What force helps hurricanes rotate because Earth spins?

The force that helps hurricanes rotate because Earth spins is the Coriolis force.

The Coriolis force is an apparent force observed in Earth’s rotating reference frame. It deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. Around a low-pressure center, that deflection helps organize winds into the spiraling circulation associated with a hurricane.

A tropical disturbance still needs warm ocean water, moisture, and a pre-existing area of rotation to develop. The Coriolis force helps provide the turning motion, but it is not the hurricane’s energy source. Hurricanes generally do not form directly at the equator because the Coriolis effect is too weak there; most develop several degrees of latitude away.

The force is named after French mathematician Gaspard-Gustave de Coriolis, whose 1835 work described the mathematics of motion in rotating systems. It is sometimes called the Coriolis effect, although “force” is the more precise term in this context. Its influence is important over the large distances and long timescales of weather systems, not ordinary small-scale motion.