Myth: Water goes down the plug hole in different directions in the Northern and Southern hemispheres due to the Coriolis effect
01/01/07 00:00 Filed in: Science
Does water always go down the plug
the same way?
Myth
Water in a sink, toilet, bath (etc) rotates counter clockwise in the northern hemisphere and clockwise in the southern hemisphere.
This is due to the Coriolis Effect, which is caused by the rotation of the Earth.
Reality
The Coriolis force is real and is caused by the relative rotation speed of the Earth. That is to say that the Equator runs along at around 1,000 miles an hour, where Madrid in Spain would be 900 miles and hour and the North Pole is stationary.
While this effect DOES exist, it is TINY. Only effecting large objects over long distances. So a projectile fired over many miles will be bent slightly due to the effect. Clearer to the human eye is the way clouds travel from the equator.
Having said all that, the effect on small amounts of water in bath is zero and the twist is due to the pitch of the sink, imperfections and so forth.
As evidence, can I put forward my own bathroom where bath and sink travel in different directions… and before any wag should email me. No, I do not live in Ecuador.
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