A tornado is really a small cyclone. It can be up to a mile in diameter, and can cause terrible damage. Tornadoes occur when the conditions to create ordinary thunderstorms are extremely violent, which happens very rarely and only in certain parts of the world. There is an updraft of air, around which winds blow in opposite directions. This starts a whirling effect, and a narrow spout is formed. Air is thrown away from the spout, leaving an area of low pressure in the center of the tornado, which act like a very powerful vacumm, sucking up almost everything in its path. The winds around the tornado are also very destructive they can reach speeds of up to three hundred miles an hour.