An F1 tornado in central Oklahoma

A tornado is a tube of violently spinning air that touches the ground. Wind inside the tornado spins fast, but the actual ‘circle’ of wind around them is huge. This makes tornadoes very dangerous. Tornadoes are especially dangerous to people in cars or mobile homes and about 60 people are killed by tornadoes every year.

Tornadoes mostly happen during strong thunderstorms called super cell storms. They cause a lot of damage to anything in their path. Tornadoes are ranked on the Fujita scale, from F0 to F5. The F0 has the lowest wind speed, and the F5 has the highest one.

Tornadoes can happen in nearly any part of the world. In the United States, a tornado has happened in all states. The middle part of the United States is nicknamed ‘Tornado Alley’ for the number of tornadoes there. A tornado can have wind speeds of over 300 miles per hour (480 km/h). Most tornadoes have wind speeds less than 110 miles per hour (180 km/h), are about 250 feet (80 m) across and travel a few miles before disappearing.

Sometimes, tornadoes happen in groups. 148 tornadoes struck on the same day in April 1974. Many towns in the midwestern United States and Canada were destroyed. More than 300 people died. They were hit by flying wrecks, buried under houses, and thrown by powerful winds. That day, students in Xenia, Ohio were practicing for a play on the auditorium stage. One girl looked out the window and saw the tornado. The students ran into the hall, covering their heads. A few seconds later, all the school buses flew right onto the stage.

A man in another town hid under the couch in his living room. He held onto one couch leg. The tornado struck his house, and winds blew around him. When the tornado left, he was outside. There was no house. The couch had disappeared, and he was only holding onto one couch leg.

Tornado watches/warnings/emergencies

A “tornado watch” is given when the weather conditions look like a tornado could form. A ‘PDS (Particularly Dangerous Situation)’ watch is given when a likely tornado outbreak is to start, many strong tornadoes will form in the area, or an ongoing tornado outbreak is in the works in the area. A “tornado warning” is given if somebody has actually seen a tornado or if a tornado ‘signature’ (usually the storm has a ‘hook’ or ‘U’ echo) has shown up on radar. Tornado emergencies are issued in Special Weather Statements or Tornado Warnings saying that a powerful tornado is about to hit an area with a lot of people in it (especially cities in Tornado Alley), a tornado has been spotted, and the tornado is expected to cause deaths.

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  F4 Tornado in Roanoke, Illinois on July 13, 2004

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