What is the tendency of Earth's rotation to turn winds called?

The tendency of Earth’s rotation to turn moving winds is called the Coriolis effect. It does not create wind by itself; instead, it deflects air that is already moving across Earth’s rotating surface.

Because Earth rotates eastward, the apparent deflection is to the right of motion in the Northern Hemisphere and to the left in the Southern Hemisphere. The effect is zero at the equator and becomes stronger toward the poles. Its influence also increases when air moves faster or travels over a longer distance.

The Coriolis effect helps organize large-scale weather systems. In the Northern Hemisphere, hurricanes and other low-pressure systems rotate counterclockwise, while high-pressure systems rotate clockwise. The opposite pattern occurs south of the equator. Jet streams and broad ocean currents are also shaped by this planetary effect.

A common misconception is that the Coriolis effect determines which way water drains from a sink or toilet. At that small scale, local factors such as the container’s shape, residual motion, and the drain design overwhelm the effect. The rotation matters most for large, long-lasting systems such as storms and atmospheric circulation.