The bulge at the equator, which Wikipedia says is 42km, means that a point on the equator (at sea level) is 21 km further away from the centre of the earth than the poles. That's two and a half Everests! I think that the difference in the force of gravity (gravity only) between the equator and poles will not be much, and it is gravity alone that keeps the atmosphere here, so why on earth is standing at the equator not like standing at the height of nearly 2.5 Everests?! Am I right in assuming that that very spin which gives the equatorial bulge also ensures that the atmosphere - spinning with the land - is....centrifugally bulged the the equator, too? If so, it almost feels like a happy coincidence.