Tornadoes are the most sudden, unpredictable and violent storms on earth. Tornadoes aren't like hurricanes that are born over open waters and can take days to reach land.

Tornadoes are spawned from thunderstorms that form when warm humid air meets a mass of cool, dry air. Only one in a hundred thunderstorms produces a tornado. They happen quickly and often stay on the ground for only a few minutes.

While Florida gets the most tornados of any state, a strip of land that extends from northeast Texas through Oklahoma, Kansas, Nebraska and Missouri has more tornadoes than any other place in the U.S. That area is called "Tornado Alley."

During the last century, more than 10,000 Americans died in tornadoes. About 1,000 tornadoes are recorded each year in the U.S. -- over 10 times more than in any other country.

Tornadoes can happen in any state, at any time -- on the plains, in cities or forests, early in the morning or late in the evening. They can start in an empty field, or in a busy city, picking up homes, cars and businesses leaving nothing but destruction in their path.