Why are tornadoes so dangerous?
Tornadoes—violent, funnel-like storms of strong winds that usually form during thunderstorms—present danger to anyone nearby. These “twisters” can demolish anything in their path, including homes, people, cars, trees, animals, and even entire communities. Sometimes lightweight mobile homes are flipped over. A strong tornado that swept into Xenia, Ohio, on April 3, 1974, leveled a farmhouse and broke everything inside, leaving only three fragile items totally intact: a mirror, a case of eggs, and a box of Christmas ornaments! Occasionally, tornadoes do other strange things—like lifting a 386-ton railway train off its tracks and dropping it 16 feet (5 meters) away!In the United States, an average of 1,000 tornadoes spin up beneath thunderstorms each year. A downward flow of cold air from clouds meets a rising flow of warm air from the ground; if atmospheric conditions are just right, a tornado starts. They occur mainly in a 10-state area known as Tornado Alley, stretching from Texas to Nebraska that also includes Colorado, Iowa, Illinois, Indiana, Missouri, and Arkansas. Most weak tornadoes last less than 10 minutes and travel short distances. Powerful tornadoes have been known to last for hours and a few have traveled more than 100 miles (161 kilometers).