Tornadoes

Tornadoes are violent windstorms that can develop inside thunderstorms when warm, moist air meets cold, dry air. A tornado forms when the warm air rises above the cold and twists into a funnel-shaped cloud. This is why tornadoes are sometimes called twisters.

Funnel clouds can drop out of thunderstorms with little or no warning. These snake-like clouds extend down and sometimes touch the ground. When they do touch down, they can cause damage.

Tornado funnels act like big vacuum cleaners. Tornadoes pick up dirt, trees, buildings and everything else that their violent winds destroy.

Tornado wind speeds can reach 300 miles per hour. No other winds blow that fast. The winds are so powerful that they can drive a piece of straw right through a board.

The Fujita Scale relates wind speed to how much damage a tornado causes. Using this scale, tornadoes are classified from F-0 to F-5. The higher the number, the more severe the tornado.

Tornadoes occur all over the world, but most of them happen in the United States. Of the U.S. tornadoes, most of them happen in an area called Tornado Alley. The flat lands of Texas, Oklahoma, Kansas, Nebraska, Iowa and Missouri have many tornadoes each year. Other states have tornadoes, too.

Tornado season begins in spring and lasts through summer. The states in Tornado Alley can see 50 or more tornadoes a week during tornado season. Some of these tornadoes are big, but most are small.

Many people watch for tornadoes during tornado season. Meteorologists, scientists who study weather, watch weather radar for possible tornadoes. Radar is a device that tracks storms and weather.

Spotters are people who are sent out to different areas when conditions are right for tornadoes. The spotters watch the clouds carefully and report any funnel clouds they see.

When conditions are right for tornadoes to form, the National Weather Service will issu0e a tornado watch. If meteorologists see tornadoes on radar and spotters see the tornadoes, a tornado warning will be issued. Sirens will sound in the towns in danger.

When the siren sounds, people in the affected areas should take cover immediately. In a house, people can go to their basements, storm cellars or closets. People should stay away from outside walls and windows. Tornado winds can collapse walls and shatter windows.

People caught outdoors or in cars should head for the nearest building or find a ditch and cover their heads with their hands. Tornadoes don't travel in a predictable path and easily can toss cars through the air.

At a school, students take shelter in basements or inner halls and cover their heads. Most schools in Tornado Alley states have tornado drills for students. Teachers show students what to do and where to go if a tornado happens while they are at school.

Along with violent winds, tornadoes also have dangerous lightning and hail. During a tornado, people shouldn't use their phones because lightning can travel along phone wires and hurt them.

Each year severe tornadoes hit places in the United States. These tornadoes cause damage, injuries and death. Flying debris causes most tornado-related injuries and deaths.