Visitor Submit by Willis Eschenbach
Some time in the past, I wrote a put up referred to as “The Moon Is A Chilly Mistress”. In that put up I mentioned how the typical temperature just isn’t correct when there are enormous swings in temperature. Or to be clearer, I mentioned why the typical temperature of the moon is far decrease than you’d count on given the space from the solar. Learn the put up for the total dialogue. Right here’s the cash graph from that put up.
Sadly, the one knowledge that I had for that put up was the temperature from the Apollo mission. I nonetheless didn’t have a superb measure of the temperature of the whole lunar floor.
Wanting round, I discovered a examine referred to as “The worldwide floor temperatures of the Moon as measured by the Diviner Lunar Radiometer Experiment“, which contained the next graphic of lunar floor temperature. This exhibits temperature across the moon at a single second in time.
Authentic Caption: International instantaneous temperatures of the Moon in (a) cylindrical equidistant projection (ϕss = 180°) and (b) orthographic projection (ϕss = 180°, 120°, and zero°).
Sadly, nowhere within the graphic or the article itself did it say what the typical temperature of the moon is. So … I needed to take a great distance round.
The great distance appears like this. I took the graphic of the moon temperatures and the graphic of the temperature scale. And after extra experimentation than it ought to have taken, I used to be in a position to make use of the size to assign a temperature to every pixel within the graphic. What I did was to match the purple, inexperienced, and blue values of the colour of every pixel to the colour scale, work out which colour within the scale it was nearest to, and convert it to the corresponding temperature. What we used to name a “SMOP”, a “small matter of programming”, which is at all times a much bigger matter than you’d like.
On the finish of all that enjoyable, I checked my outcomes by printing them up on my traditional globe, the Mollweide projection.
Works for me …
As soon as I’d transformed it to temperature, I then transformed every gridcell to the equal Stefan-Boltzmann radiation and averaged these. This gave me a median outgoing radiation of some 303.5 W/m2.
And this let me verify the accuracy of my figures. The lunar albedo is usually considered on the order of 11-12%. The outcomes I’ve give an albedo of 10.7% … I’d name that affirmation.
Lastly, to match my outcomes to these in my earlier put up, I’ve:
Earlier Submit This Submit
Temperature by Direct Common -77°C -75°C
Temperature by Radiation Common -2.5C -2.7°C
Conclusion? Effectively, finally, I’ve some actual numbers for the lunar temperature. And so they affirm that the Stefan-Boltzmann equation does a superb job of estimating the lunar temperature, whether or not we do it by averaging radiation and changing to temperature, or whether or not we common the temperature straight.
And which of the 2 methods of averaging temperature is right? Effectively, each, or neither. You should utilize both one, relying in your wants. The underlying downside is that you could’t common an “intensive” variable like temperature … however that’s a dialogue for one more day.
Right here, as a result of we’re simply previous the total moon the forest is alive at evening, and our cat needs to go outdoors irrespective of the hour. Nevertheless, there are coyotes, raccoons, badgers, foxes, and the occasional mountain lion on the market, so he has to remain inside at evening. Ah nicely, within the morning I’ll must let him out. Can’t use a “doggie door”, the raccoons love these, so … they are saying canines have homeowners, however cats have a workers, and I can solely agree.
Better of the evening to all,
NOTE: As is my customized, I ask that to stop misunderstandings, once you remark please quote the precise phrases that you’re discussing.