What would happen to the surface temperature of the Earth if Earth had the Moon's lack of an atmosphere? My initial knee-jerk response was as follows:
the Earth would have drastic temperature swings like the Moon.
According to the Artemis Project data, the moon and earth's temperatures compare as follows:
Minimum surface temperature of Earth: -89 degrees C.
Maximum surface temperature of Earth: 58 degrees C.
Temperature spread of Earth: 147 degrees C.
Minimum surface temperature of the Moon: -147 degrees C.
Maximum surface temperature of the Moon: 100 degrees C.
Temperature spread of the Moon: 247 degrees C.
As you can see, the Moon has a much greater spread between high and low temperatures. The ratio of the Earth's temperature spread to the Moon's is .595, rounded off to .60.
But then it occurred to me that the Earth's surface area is mostly water and the Moon's surface area is mostly basalt. Question: How much does the presence of water verses basalt affect the surface temperature of the Earth?
Time to do some math:
Water has a specific heat capacity of 4.1813 J/g*deg. C and its mass is 18 g per mole. Basalt's specific heat capacity is .84 J/g*deg. C and its mass is 54 grams per mole.
Q = cm(T)
c is the specific heat coefficient, m is mass, T is the change in temperature, Q is the amount of energy needed to affect the temperature change.
Assuming that the Earth and Moon receive about the same amount of solar energy, it makes sense to use the same value for Q when comparing basalt and water.
Water: 100J = (4.1813)(18g)( T)
T(water) = 1.33 deg. C.
Basalt: 100J = (.84)(54g)(T)
T(basalt) = 2.2 deg. C.
Conversely, if the water and basalt were allowed to cool, and lost 100 J, their temperatures would decrease -1.33 deg. C and -2.2 deg., respectively.
Now, what do you suppose happens when I divide 1.32 deg. C by 2.2 deg. C?
I get .60--the same ratio as the Earth/Moon temperature spreads. Now that's interesting!
When solar energy is added or removed, water increases and decreases nearly the same rate as the Earth, and basalt's temperature increases and decreases at nearly the same rate as the Moon.
The implication here is that if the Earth lost its atmosphere, its surface temperature would not change much. It appears to be the oceans, not the atmosphere which have the greatest impact on the Earth's surface temperatures.
Your thoughts?