Coriolis effect

1835 Coriolis effect

The book of science

Tom Sharp

Gaspard-Gustave de Coriolis atmospheric_sciences Coriolis effect

Coriolis effect

The earth moves, the atmosphere has mass, it would all appear as Newton described except for the fact that everything is rotating. Whirl around with a ball at the end of a string and it will seem to pull away from you. This is called the centrifugal effect, which isn’t really a force, but the effect of subtracting the direction of spin from the ball’s inertial trajectory. Similarly, the Coriolis effect makes an object moving on a straight path but in a rotating field of reference appear to swerve against the direction of the spin. * The earth is a spinning sphere so winds and currents appear to veer.


If you stand on the north pole, the earth turns counterclockwise; if you stand on the south pole, it turns clockwise. A great circle between points at the same latitude above the equator arches to the north; but below the equator arches to the south. The Coriolis effect pulls wind and currents to the right when north of the equator and to the left when south.


If I don’t think carefully first, left and right come out at random, it seems, even though I know which direction to turn. But thinking isn’t easy, nor is it easy to remember to think. I often need to think first about needing to.

You tell me why the Coriolis effect pulls to the right in the northern hemisphere but to the left in the southern. I often mix up left and right. A demonstration or animation would be useful.

See also in The book of science:

Readings on wikipedia: