What is Rotation?

Rotation is the process by which an object, air mass, or weather system moves around a central axis. In meteorology, rotation plays a crucial role in the development of severe weather, including tornadoes and hurricanes.

In the atmosphere, rotation can occur due to wind shear, which is the change in wind speed or direction at different altitudes. When strong wind shear is present, it can create horizontal rolling motions in the air. If a thunderstorm updraft tilts this horizontal rotation into a vertical position, it can lead to the development of a mesocyclone, a key precursor to tornado formation.

Rotation is also a fundamental characteristic of hurricanes and low-pressure systems, where air moves in a circular pattern around the storm’s center. The Coriolis effect, caused by Earth’s rotation, influences the direction of these rotating systems—counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

Understanding rotation is essential for storm prediction and safety. Meteorologists use radar to detect rotating air masses and identify potential tornadoes before they touch down. Homeowners in tornado-prone areas can benefit from this knowledge by having a tornado shelter or safe room ready when rotating storms approach.