Coriolis

Suppose that you were on a massive sphere (hint: you are) and that that sphere were rotating about a singular axis (hint: it is) and that you could in fact get aboard some strange variety of vehicular device which could move above the surface and seperate to it at a rate equal to the linear velocity of that particular patch of surface given the rotation speed (hint: you can). If you were to point in the direction that the patch of land directly underneath you is going and hold that vehicle in the same position, moving at the same speed as the patch of land underneath you, that patch of land would in fact MOVE.

Because the shortest distance between two points on a sphere is not in fact a straight line but a curve (hint: use string and a globe) you will by holding the attitude of the craft travel in that curved line. If going eastward in the northern hemisphere, you would curve towards the southwards, or more simply, you will always curve away from the pole who dominates your hemisphere. Meaning, you will approach the equator and given limitless fuel for your vehicular device, make a darn big sinusoidal wave of sorts.

Which means of course, that being as how you have moved, that land hasn't actually moved. It continued on it's circular path and your circular path took on new incredible dimensions - particularly, the third dimension!

All this has been made possible by the sick breeding of vector calculus, conic sections and geometric algebra. Woo math!

TRH