Today, a landmark was reached in the field of YouTube science. I’m talking, of course, about the collaborative effort by Destin Sandlin of Smarter Every Day and Derek Mueller of Veritasium, to test whether water actually does drain the opposite direction in the Northern and Southern Hemispheres.
It’s a bit of an urban legend that draining water swirls counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. The idea is that the rotation of the Earth imparts a force (called the Coriolis Force) that causes this. Unfortunately, it’s not true. The Coriolis Force is very real, but it’s much too small to have an effect on your sink drain. It’s overwhelmed by other, larger effects like the shape of the basin and the way the water was poured.
However, Destin and Derek ran an experiment to actually observe the Coriolis Force by removing all of these other factors. The result is a pair of videos which are meant to be played simultaneously. If you’ve ever wanted to see the Coriolis Force in action, take a look!