Notes
Outline
Lecture 2: Light And Air
Earth’s Climate System
If sunlight strength does not change, how can Earth’s climate change?
Global Energy Cycle
Global Water Cycle
Global Biogeochemistry Cycle
With the same strength of sunlight, changes in the greenhouse effect can result in global temperature change.
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Chemical Weathering
The precipitation process in the atmosphere dissolve and remove CO2 from the atmosphere.
Rocks exposed at Earth’s surface undergo chemical attack from this rain of dilute acid.
This whole process is known as chemical weathering.
The rate of chemical weathering tend to increase as temperature increases.
Weathering requires water as a medium both for the dissolution of minerals and for the transport of the dissolved materials to the ocean
      è The rate of chemical weathering increases as precipitation increases.
Negative Feedback From Chemical Weathering
The chemical weathering works as a negative feedback that moderates long-term climate change.
This negative feedback mechanism links CO2 level in the atmosphere to the temperature and precipitation of the atmosphere.
A warm and moist climate produces stronger chemical weathering to remove CO2 out of the atmosphere è smaller greenhouse effect and colder climate.
Earth, Mars, and Venus
Three Factors To Determine
 Planet Temperature
 Distance from the Sun
 Albedo
 Greenhouse effect
Distance From the Sun
 Solar Luminosity (L)
     the constant flux of energy put out by the sun
                         L = 3.9 x 1026   W
 Solar Flux Density (Sd)
     the amount of solar energy per unit area on a sphere centered at the Sun with a distance d
                         Sd  = L / (4 p d2)   W/m2
Albedo = [Reflected] / [Incoming] Sunlight
Albedo Depends On Color
Albedo of Earth, Mars, and Venus
Global Temperature
Greenhouse Effects
 On Venus è 510°K (very large!!)
 On Earth   è 33°K
 On Mars   è 6°K (very small)
Greenhouse Gases
Why Is It Called “Greenhouse Effect”?
Different Wavelengths of Solar and Earth’s Radiation
Where Does the Solar Energy Go?
Polarward Energy Transport
How Do Atmosphere and Ocean Transport Heat?
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