| Planetary
radiative equilibrium |
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| Energy absorbed = Energy radiated |
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| \ | (L/(4d2))r2 = 4r2T4 |
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| \ | T = 278 (L/d2AU)1/4 K |
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| • | Greenhouse effect : |
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| Earth’s atmosphere relatively
transparent to solar |
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| radiation
(heating) |
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| but
re-radiation (cooling) in infrared is impeded |
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| (photons
absorbed by CO2, H2O) |
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| • | For Venus,
greenhouse effect is enormous |
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| due to
CO2, T = 600K (could
happen at Earth) |
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