Temperature
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Topic authorGuest
Temperature
How is the temperature info determined in Celestia? Is it pretty acurate? The reason I ask is that it gives the temperature of Earth as 257 K, which seems a little low. Can one include a temperature line in a planet's definition? Just wondering... Thanks.
If Earth and Venus had no atmosphere, the temperature would be pretty accurate.
Celestia calculates temperature from an object's albedo - it's reflectiveness. A object with a high albedo reflects a lot of light and therefore also reflects heat and is colder than one with a low albedo which absorbs light and heat.
But with Earth and Venus we get a greenhouse effect due to the atmosphere, which means that some of the heat reflected off the Earth is trapped underneath the atmosphere. Celestia doesn't model this "greenhouse effect", and there's no way of defining a temperate in the planet code. So another idea on the wish list, methinks...
Celestia calculates temperature from an object's albedo - it's reflectiveness. A object with a high albedo reflects a lot of light and therefore also reflects heat and is colder than one with a low albedo which absorbs light and heat.
But with Earth and Venus we get a greenhouse effect due to the atmosphere, which means that some of the heat reflected off the Earth is trapped underneath the atmosphere. Celestia doesn't model this "greenhouse effect", and there's no way of defining a temperate in the planet code. So another idea on the wish list, methinks...
"I have been asked, 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question."
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granthutchison
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Perhaps it would be nice to let Celestia work out the appropriate temperature for radiative equilibrium, but to allow the user to insert a "GreenhouseIncrement" in the planet definition. Earth would then have an increment of 20-odd degrees C added to its calculated temperature, Venus several hundred degrees, and Titan (I seem to recall) a negative number, since its atmosphere is more transparent to longer IR wavelengths, and so provides a "negative greenhouse".
It would also mean that our terraformed Mars could be "realistically" warmed in Celestia!
Grant
It would also mean that our terraformed Mars could be "realistically" warmed in Celestia!
Grant