Cyclones spin in opposite directions depending on which hemisphere they are in.

The Coriolis effect is an inertial force first described by French scientist Gaspard-Gustave de Coriolis in 1835. It occurs because different latitudes on Earth rotate at different speeds. While a point on the equator travels at about 1,670 kilometers per hour, points closer to the poles move much slower. This speed difference causes moving air to veer off a straight path relative to the ground.In the Northern Hemisphere, this deflection is always to the right of the direction of travel. As air rushes toward the low-pressure center of a storm, this rightward tug forces the entire system to rotate counterclockwise. Conversely, in the Southern Hemisphere, the deflection is to the left, which forces storms into a clockwise rotation. This fundamental law of physics dictates the behavior of every major hurricane, typhoon, and cyclone on the planet.The strength of the Coriolis force is proportional to the sine of the latitude. At the equator, where the latitude is zero, the Coriolis force effectively vanishes. This is why tropical cyclones almost never form within 5 degrees of the equator and why they cannot cross from one hemisphere to the other. Without the Coriolis force to provide the necessary 'spin,' the low-pressure system simply collapses and dissipates.