The word "tornado" comes from the Latin tonare, meaning "to thunder." The Spanish developed the word into tornear, to turn or twist. These are good descriptions of tornadoes, which are formed by rotating or twisting air. This is why they are also called twisters or cyclones.
A tornado is a powerful column of winds spiraling around a center of low atmospheric pressure. It looks like a large black funnel hanging down from a storm cloud. The narrow end will move over the earth, whipping back and forth like a tail.
The winds inside a tornado spiral upward and inward with a lot of speed and power. It crates an internal vacuum that then sucks up anything it passes over. When the funnel touches a structure, the fierce winds have the ability to tear it apart.
The winds inside a twister can spin around at speeds up to 500 miles an hour, but usually travels at roughly 300 miles an hour. This makes the tornado the most dangerous storm known to mankind. Because of the earth’s unique weather system, twisters rotate counterclockwise in the Northern Hemisphere and move eastward. They rotate clockwise in the Southern Hemisphere. Tornadoes also often come with hailstorms.
Many storms create harmless funnels that never touch earth. They can last from a few seconds to a few hours. Others disappear and reappear minutes later. The average tornado has a diameter of about 200 to 300 yards, and some grow large enough to spawn smaller tornadoes known as satellite tornadoes. These small offspring, about 50 yards across, can be very fierce and do lots of damage. They also tend to branch away from the parent funnel, taking separate paths across the earth.
A tornado can form very quickly, sometimes in a minute or less. It can travel across the ground at high speeds, then just as suddenly vanish. They can kill in a matter of seconds. Every year, about $500 million worth in damage is done by twisters in the United States. Most tornadoes last less than twenty minutes and travel less than 15 miles. However, superstorms sometimes occur, traveling over 100 miles before they are exhausted. Although they don’t occur very often, they are responsible for 20% of all tornado casualties.
