A tornado is a violently rotating column or air in contact with the ground. When the column of air is not in contact with the ground, it is called a funnel cloud. A tornado in contact with a water surface is called a water spout. Tornadoes can vary greatly in size, intensity and appearance. Wind speeds in a tornado can range from just less that 100 miles per hour to over 200 miles per hour. The intensity of a tornado is classified using the Fujita scale.