Suction vortices, also known as suction spots, are substructures found in many tornadoes, though they are not always easily visible. These vortices typically occur at the base of the tornado, where it makes contact with the ground. Sub-vortices tend to form after vortex breakdown reaches the surface, resulting from the interaction of cyclonically incoming and rising air. Although multi-vortex structures are common in tornadoes, they are not unique to them and can occur in other circulations, such as dust devils. This is a natural result of vortex dynamics in physics. Multi-vortex tornadoes should not be confused with cyclically tornadic
supercells. Supercells are large, rotating thunderstorms that can produce multiple, distinct tornadoes, often referred to as
tornado families. These tornadoes may form at different times or exist simultaneously but are separate from one another. A phenomenon similar to multiple vortices is the
satellite tornado. Unlike the multiple-vortex tornado, where smaller vortices form inside the main tornado, a satellite tornado develops outside the main tornado's circulation. It forms through a different mechanism, typically as a result of interactions with the parent storm's environment. Despite appearing close to the primary tornado, satellite tornadoes are independent and can have their own rotation. In rare instances, multi-vortex tornadoes may display their strength through the uncommon method of "horizontal vortices", in which tornadoes appearing to "bend" their multiple interior vortices; this results in a tornado appearing to radiate thin lines. Examples of tornadoes featuring horizontal vortices include the
2011 Tuscaloosa-Birmingham EF4 and
1999 Bridge Creek-Moore F5 tornadoes. == Types of Multi-Vortex Tornadoes ==