ERTH 1030 Lecture Notes - Wind Speed, Wind Direction, Barometer
5 Feb 2014
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Document Summary
Chapter 5: atmospheric pressure and wind. Atmospheric pressure is pressure exerted by the atmosphere by the force of gravity acting on the overlying column of air. Standard sea level pressure= 101. 325 kpa. Center of a storm with rising warm air will have a pressure <1013 mb. Relies on the atmospheric pressure pushing down on heated mercury in turn measures atmospheric pressure. Air density depends on pressure and temperature. Atm pressure decreases with altitude. So therefore density decreases with altitude. Wind: horizontal movement of air, anometer. Wind direction: the direction from which the wind comes. The west wind comes from the west. Progress from high to low pressure. If this was the only aspect, air would move in a straight line. Isobars: widely spaced! weak gradient and weaker winds. Closely spaced ! strong gradient and strong winds. Unequal heating of the earth surface leads to a pressure gradient and causes wind (surface=latitude, terrain differences, land cover) Forces exerted by ground surface.
