A twister, commonly known as a tornado, is a rapidly rotating column of air that extends from a thunderstorm to the ground. Tornadoes form when warm, moist air at the surface meets cooler, dry air aloft, creating instability. This can lead to the development of a supercell, a type of thunderstorm that can produce severe weather, including tornadoes. Tornadoes vary in size, shape, and intensity, with the strongest ones classified as EF5 on the Enhanced Fujita Scale. They can cause significant damage to buildings, uproot trees, and toss vehicles. Tornadoes are most common in the United States, particularly in an area known as "Tornado Alley."