1. By Eliran Fain- Zilberg, Nave Dagan and Nevo Ben- Naim

2. A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud.

3. Tornadoes are very strong winds that turn around and around and can travel up to 400 kilometers an hour. They can move trees, cars, houses…

4. The strongest and most dangerous tornadoes happen in the U.S.A. Tornadoes are also called cyclones and twisters.

6. The causes tornadoes are: Moisture in the lower to mid-levels of the atmosphere. Unstable air. That is, air that will continue rising once it begins rising from near the ground.

7. A lifting force. Something is needed to cause the air to begin rising. The most common lifting force is heating of air near the ground. As the air warms it becomes lighter and begins rising. Advancing masses of cool air, which force warm air upward, also trigger thunderstorms.

8. The signs of tornadoes are: thunders in the sky, storms…

9. The damage that can tornado bring it: death of many people, destruction of many houses, cars…

10. The states in the U.S.A have the most tornadoes are Nebraska, Kansas, Oklahoma, Texas and Lowa.

12. http://www.youtube.com/watch?v=zjIF5VJhi3Q