A tornado is a violently rotating column of air that descends from a cumulonimbus cloud and appears as a funnel. A funnel cloud can be observed before it actually touches the ground and becomes a true tornado. Often, there are sightings of funnel clouds that never reach the ground, therefore they are not really tornadoes.
Tornadoes are, locally, the most destructive of all weather phenomena.
Wind speeds normally range between 100 mph to over 300 mph. They can completely vacuum-up fields, homes, cars and other objects that are in their path. Many have compared the sound of a tornado's winds to a train's or airplane's roar. Tornado's can continue a path of destruction for up to 10 miles or more before dissipating. Tornadoes can strike anytime during the year, but are most common in late spring and early summer.