The pressure gradient force causes air to move from higher pressures toward lower pressures....?

Question

The pressure gradient force causes air to move from higher pressures toward lower pressures (perpendicular to the isobars), yet actual winds rarely blow in this fashion. Explain why they don’t.

Answer 1

There are the additional effects of solar heating and earth's rotation. Heating tends to drive a general motion of air away from equatorial regions toward the poles and more locally, vertical convective movement. Meanwhile earth's rotation and resulting Coriolis effect cause rotation of the air masses moving poleward (clockwise in the southern hemisphere and counterclockwise in the northern hemisphere.) The result is that most low-pressure regions contain rotating air masses which mean tangential motion as well as inward radial motion.

Answer 2

The Coriolis effect is one of the main reasons. It deflects the winds to the right in the northern hemisphere and to the left in the southern hemisphere. S in the NH the winds generally go anticlockwise around a low pressure system, with a slight inward component and for highs they go in a clockwise direction with a slight outward component. The amount of influence the Coriolis effect has depends on the latitude. Near the equator it is small, so isobars do not work well near there.
Surface friction also causes large variations to the wind flow.

Answer 3

This ought to be helpful:

http://en.wikipedia.org/wiki/Geostrophic_wind