
Eastern Pacific Hurricane Names

What is the difference between a hurricane and a typhoon?
Nothing except geography. Tropical storms occur in several of the world's oceans, and except for their names, they are essentially the same type of storm. In the Atlantic Ocean, Gulf of Mexico, and the Eastern Pacific Ocean, they are called hurricanes. In the Western Pacific Ocean, they are called typhoons. In the Indian Ocean, the Bay of Bengal, and Australia, these types of storms are called cyclones.

Who are the "Hurricane Hunters"?
The brave "hurricane hunters" work for the National Oceanic and Atmospheric Administration (NOAA). Each mission lasts about ten hours, with the crews passing four to six times through the storm. The planes carry radar, sophisticated computers, and weather instruments that determine characteristics such as temperature, air pressure, wind speed, and wind direction inside the hurricane. The crews also release instruments that measure temperature, air pressure, and wind at different levels as the devices drop through the hurricane toward the ocean. By mission's end, NOAA can warn everyone in the hurricane's path. Below is a photo of the hurricane hunters taking measurements inside Hurricane Katrina.

What is coastal beach erosion?
Coastal beach erosion is the wearing away of land, the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage. Waves are generated by storms, wind, or hurricanes and can cause coastal erosion. This may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments.

TROPICAL STORM WATCH - Tropical Storm conditions with sustained winds from 39 -74 mph are possible in your area within the next 36 hours.

TROPICAL STORM WARNING - Tropical Storm conditions are expected in your area within the next 24 hours.

HURRICANE WATCH - Hurricane conditions with sustained winds of 74 mph or greater are possible in your area within the next 36 hours. This WATCH should trigger your family's disaster plan, and protective measures should be initiated. Especially, those actions that require extra time such as securing a boat and leaving a barrier island.

HURRICANE WARNING - Hurricane conditions are expected in your area within 24 hours. Once this WARNING has been issued, your family should be in the process of completing protective actions and deciding the safest location to be during the storm.

COASTAL FLOOD WATCH - The possibility exists for the inundation of land areas along the coast within the next 12 to 36 hours.

COASTAL FLOOD WARNING - Land areas along the coast are expected to become, or have become, inundated by sea water above the typical tide action.

SMALL CRAFT ADVISORY - A small craft advisory is a type of warning issued by the National Weather Service, most frequently in coastal areas. It is issued when winds have reached, or are expected to reach within 12 hours, a speed marginally less than that which is considered gale force, usually 25-38 mph.

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

Tropical Wave - A low pressure trough moving generally westward with the trade winds.

Tropical Disturbance - An organized area of thunderstorms that usually forms in the tropics. Typically, they maintain their identity for 24 hours and are accompanied by heavy rains and gusty winds.

Tropical Cyclone - A generic term for any organized low pressure that develops over tropical and sometimes sub-tropical waters. Tropical depressions, tropical storms, and hurricanes are all example of tropical cyclones.

Tropical Depression - An organized area of low pressure in which sustained winds are 38 mph or less.

Tropical Storm - A tropical cyclone with maximum sustained wind speeds that range from 39 to 73 mph.

Hurricane - A tropical cyclone with sustained winds of at least 74 mph.

To learn more about hurricanes, Click Here to watch a variety of videos teaching you the ins and outs of nature's fury. I would like to give a special thanks to Pinellas County Emergency management for putting these instructional videos together.

BEFORE A HURRICANE: Have a disaster plan and a pet plan ready. Before a storm threatens, contact your veterinarian or local humane society for information on preparing your pets for an emergency. Board up windows and bring in outdoor objects that could blow away. Make sure you know which county or parish you live in and know where all the evacuation routes are. Prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food and a can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water. Have a NOAA weather radio handy with plenty of batteries, so you can listen to storm advisories. Have some cash handy as well, because following a hurricane, banks and ATMs may be temporarily closed. Make sure your car is filled with gasoline.

DURING A HURRICANE: Stay away from low-lying and flood prone areas. Always stay indoors during a hurricane, because strong winds will blow things around. Leave mobile homes and to go to a shelter. If your home isn't on higher ground, go to a shelter. If emergency managers say to evacuate, then do so immediately.

AFTER A HURRICANE: Stay indoors until it is safe to come out. Check for injured or trapped people, without putting yourself in danger. Watch out for flooding which can happen after a hurricane. Do not attempt to drive in flooding water. Stay away from standing water. It may be electrically charged from underground or downed power lines. Don't drink tap water until officials say its safe to do so.

Stay alert to storm advisories by using your NOAA weather radio.

Enact your family disaster plan.

Map out your route. Use travel routes specified by local authorities.

Do not get on the road without a place to go.

Fill your car with gasoline.

Enact your pet plan. Before a storm threatens, contact your veterinarian or local humane society for information on preparing your pets for an emergency.

Bring your disaster supply kit. Make sure you include important documents. Have enough food and water for at least 3 days. Bring flashlights for emergency lightning, since it's likely that there will be power outages and most places will be running on backup power.

Secure your home before leaving. Board up windows and glass doors, anchor loose objects or bring them inside and lock your doors.

Have some cash handy. Following a hurricane, banks and ATMs may be temporarily closed.

Notify your family and friends of your plans.

WHEN EVACUATING:

If possible, evacuate to the home of either friends or family in a non-vulnerable area within your county or parish.

Next, try a hotel.

As a last result, go to a public shelter. Remember, shelters are not designed for comfort and do not usually accept pets.

Here is a list of what what you will need for 3 to 5 days if you chose to stay at your home during a hurricane.

Drinking Water Battery-operated Weather Radio

Canned Food Portable Alarm Clock

Manual Can Opener Extra Batteries

Extra Prescription Medicine Flashlights

Eating Utensils Rope

First Aid Kit Hammer and Nails

Trash Bags Duct Tape

Cash Extension Cords

Pillows and Blankets Tarp

Sleeping Bags Mosquito Repellent

Water Jugs Cleaning Supplies

As far as tools are concerned, the following are a must. Remember, power tools may be useless for several days after a storm.

Hand Saw (8 or 10 point)

Claw Hammer

Shovel

Push Broom

Screw Drivers

Limb Saw (pruning saw)

Vice Grips

Utility Knife

Cotton Work Gloves

Lesson Plan: Here is a great lesson plan on learning about hurricane safety. In this activity, Owlie teaches kids about hurricanes and quizzes them about what they learned. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Lesson Plan: Here is a great lesson plan on understanding hurricanes. Students will learn how wind speed increases the height and why higher waves occur in shallower water. This activity is for grades 6-8.

Lesson Plan: Here is a great lesson plan on elementary reading comprehension. This lesson contains a broader vocabulary, more hurricane facts, and more thought-provoking writing prompts. It works well for grades 3-5. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Lesson Plan: Here is a great interactive lesson plan on allowing kids to create their very own hurricane. It lets you try to create ideal hurricane conditions by changing the winds, latitude, moisture, and sea temperature. It even keeps score! This is a great activity for 5-8th graders.

Lesson Plan: Here is a great interactive lesson plan that lets kids aim a hurricane. It lets you move the hurricane symbol, high pressure symbol and low pressure symbol to track your very own hurricane. Sometimes your hurricane will make landfall, other times it misses the U.S. all together. It lets kid understand how important the setup of weather impacts where hurricanes go.

Suck An Egg Into A Bottle 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!

Make Your Own Barometer I Experiment: Here is an experiment that allows the kids to make a barometer.

Make Your Own Barometer II Experiment: Here is an experiment that allows the kids to make a barometer.

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

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.

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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.

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Severe Weather: Crash Course Kids #28.2... - SafeShare

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SafeShare reduces advertisements and other unwanted distractions from Vimeo and YouTube videos, so they can be viewed safely. Perfect for Schools!