A tornado is a violently rotating column of air extending from the base of a thunderstorm down to the ground. Tornado intensities are classified on the Fujita Scale with ratings between F0 (weakest) to F5 (strongest). They are capable of completely destroying well-made structures, uprooting trees and hurling objects through the air like deadly missiles. Learn how to prepare for a tornado, what actions to take when the warning is issued and after the tornado has passed.