How does the Coriolis effect work?
The Coriolis effect describes apparent deflection of moving objects in a rotating reference frame. It matters for large-scale winds and ocean currents on Earth. It is not an independent energy source that starts the motion.
Latitude and motion direction
In Earth's frame, horizontal motion tends to deflect right in the Northern Hemisphere and left in the Southern Hemisphere. The horizontal effect varies with latitude and vanishes at the equator. Its magnitude depends on speed and planetary rotation. Actual airflow also requires pressure gradients, friction, and curved-path dynamics. Right and left are defined relative to the direction of motion.
Large and small scales
The effect is important for weather systems, long-range motion, and ocean circulation. It does not reliably determine which way a household sink drains, where basin shape, initial flow, and drain design dominate. Precision experiments differ from everyday observations. Assessment requires the event's length and time scales as well as latitude; other forces can dominate short, small-scale processes.