The idea that water swirls down a drain in a different direction in the Southern Hemisphere smacks a bit of this fanciful notion, but it is in fact based on a scientific principle known as the Coriolis effect. The Coriolis effect is not a force; it is a consequence of the Earth’s rotation that causes large-scale atmospheric events, like mid-latitude cyclones and hurricanes, to rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.