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It's a cloudy day on the Kansas plains. You and your dad keep a eye on the skies as you plow the fields. You've seen clouds like these before, and you know that they can be trouble. As the afternoon fades away, you begin to see the clouds form a wall.

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Tornadoes - sometimes called twisters - are columns of air that connect a cumulonimbus cloud with the surface of the Earth. One of the most violent of all weather phenomena, tornadoes are very dangerous and can cause massive damage.

Tornadoes come in all sorts of sizes and shapes. Most often, they take the form of a -shaped cloud with a narrow end touching the Earth. They are usually surrounded by large clouds of and dust.

Most tornadoes feature wind speeds under 110 miles per hour, span about 250 feet in width and only travel a few miles before dissipating . The largest, most destructive tornadoes, though, can boast wind speeds of more than 300 miles per hour, span more than two miles in width and remain on the ground for dozens of miles.

Weather experts use the Fujita scale to rate tornadoes based on the damage they cause. Tornadoes can receive a Fujita scale rating from F0 to F5.

For example, an F0 - the weakest possible - can damage trees but not sturdy structures. On the opposite end of the scale, an F5 - the strongest possible - can tear buildings off their foundations and even deform huge skyscrapers.

" Alley" is a term that the media and weather experts use to refer to the area of the United States where the strongest tornadoes occur most frequently. There is no official definition of Alley, but the area between the Rocky Mountains and the Appalachian Mountains is commonly considered to define the area.

The term was first used by Jennifer Wiley in 1904. The heart of Alley consists of the Texas Panhandle, Oklahoma, Kansas, Nebraska, eastern South Dakota and the Colorado Eastern Plains. Although no state avoids tornadoes entirely, the strongest ones tend to happen in these areas.

Texas reports the most tornadoes annually, but Kansas and Oklahoma report more tornadoes per land area than even Texas. Florida also experiences a high number of tornadoes each year, although they tend to be weaker storms than those in Alley.

Weather experts believe that strong tornadoes occur so frequently in Alley because cold, dry air from Canada and the Rocky Mountains meets warm, moist air from the Gulf of Mexico and hot, dry air from the Sonoran Desert, which is located in the southwestern part of the United States. When these air masses combine with atmospheric instability , they produce intense thunderstorms that spawn destructive tornadoes.

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Tornadoes - sometimes called twisters - are columns of air that connect a cumulonimbus cloud with the surface of the Earth. One of the most violent of all weather phenomena, tornadoes are very dangerous and can cause massive damage. Tornadoes come in all sorts of sizes and shapes.

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What would you think if you heard Opal, Andrew, Katrina, Hugo, Camille, and Irene were coming to town? Who are they? Long- relatives flying in for a family ?

Not quite! In fact, they're not even people at all. They're past hurricanes! Let's find out how these super storms are born.

Each year, as summer turns to fall, hurricanes begin to appear. These large storms usually occur in the southern Atlantic , Caribbean Sea, Gulf of Mexico, or the eastern Pacific .

Sometimes people think hurricanes are like big tornadoes. They're actually quite different, though.

While a might cover a mile or two of ground, hurricanes are huge storms that can sometimes be as large as 600 miles across. If you look at a map of the United States, you'll see that a hurricane that large would stretch from Philadelphia to Indianapolis!

Tornadoes also usually last no more than a few minutes. Hurricanes, however, can last more than a week because they travel at speeds of only 10 to 20 miles per hour as they cross the .

Hurricanes are defined by their strong winds that can blow from 75 to 200 miles per hour. Before a becomes a hurricane, it starts out as a . storms have wind speeds between 39 and 74 miles per hour.

Even though these storms are not yet hurricanes, they can still cause damage and . Once a 's wind speeds reach or exceed 75 miles per hour, the becomes classified as a hurricane.

Not all storms become hurricanes. Wonder why? The key ingredient to forming a hurricane is warm water.

During the warmer months of hurricane season, the waters in the Atlantic and Gulf of Mexico are the perfect temperature to create hurricanes. As warm, moist air rises from the water into the atmosphere, it creates an area of low pressure underneath.

This causes air from the surrounding areas to flow into the low pressure area. Eventually this air becomes heated and rises into the atmosphere, and the repeats itself.

In this way, hurricanes are kind of like a big engine with a constant supply of and . The "" is the cooler air that keeps the going. The "" is the warm air rising into the atmosphere.

As this continues, clouds and storms form, creating a giant, spinning .

When you look at satellite images of a hurricane, you may notice a hole at the center of the . This hole is called the " eye" of the hurricane.

As the eye passes over land, the weather becomes very calm. Once the eye passes, though, the winds begin again as the second part of the passes over.

Unfortunately, there is no way to stop a hurricane. They do tend to lose strength once they move over land.

Without warm water to continue fueling them, hurricanes will eventually diminish in size and speed until they disappear.

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There's a storm a-comin' today in Wonderopolis. Hang onto your hat!

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We apologize in advance if today's Wonder of the Day is a bit dry!

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When you wake up in the morning and see that it's raining outside, how do you feel? Are you for rain that will help the grass grow and plants ?

Or are you because you will likely get wet on your walk to the bus stop? You might also be that your soccer practice after school might get .

Some people don't mind rainy days, while others wish for sunshine. There's no that we need rain, but many people would like to control how much falls and when.

If it were up to many people, it would only rain in the middle of the night. Plus, it would only rain enough to enough water for plants to and water supplies to .

Unfortunately, we can't control the weather. Sometimes it'll rain all day long and cancel our plans. At other times, it'll rain so much that we might be threatened by floods.

A flood occurs when normally dry land is by water. They're the most common natural disaster, occurring in every state and threatening any part of the world that receives rain. In fact, floods kill more people in the United States each year than lightning, hurricanes, or tornadoes.

Sometimes floods occur slowly over a number of days, weeks, or months, as precipitation levels across hundreds of miles cause river levels to rise slowly. At other times, however, floods can happen in a matter of hours. We call these events flash floods.

Flash floods are defined as floods that occur within six hours of heavy rainfall or another cause. However, flash floods can sometimes happen within minutes or just a few hours of a heavy rain.

Flash floods are particularly because they combine a flood's normal for damage with unpredictability and a time frame. During a flash flood, normally dry creeks and river beds can fill with water and overflow before people have time to .

Heavy rainfall isn't the only cause of a flash flood. Melting snow and ice jams in mountain streams can send torrents of water unexpectedly into low-lying areas. Likewise, dam failures can send walls of water downstream without warning.

Certain areas are prone to flash flooding because of a variety of conditions. For example, areas can be because the construction of buildings, highways, and large parking lots reduces the amount of soil available to absorb heavy rains.

Areas near rivers and large streams are also prone to flash flooding, since heavy rains will naturally find their way to established waterways. Deep canyons and other areas near mountains and steep hills can be deadly when the surrounding topography produces runoff that can flood normally dry areas in a matter of minutes.

Thanks to modern technology, the National Weather Service is able to issue alerts when flash floods may be likely to occur. A flash flood watch indicates that conditions are favorable for a flash flood. A flash flood warning, on the other hand, advises that a flash flood is either imminent or already occurring.

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When you wake up in the morning and see that it's raining outside, how do you feel? Are you for rain that will help the grass grow and plants ? Or are you because you will likely get wet on your walk to the bus stop?

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Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

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What is a Tornado? | How do Tornadoes Form? | Tornadoes

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Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

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Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

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How Hurricanes Form, Hurricane Formation

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Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

# data[].attributes.attachment_link.description
Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

# data[].attributes.attachment_link.description
Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

# data[].attributes.attachment_link.description
Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

# data[].attributes.attachment_link.description
Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

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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.

Last Updated

Aug. 9, 2019

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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. Last Updated Aug. 9, 2019

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As hurricane season approaches, a look back at some of the deadliest storms in U.S. history

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Find out here! Learn the difference between weather and climate, and about the relationship between drought and the earth's water cycle.

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Flood Facts For Kids

Check out our flood facts for kids and learn a range of interesting information about floods.

Did you know that floods can be an important natural process for farming? Understand how floods happen, the different types of flood events and much more with our flood facts for kids.

Depending on their type, floods can develop very slowly over time after extensive rains or in just a few minutes, very quickly, without any sign of rain.

There are many types and ways floods can occur, including, due to overflowing rivers, due to extreme coastal events, by natural or artificial ground saturation from excess rainfall, or by catastrophic failure in infrastructure.

Flash floods are extreme versions of a river flooding event. They can occur very quickly, often without warning and with little or no excessive rainfall. Flash floods are the result of a river blockage either natural or artificial (such as a landslide, glacier, or dam) giving way and releasing a massive amount of built up water.

Areal or urban flooding occurs when low-lying impenetrable ground becomes saturated as rainfall cannot run off as quickly as the accumulation of water. For example, on natural drought hardened or frozen farmland, or on concrete paving.

Floods can damage bridges, roads and other transport links. Infrastructure such as buildings, cars and houses can be left saturated or completely taken by the waters. While sewage systems and power grids can be destroyed.

After floodwaters recede, land can be contaminated with hazardous material, such as building debris, fuel and untreated sewage. Residents are often left without power or clean drinking water which can lead to outbreaks of diseases.

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Flood Facts for Kids - Interesting Information about Floods

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Flood Facts For Kids Check out our flood facts for kids and learn a range of interesting information about floods. Did you know that floods can be an important natural process for farming? Understand how floods happen, the different types of flood events and much more with our flood facts for kids.