Supercells are like the king of the skies, but shaped like an anvil. They are the main reason why tornadoes form. Suppercell thunderstorms have two sides, cloudy and sunny, and a hard rain/hail side. Quite literally good cop and bad cop. Anyways, supercells have a roating updraft whiich is called a mesocyclone. This is the main rotation that is caused by warm moist air colliding with dry cool air. then theres down drafts like the rear flank downdraft, and the front flank down draft that create a rotating wall cloud or shelf cloud. However, the shelf cloud is rare and is part of the outer edge of a storm. If you see a supercell in the sky, dont worry, most supercells do not form tornadoes.