Prevailing westerlies carry weather eastward across the northern United States and southern Canada. The polar easterlies blow somewhat from east to west in two belts between the poles and about 60 north and south latitude. Surface air moving away from the poles moves westward across faster-moving points nearer the equator. Synoptic-scale circulations are air motions around relatively small regions of high and low pressure in the atmosphere. These regions form within the larger general circulation.
Air flows toward low-pressure regions called lows or cyclones.
Air flows away from high-pressure regions called highs or anticyclones. Viewed from above, the wind moves clockwise around a high and counterclockwise around a low in the Northern Hemisphere. These directions are reversed in the Southern Hemisphere. Highs and lows generally move with the prevailing winds. As they pass a given spot on the earth, the wind direction changes.