May 21, 2012 - Happy Birthday, Gaspard-Gustave de Coriolis

The forces of weather creates winds that blow in a straight direction.

But if you've ever studied weather, you've probably seen that wind doesn't always blow straight—winds tend to veer off in curving paths as they travel over the Earth's surface.

For example, huge storms called hurricanes (or cyclones or typhoons) famously rotate like giant pinwheels around the eye—the calm center of the storm.

Why is that? 

A man named Coriolis first described the physics of energy in rotating systems. We call the "force" that causes air and water to travel in curving paths, because of the rotation of the Earth, the Coriolis effect.

Born in Paris, France, in 1792, Coriolis is one of 72 names of scientists and engineers engraved on the Eiffel Tower in the late 1800s. The engraved names are painted in gold.

Contrary to popular belief....

The Coriolis effect has nothing to do with the direction of water swirling down the drain in sinks and toilets. It only works on very large scales, such as planetary atmospheres and oceans. Still, many people will tell you that water in toilets and sinks swirls counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere, due to this force.

It just isn't so.

The direction that the water swirls has to do with the shape of the sink or toilet bowl, and also of course the way that the water enters the bowl. Maybe you can start observing all the sinks and toilets you have access to and see if they all empty with swirls of water in the same or different directions.

Learn more about the Coriolis force.
The Little Shop of Physics even has a suggested activity that should help explain what the force is all about. 

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