Why do winds rotate counter-clockwise in the northern hemisphere around low pressure?
The reason is that the earth’s rotation sets up an apparent force (called the Coriolis force) that pulls the winds to the right in the northern hemisphere (and to the left in the southern hemisphere). So, when a low pressure starts to form north of the equator, the surface winds will flow inward, trying to fill in the low, and will be deflected to the right and a counter-clockwise rotation will be initiated. The opposite (a deflection to the left and a clockwise rotation) will occur south of the equator.
