The Coriolis effect is the force that makes wind, water, and virtually every other free-moving thing curve with the rotation of the Earth on its axis. In simpler terms, the constant spin of the Earth to the east makes hurricanes and other large-scale phenomena spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. The key term here is "large-scale phenomena": the force is too weak to affect the flush of a toilet or even the spin of a tornado. In toilets, the shape of the bowl and the force and speed of the water rushing in have a much greater impact on the direction the water spins. And while it's possible that the Coriolis effect could play a role in the direction a tornado spins, that is most often determined by the storm system that spawned it. Still, when all other effects are eliminated -- the water is utterly still, the container is perfectly shaped, and the drain is placed just right -- scientists have actually witnessed the Coriolis effect's impact on a pool of water. We've collected some awesome videos on this topic. Watch them now to learn more.