Rotating Wall Cloud

Most strong and Violent tornadoes occur with “supercell” thunderstorms. A supercell storm is characterized by rotation within the storm. Typically, this area of rotation occurs in the south side of the storm. Visually, a low-hanging cloud base with rotation is often seen. This area may or may not be visible since rain sometimes wraps around the area of circulation. Rotating wall cloud with very dark sky in background near Lahoma, Oklahoma. (Greg Stumpf)