The effect is absent at the equator and increases as you move toward the poles. The third force affecting the direction of wind is that of friction . The inspiral at a low-pressure center is counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. The outspiral at a high-pressure center is clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. Air moves out of these high pressure areas toward the equator creating the trade winds .
Winds also move toward the midlatitudes creating the w esterlies .
The monsoon is a seasonally reversing wind pattern that brings heavy rains onto the Asian subcontinent in summer and hot, dry conditions in the winter. Winds at an altitude of 5 to 7 km above the earth's surface are influenced by pressure gradient force and Coriolis force but not by the force of friction. These are the geostrophic winds that flow parallel to isobars. Rossby waves are large undulations in the flow of the upper air Westerlies along the zone of contact between cold and warm air. They allow warm air to penetrate northward and cold air to penetrate southward.