Planetary Engineering 1

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Planetary Engineering 1

• Physics of Climate
• Class Exercise

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Zero-Dimensional GEBM
Global energy balance Radiative equilibrium (in
out)
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Goal Planets Temperatures
Important Fact Sun heats less the farther it
is.
Important Factor How does S change with orbit?
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Recall from Topic 1
Change in solar flux sun ? earth
At photosphere surface, solar flux 6.2.107 W-m-2
At Earths orbit, solar flux 1360 W-m-2
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Two Spheres Surrounding Sun
Total energy flux the same through each sphere
R2 2 x R1
R2
R1
The same area at R2 intercepts only 1/4 of
energy it intercepts at R1
? Flux decreases as R-2
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For Earth
Global energy balance Radiative equilibrium (in
out)
Thus, TRAD 255 K
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What about other planets?
How does Trad change with orbit?
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What about other planets?
How does Trad change with orbit?
Planet Distance Albedo Outgoing IR Trad from
sun A.U. W-m2 K Mercury 0.39 0.
06 Venus 0.72 0.76 Earth 1.00 0.30 238 255 M
ars 1.52 0.16 Jupiter 5.20 0.51 Saturn 9.54
0.50 Uranus 19.18 0.66 Neptune 30.06 0.62
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For Mars
Tsurface Trad. How warm can we make its
surface?
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For Mercury
Tsurface Trad. How cool can we make its
surface?
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Venus?
Why cant we adjust Venus the same way?
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End Planetary Engineering 1