energy balance and circulation systems. 2 of 12 importance energy from sun (energy budget)...

Energy Balance and Circulation Systems

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Importance

• Energy from Sun (Energy Budget)– “Drives” Earth’s 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 Earth’s 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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Earth’s Energy BalanceEarth’s 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

Atmospheric and ocean circulations redistribute energy from latitudes with a surplus into latitudes with a deficit.

Unequal distribution in incoming solar radiation (red) and outgoing Earth’s radiation (blue)

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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 ForceAn “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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