Adapted from Nan'niti et al. 2).

Inertial oscillation is free motion in a rotating system, in other words, it is the motion that a moving object naturally undertakes if it is not acted on by any other external force, and this can be seen everywhere in both the sea and atmosphere. The diagram on the left is the result of tracing the path of a buoy drifting at 30 degrees north latitude2). You can see that it is inertially oscillating while drifting to the bottom left. The cycle of the oscillation of the buoy is one day. As we explained earlier, the cycle of inertial oscillation is a half a day at the poles, but as Coriolis' force decreases at a rate proportional to the sin of the latitude, at 30 degrees north latitude, the inertial cycle is one day.