Coriolis effect

The picture at the top shows an inert frame of reference, where the black object moves in a straight line. In the picture at the bottom the observer(red dot) sees the object follow a curved path, because of the Coriolis and Centrifugal effects

This storm over Iceland spins counter-clockwise due to balance between the Coriolis force and the pressure gradient force.

The Coriolis effect is a force that is found in a rotating object. Gaspard Gustave de Coriolis first described the Coriolis effect in 1835 using mathematics. The Coriolis effect can best be seen in hurricanes. In the Northern Hemisphere, they spin counter-clockwise (because the earth spins counter-clockwise), and in the Southern Hemisphere they spin clockwise.

One example of the Coriolis effect that is often described is that water flows down a drain in the opposite direction in the northern and southern hemispheres. However, in reality, the force of the Coriolis effect is not strong enough to see in such a small amount of water.