Energy Balance and Circulation Systems

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Energy Balance and Circulation Systems
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Importance

• Energy from Sun (Energy Budget)
• Drives Earths Atmosphere? Creates Circulation
• Circulation Systems
• Create Weather and Climate

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Solar Radiation Entering the Atmosphere

• Absorbed by gases and clouds goes to heating
  (19)
• Scattered and Reflected by Gas Molecules,
  Clouds, Aerosols, and the Earths surface (30)

About 51
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Albedo

• Percent of radiation returning from a surface
  compared to amount of radiation initially
  striking the surface
• Represents the reflectivity of a surface
• Varies depending upon surface
• Earth and atmosphere have a combined albedo of 30

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Albedo
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Earths Energy Balance
Earths overall average equilibrium temperature
changes only slightly from year to year.
A balance exists between incoming solar energy
(shortwave radiation) and outgoing energy from
Earth to space (longwave radiation).
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Energy received at the surface depends on
1) Sun angle with respect to surface. 2) Path of
solar radiation through the atmosphere.
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Same Amount of Energy, Larger Area
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• More direct radiation at Equator than at Poles
• More energy at lower latitudes

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The Energy to Drive the Atmosphere
Unequal distribution in incoming solar radiation
(red) and outgoing Earths radiation (blue)
Atmospheric and ocean circulations redistribute
energy from latitudes with a surplus into
latitudes with a deficit.
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Atmospheric Circulations
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• Rainforests near Equator
• Deserts near 30o North and South

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Atmospheric Circulations
Why the easterlies and westerlies?
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Coriolis Force
An apparent force that is due to the rotation
of the earth.
Winds are deflected to the right in the Northern
Hemisphere. Winds are deflected to the left in
the Southern Hemisphere.
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Coriolis Force Deflection
Greatest deviation at the poles. Zero deviation
at the equator.
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Atmospheric Circulations
Why the easterlies and westerlies?
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Seasonal Changes
January
July
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Ocean circulation
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Without greenhouse gases, the average surface
temperature of the Earth would be 18 C
No greenhouse gases (only permanent gases)
The current atmosphere (with greenhouse gases)
33 C difference
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The other extreme
CO2 rich
CO2 poor
Biotic Atmosphere
Most of the early CO2 is stored as calcium
carbonate (CaCO3) or limestone.
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