14 - Varying albedos that exist on Earth’s surface...

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Standard unit : Millibar (mb) Mean Sea Level pressure exerted at the surface = 1013 mb (standard sea-level pressure This allows us to compare pressures at different locations, taking into account differences in elevation. Values are important because they provide the cutoff measurements used to define low and high pressure cells. Low pressure (aka Cyclone) Area where the pressure is lower than standard sea-level Air is rising upward away from the surface relieving pressure from that surface. High pressure (aka anticyclone) Area where pressure is high. Air descends toward the surface, barometers rise indicating an increased atmospheric pressure on the surface. Differences in Pressure Thermally induced changes in air pressure are related to temperature differences that result from: * Unequal distribution of insolation * Differential heating of land and water
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Unformatted text preview: * Varying albedos that exist on Earth’s surface. Daytime heating: Warms the surface Air expands in volume and decreases in density As density decreases, air will rise and lower the atmospheric pressure at the surface Thermally induced rising of warm air contributes to the low pressures that dominate the equatorial regions If air becomes cold: There will be an increase in density and a decrease in volume This causes the air to sink thus increasing the atmospheric pressure Polar regions regularly experience high pressure. Horizontal Differences in Pressure The difference between the highest and lowest sea level pressures over North America on a given day might amount to only 25 mb. Although horizontal differences in pressure can generate violent winds, these differences are small compared to vertical differences....
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This note was uploaded on 06/12/2011 for the course GEOGRAPHY 600-201010 taught by Professor Christopherpost during the Spring '10 term at Kent State.

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