Tornadoes are one of nature's violent storms. Their intense winds can destroy many things such as tossing houses, traffic lights and even uproot trees. In America, tornadoes usually occur in an area called Tornado Alley. The states included in this area are Texas, Oklahoma, Illinois, Missouri, Iowa, Nebraska and Louisiana. Tornadoes are rated on the Fujita Scale from F0-F5 when F0 being the weakest and F5 being the strongest.F0 winds are about 40- 72 mph while F5 tornado winds are about 261- 318 mph. Tornadoes from when warm moist air and cold dry air form clouds. The cumulonimbus clouds shape into a war-head. Before thunderstorms develop, two directions of air coming from opposite directions make a horizontal spinning movement in the cloud itself. Then, when air rises, it creates
an updraft causing the spinning movement to turn into a vertical position. The mesocyclone is formed from the super-cell cloud. Rain and hail begin to fall as the funnel shaped cloud starts to touch the ground. Once successful, the tornado can start its 20 minute journey. However, the minimum for most tornadoes is usually 20 minutes but the maximum is almost an hour. The longest tome for a tornado was the Tri-state Tornado which lasted 3 hours!http://library.thinkquest.org/03oct/01424/how_do_tornadoes_form.htm
