What Is the Coriolis Effect?

Named after French mathematician Gaspard-Gustave de Coriolis (1835), this effect arises because Earth surface moves at different speeds at different latitudes — about 1,670 km/h at the equator but zero at the poles. An object moving northward from the equator carries its faster eastward momentum into regions that rotate more slowly, causing it to veer east (appearing to curve right in the Northern Hemisphere). The Coriolis effect is crucial for large-scale atmospheric circulation: it turns winds around pressure systems, creating the cyclonic rotation of hurricanes (counterclockwise in the north, clockwise in the south) and driving the trade winds and jet streams. The effect is proportional to the object speed and the sine of latitude, so it is negligible for small-scale phenomena — the "bathtub drain" myth (that water spirals differently in each hemisphere) is false for ordinary sinks and toilets.