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This is a science assignment about Natural Disasters for 2009. This blog will answer the following questions:

-What is a tornado?
-Where do tornadoes come from?
-How fast are tornadoes?
-How powerful are tornadoes?
-How many types of tornadoes are there? What are they?
-What should you do if a tornado comes toward you?
-What is Tornado Alley?

This will also include a bibliography.

By Maggie

What is a tornado?

A tornado is a dark cloud shaped as a funnel and pointed toward the ground. It has powerful, swirling winds and can tear roofs off houses. Tornadoes can smash brick buildings and pick up cars and trucks. A tornado picks up many things, flying wood, glass and other objects. People can become badly injured or killed by the flying objects blowing around in the tornadoes.

Where do tornadoes come from?

Tornadoes come from large thunderstorms. They drop down from the bottom of storm clouds. Although we usually cannot see the wind, tornadoes pick up dust and dirt, making the wind visible.

Tornadoes usually look like dark funnels, coming from the bottom of storms. Some can look like a swinging elephant’s trunk. They can sound like freight trains going by or a waterfall. They cause damage as soon as the bottom of the funnel touches the ground.

How fast are tornadoes?

A tornadoes wind whirls very fast, but can stand still in one place. It usually moves and whips around at speeds from 120 km/h to almost 500 km/h. Tornadoes can move forward at speeds up to 110 km/h.

How powerful are tornadoes?

A scientist, Theodore Fujita made a scale in 1971. The Fujita scale ranked tornadoes by the damage they do, it goes from F0 to F5. The weak tornadoes are ranked as F0 to F1, they usually just damage chimneys and break tree branches. The more powerful tornadoes are ranked F5. They can rip houses from the ground and strip bark off trees. Nowadays, there are many different scales that rank the damage of tornadoes. Some are the Enhanced Fujita Scale and the TORRO scale.

How many types of tornadoes are there? What are they?

There are four types of true tornadoes. There is the multiple vortex tornado, it usually has two or more funnels of clouds rotating around a common centre. A satellite tornado is a smaller, weaker tornado that orbits around a larger and stronger tornado. A water spout is a tornado formed over water, and a land spout is a tornado on land. A land spout is smaller than many other tornadoes, but is quite strong.

The other types of tornadoes are tornado-like circulations. The gustnado is a small, vertical swirl. It is created by the cold, dry outflow of air from thunderstorms. Dust devils are vertical swirling columns of air. It is formed under clear skies and usually in hot areas. They are not as strong as even the weakest tornadoes. A fire whirl is usually formed near large, intense wildfires. Although they are not usually thought of as tornadoes, they can still cause a considerable amount of damage. Steam devils are swirling updrafts that can form near hot springs and deserts. They are very rare, and there also have been some reports of cold air steam devils.

What should you do if a tornado comes toward you?

When a tornado appears, the National Weather Service sends out tornado watches and warnings on television and radio. A tornado watch usually means that tornadoes might form in the next few hours. A tornado warning means a tornado has touched down or someone has seen a funnel cloud. It could also mean that a scientist has seen a tornado on a radar screen.

If there is a tornado nearby, people should find shelter straight away after hearing a tornado warning. If they were available, basements, inside hallways or bathrooms in the middle of the house could be used as shelters. It would be best to stay away from windows, mobile homes and cars because they could be blown away. People should also stay out of auditoriums, gymnasiums, supermarkets and buildings with big roofs because the roof could fall down. If someone was outside, they should lie flat in a ditch and cover their head to protect themselves from flying objects.