Tornadoes - It's a violent windstorms that form a vortex. In the U.S. there are about 770 every year, most of the tornadoes occur from April through June and they form along with severe thunderstorms. The Fujita scale measures the strength of all tornadoes and this comes after tornadoes.
Hurricane Formation - This formation must have warm water temperatures that create warm/moist air. It has five steps and the first one is it begins as a bunch of thunderstorms. Second step is warm air from the storms moves to the center and rises creating clouds. Third steps is clouds form a ring, which is also a eye wall. Forth step is the ring spins and grows, the final step is the storm dies once and it goes far into the land.