Ch Winds

Low air pressure at the equator, due to the constant rising of heated air. Low air pressure at the equator, due to the constant rising of heated air. Cold heavy air at the poles sinks, causing high pressure regions. Cold heavy air at the poles sinks, causing high pressure regions. Pressure differences create worldwide air movement (winds)…air moves from high pressure to low pressure. Pressure differences create worldwide air movement (winds)…air moves from high pressure to low pressure.

Global Winds The Coriolis force causes winds to be deflected to the right in the N. Hemisphere, and to the left in the S. Hemisphere. Greatest effect at the poles. The Coriolis force causes winds to be deflected to the right in the N. Hemisphere, and to the left in the S. Hemisphere. Greatest effect at the poles. Warm air rising at the equator spreads poleward in both directions. Warm air rising at the equator spreads poleward in both directions. Some sinks at 30 degrees latitude, forming high pressure zones with air flowing away both north and south. Some sinks at 30 degrees latitude, forming high pressure zones with air flowing away both north and south.

At 60 degrees latitude, surface air from the polar highs meets the air flowing from the 30 degree highs. At 60 degrees latitude, surface air from the polar highs meets the air flowing from the 30 degree highs. Converging air rises, forming low pressure areas at 60 degrees latitude. Converging air rises, forming low pressure areas at 60 degrees latitude. The three looping patterns of flow in each hemisphere are called convection cells. The three looping patterns of flow in each hemisphere are called convection cells.

Look up and define: trade winds, doldrums, horse latitudes, westerlies, polar easterlies Look up and define: trade winds, doldrums, horse latitudes, westerlies, polar easterlies

Wind and Pressure Shifts Yearly seasonal cycles mean that the global wind belts shift about 10 degrees of latitude during the course of a year. Yearly seasonal cycles mean that the global wind belts shift about 10 degrees of latitude during the course of a year.

Local Winds Breezes—gentle winds that extend less than 100 km. Breezes—gentle winds that extend less than 100 km. Often caused by local conditions that produce temperature differences. Often caused by local conditions that produce temperature differences.

Land and Sea Breezes Land heats up faster than water when both receive equal sunlight. Land heats up faster than water when both receive equal sunlight. During daylight, warmed air above land rises, creating low pressure. During daylight, warmed air above land rises, creating low pressure. Cooler air from over the water moves in to replace it…a sea breeze. Cooler air from over the water moves in to replace it…a sea breeze. At night, the reverse occurs, the land cools faster, and a land breeze develops. At night, the reverse occurs, the land cools faster, and a land breeze develops.

Mountain and Valley Breezes During daytime, warmed air in valleys moves up mountain slopes…a valley breeze. During daytime, warmed air in valleys moves up mountain slopes…a valley breeze. At night, in the quickly cooling mountains, cold mountain air flows downhill into the valleys, a mountain breeze. At night, in the quickly cooling mountains, cold mountain air flows downhill into the valleys, a mountain breeze.