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! Using her praised combination of clear text and detailed illustrations, Gail Gibbons explains how tornadoes form, the scale used for classifying them, and the safest places to go in case one should happen near you.