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Earth is like a huge turntable with the difference that there are no centripetal forces if you are standing still (and the earth is rotating), because earth is slightly flattened towards the equator. So the gravitational forces balance out the centripetal forces, if you are standing still.

But when wind is moving east there is an extra movement in the rotational direction, so there is a force towards the equator. Now, looking from an inertial frame the force is [tex]F_{r}=\frac{mv^{2}}{r}=\frac{mv_{earth}^{2}}{r} + \frac{mv_{wind}^{2}}{r}+\frac{2mv_{earth}v_{wind}}{r}[/tex] The first term cancels to gravity. The second term is the centripetal force and the third term [itex]2mv_{wind}\omega[/itex] is the coriolis force. My problem is: if the coriolis force is constant and the centripetal force obviously is not constant, since the wind's speed in the east west direction changes. How comes winds are moving in circles and not in elipses?