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Earth’s Atmosphere. Blue Planet Lab 102L Fall 2010. Image from http://www.fs.fed.us/rm. nitrogen (N 2 ) oxygen (O 2 ) argon (Ar) trace gases. Atmospheric Composition. major gases. trace gases. from Wikimedia commons. Greenhouse Gases. water (H 2 O) carbon dioxide (CO 2 ) 0.035%
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Earth’s Atmosphere Blue Planet Lab 102L Fall 2010 Image from http://www.fs.fed.us/rm
nitrogen (N2) oxygen (O2) argon (Ar) trace gases Atmospheric Composition major gases trace gases from Wikimedia commons
Greenhouse Gases • water (H2O) • carbon dioxide (CO2) 0.035% • methane (CH4) • ozone (O3) • nitrogen dioxide (NO2) These gases make up a small percentage of all gases present in the atmosphere, but their impacts are immense. Greenhouse gases trap longwave radiation leaving the Earth’s surface, which heats the planet. www.ecy.wa.gov/climatechange
Decreasing decreasing pressure at S.L. 1000 hPa Structure of the Atmosphere
Things to keep in mind… • Air pressure decreases with height above sea level through all of Earth’s atmospheric layers • Temperature decreases with height in the troposphere; may increase or decrease within other atmospheric layers (read lab notes) • Occasionally, temperature inversions occur in the troposphere when cold air is capped by warm air
Radiation and Balance The sun emits short-wave radiation. Some of this radiation is absorbed, and some is re-radiated by the surface, clouds, etc. as long-wave radiation. The reflectivity of a surface is called albedo. grass: 0.20 – 0.25 water: 0.03 – 0.05 cloud: 0.70 – 0.80 snow: 0.80 – 0.85 You can think of this as the fraction of radiation reflected.
How sunlight reaches Earth The angle of incidence affects the amount of heat received at a given latitude. At a higher angle, the heat from the sun is distributed over a greater area, resulting in less energy (W/m2). http://www.bio.miami.edu
San Francisco Omaha Santa Fe Orlando Land – Ocean Contrasts Heat Capacity = energy required to raise the temperature of a unit of mass 1°C The heat capacity of water is 3-4x that of soil. Oceans also transfer heat to depth by mixing, so ocean temperature change is slow. HC of water = 4128 J/kg·K HC of dry air = 1004 J/kg·K What is the annual temperature Change like in different parts of the U.S.?
Seasons Seasons occur because the earth is tilted. Since the Earth is tilted, its path around the sun is associated with different seasons. http://science.howstuffworks.com
Greenhouse Effect vs. Global Warming Do these terms mean the same thing? Greenhouse Effect: The process by which certain atmospheric gases trap long-wave radiation from the Earth’s surface, which causes heating. Global Warming: The observed increase in average temperature of Earth’s atmosphere and ocean in recent decades. Can we infer that global warming is due to an enhanced greenhouse effect? http://www.nahb.org http://news.bbc.co.uk