Global Warming on the Moon?
Posted by Jeff Id on December 6, 2009
We’ll in my recent post on why some fraction of global warming is absolutely real, I made the comment that if people wanted to see whether the blackbody equations presented by Lucia hold up reasonably well to a no-atmosphere planet in earth levels of sunlight they could simply look at the moon. There has been a bit of discussion on it so I did the work myself.
First I had to find the lunar albedo it turns out that the value is 0.078. I had no idea the moon was dark material, blogging is fun when you learn stuff like that. Link for the data is here.
So using the amazingly simple approximations by Lucia, I plugged in the same values of solar energy as earth. After all the moon is closer to the sun and farther from the sun exactly half of the time. I calculate an average temperature of 273K (according to the above).
The average day temperature and average night temperature are given at this link. It’s in degrees C so we need to add
is 273+107 = 380K in the day and 273-153 = 120K at night for a net average of 250K. This is 23C cooler than a simple calculation would demonstrate and if the same result was made on a planet with an atmosphere we would give have the impression that there was 23 C created by greenhouse gasses. However, the lunar surface has a great deal more variance in temperature than the earth which creates substantially more error in the simple calculation.
If someone is interested in working the math to take into account non-linearity of temperature distributions, it would make an interesting post. It’s Sunday though, and I think some fun is in order.