Tornadoes

Tornadoes

Introduction What can lift roofs from buildings and sweep houses into the air? Tornadoes can! Tornadoes come in many sizes. Some tornadoes are only a few feet (1meter) across. Others are more than a mile (1. 6 km) wide. Some tornadoes touch down for a short time. Others travel for hundreds of miles.

How Tornadoes Form Why do tornadoes happen? Scientists are not sure. Tornadoes come from giant thunderstorms called supercells. A supercell happens when warm, moist air rises to mix with cold, dry air.

The mixing of cold and warm air causes the air to spin. The spinning wind turns into a cloud in a funnel shape. As the cloud turns, the wind becomes stronger. When the funnel cloud touches the ground, it is a tornado.

Measuring Tornadoes Scientists have a way to measure the strength of tornadoes. They look at the harm caused by a tornado. They use the amount of harm to estimate the wind speed. They use a special scale called the EF Scale. The EF Scale measures the strength of the tornado.

Where Tornadoes Form Tornadoes may be hard to measure, but scientists have a good idea where they'll strike. It's true that a tornado can hit anywhere in the world at any time. Most tornadoes happen in the central part of the United States. This area is called Tornado Alley.