Earth's Atmosphere

1
Earth's Atmosphere (CH 1, pp.3-19)
99 of atmospheric gases, including water vapor,
extend only 30 kilometer (km) above earth's
surface. - Most of our weather, however,
occurs within the first 10 to 15 km.
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Composition of the Atmosphere

• A mixture of many gases
• Composition is not constant

Fairly stable gases
Nitrogen Oxygen Argon
Variable Components
Water Vapor Aerosols Ozone Carbon Dioxide
3
Atmospheric Composition
Other Gasses 7
Other Gasses 1
Ar 93
Methane Ozone Nitrous Oxides Aerosols Water vapor

Nitrogen and Oxygen are the two most abundant
gasses in the atmosphere
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Water Vapor
Clouds are made when water vapor in the air
turns into liquid This process releases Latent
Heat
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Aerosols
Small solid particles and liquid droplets in the
air (excluding cloud Droplets and precipitation).
Ex. Haze over the Himalayas The Asian Brown
Cloud
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Aerosols
Dust off the coast of Morocco
Other examples include Pollen Sea
salt Pollution Smoke ash
From MODIS
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Ozone Formation in the Stratosphere
O2 UV-C ? O O O O2 M ? O3 M
Protects the Earth from Harmful Ultraviolet
rays From the sun.
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Atmospheric Vertical Structure
Pressure Density
-The number of air Molecules decrease with
height, therefore Density (mass/volume) and
Pressure (force/area) decrease with height
-Standard Atmospheric Pressure 1013.25mb or
29.92 in Hg.
Figure 1.7
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Atmospheric Layers
300 km

• 4 layers are defined by trends in average air
  temperature
• Molecules in the thermosphere have extremely high
  temperatures
• Mesosphere cools with height
• -Stratosphere warms due to ozone (O3) absorption
  of high energy solar radiation
• - Troposphere cools with height because the
  Earth is warm from solar heating

Figure 1.9 p.16
Temperature Inversion where temperature
increases with height
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Atmospheric Mixture and Charge

• Additional layers include
• Layers defined by mixing of gasses
• The homosphere evenly mixed atmospheric gasses
• b) The poorly-mixed
  heterosphere
• AND
• Electrically charged portion of the atmosphere
  called the ionosphere

Figure 1.10