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Unformatted text preview: 1 Solar Radiation- initial source of energy to the Earth. It can be absorbed, reflected and reradiated. The redistribution of this energy controls the structure and dynamics of the Atmosphere and Oceans. Chapter 8 Circulation of the Atmosphere The Atmosphere Is Composed Mainly of Nitrogen, The Atmosphere Is Composed Mainly of Nitrogen, Oxygen, and Water Vapor Oxygen, and Water Vapor What are some properties of the atmosphere? The lower atmosphere is a fairly homogeneous mixture of gases. Water vapor occupies up to 4% of the volume of the atmosphere. The density of air is influenced by temperature and water content. Ascending air cools as it expands. Cooler air can hold less water, so water vapor condenses into tiny droplets - clouds. Descending air warms as it compresses the droplets (clouds) evaporate. Greenhouse Gases Gases: permanent and variable Permanent = present in constant relative % of total volume Variable = concentration changes with time and location Suspended microscopic particles Water droplets The Atmosphere Moves in Response to Uneven The Atmosphere Moves in Response to Uneven Solar Heating and Earth Solar Heating and Earth s Rotation s Rotation An estimate of the heat budget for Earth. On an average day, about half of the solar energy arriving at the upper atmosphere is absorbed at Earths surface. Light (short-wave) energy absorbed at the surface is converted into heat. Heat leaves Earth as infrared (long-wave) radiation. Since input equals output over long periods of time, the heat budget is balanced. Heat budget Solar input must balance solar output Temperature increases/decreases if input is greater/less than output Average Earth Temperature is 16 o C Solar Energy is reradiated from the surface as a long wave. Surface of Earth (including oceans) is heated from above Atmosphere is heated from below 2 O 3 absorbs UV Solar Radiation, heats Atm. Vertical (thermal) structure of the atmosphere Troposphere: lowest layer 0-12 km, temperature decreases with altitude Tropopause: minimum temperature zone between the troposphere and stratosphere Stratosphere: layer above tropopause 12-50 km, temperature increases with altitude Mesosphere: layer above stratosphere 50-90 km, temperature decreases with height Thermosphere: layer above mesosphere >90 km, extends out to space The Atmosphere Density of air depends on temperature, water vapor and altitude Temperature decrease = density increase Water vapor increase = density decrease Altitude increase = density decrease The Solar Heating of Earth Varies with The Solar Heating of Earth Varies with Latitude Latitude How solar energy input varies with latitude....
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- Spring '11