The Coriolis effect is an effect that derives from the Coriolis force.

Assuming there is an object of mass, standing on a spinning surface and trying to reach from one point of the surface to another point, and therefore have axial velocity – cannot go in a straight direction – instead it moves in curve, this phenomenon explained by Coriolis force.

The effect can be seen in our daily life, for example: the way of the currents around the world derive from the Coriolis force that cause by the spinning of Earth, same with the wind directions. Those examples can be explained easily thanks to this video:

Now to the question: assuming that there are two friends, sitting on a carrousel that spins clockwise from both sides, one of them holding a ball and want to deliver it to the other friend.

In which direction shall that friend throw the ball?

Hint: watch this video -