The day is hot and muggy, but cool weather is moving in. All at once, there's a thunderous rumble that sounds like an approaching freight train. The sky darkens and the wind picks up. A spinning cloud touches the ground, tossing roofs, cars, and trees skyward. A tornado is on the move. In Tornado, learn about what causes dangerous swirling storms--from water spouts to violent "twisters." Amazing photographs and a clearly written text explain what happens inside the storm clouds and give you tips about how to stay safe--even if you live in "Tornado Alley.".