Book excerpt: What in the world is a tornado? In this age of extreme weather, this newly updated edition of Gail Gibbons' informative introduction to tornadoes, with safety tips included, answers that question. Tornadoes form when hot, humid air rises from the ground and meets with the cooler, denser air that is falling back to Earth. The two airstreams begin to swirl, pulling in more and more air to form a funnel-shaped cloud. The winds can swirl faster than 261 miles per hour! Newly revised and vetted by weather experts from National Oceanic and Atmospheric Association, Tornadoes is an accessible introduction to this fascinating phenomenon. Using her praised combination of clear text and detailed illustrations, Gail Gibbons shares more than fifty tornado facts. . . . including how tornadoes form, the scale used for classifying them, and the safest places to go in case one should happen near you. Featuring simple, kid-friendly text, colorful paintings, and well-labeled diagrams, Gail Gibbons' nonfiction titles have been called ""staples of any collection" (Kirkus Reviews) and offer clear, accessible introductions to complex topics for young readers beginning to explore the world.