Titan base temp

[Tarran]

If you change anything in Sol, maybe you can add some Sol-specific planet images while you're there.    Those generic blue spheres bug me.

You can change them you know. Bottom line of the F9 screen there should be an option to change a body's image. I'm pretty sure all the planets (but not the Jupiter moons of Europa-Callisto) that are blue spheres have images, excluding Uranus, which is a blue sphere in reality (see wiki page).

[Shoku]

Ummm that's what I said (read my second paragraph again, substitute "infrared" for "long wavelengths" and "colors of light they don't catch" for "short wavelengths"). I'm sure they don't   I'm pretty sure Steve just threw a number in there to get some sort of cutoff. Again, that's what I said.   I guess I should have filled in the dots a little more   And as for not giving off visible light, that depends on the incoming energy flux.   If you put a Dyson sphere a few km above the surface of the sun, it should end up at the surface temperature of the sun because the sun is (I assume) radiating as a black body - the sphere will heat up until it's hot enough to radiate at the same rate (getting rid of the fusion energy). Actually, I'm a physicist - at some point in the distant past of thermo class, they made me derive the black body distribution I also can remember deriving the temperature of the Earth, assuming it's a perfect black body, by balancing incoming solar radiation with outgoing black-body radiation.   The part that amazed me is that it comes out right at ~300K, i. e.  the actual temperature.

John

I was only arguing against the bit about the second law of thermodynamics.
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The greenhouse gases would actually have some different transparency windows (fake term) with the temperature of the planet having a bigger impact on how much heat the greenhouse gas trapped.  Seeing at we're given that little equation instead of potentially having to wait several years for the temperature to rise up to the new equilibrium of the atmosphere it's basically completely clear that it doesn't simulate that.
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I almost didn't see the bit about the Dyson sphere only being a few km from the surface of the sun so I did all this math and was gonna talk about how the regular radius would drop the flux per square meter to 1/500,000th :b

The point of a dyson sphere though would be to "capture" the energy not as heat but most likely as electrical energy.  I guess we could go retro and have hot water turn turbines but I don't think we could get enough water for that by draining the oceans.  No, if we managed any kind of efficiency in that machine it shouldn't get near the temperature of the sun- except if a few km from the sun means the opaque surface and isn't far enough to get any relative vacuum between the two surfaces.
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I put that in more for anyone else reading without the science background.  Maybe I have some kind of obsession with making sure everyone around can follow what I'm talking about.


But really it wouldn't be a violation of the second law of thermodynamics if some planet was getting hotter than the surface of the sun from light emitted by the sun.  Greenhouse gases don't actually give us a heat pump like that.  As long as the entropy in the sun goes up more than the entropy of the planet decreases from catching all this energy then the there's no thermodynamics problem.

[EarthquakeDamage]

You can change them you know. Bottom line of the F9 screen there should be an option to change a body's image. I'm pretty sure all the planets (but not the Jupiter moons of Europa-Callisto) that are blue spheres have images, excluding Uranus, which is a blue sphere in reality (see wiki page).

I already use that option, but IMO letting the end user do it once per campaign (or release, if you have the DB password) is a far less satisfying solution than letting the developer do it precisely once.  It's not very high on my priority list, but I figure it'd be easy to throw in whenever he's tweaking Sol bodies.  Hence the suggestion.

[sloanjh]

But really it wouldn't be a violation of the second law of thermodynamics if some planet was getting hotter than the surface of the sun from light emitted by the sun.  Greenhouse gases don't actually give us a heat pump like that.  As long as the entropy in the sun goes up more than the entropy of the planet decreases from catching all this energy then the there's no thermodynamics problem.

Yes it would.  By definition, temperature is the change in entropy per unit energy (T = dS/dU).  So moving energy from a low-temperature bath to a high-temperature bath in a closed system violates the 2nd law, since you've reduced the total entropy.  This is why air conditioners require an external power source - you need to get the free energy (in the technical sense) from somewhere other than the two heat baths.  One more thing - then entropy of a system goes down (not up) when it emits energy.  Since it has lower energy, there are fewer quantum states available, hence lower entropy (which is the log of the number of quantum states available).

John

PS - You could, of course, make local hot-spots on the surface of the world by running heat pumps, but that's irrelevant for the greenhouse heating discussion.
PPS - Read the Clausius' statement section of the wikipedia article on the 2nd law: http://en.wikipedia.org/wiki/Second_law_of_thermodynamics  That's what I was saying.

[Detjen]

   It seems as though Titan's atmosphere is acting as an anti-green house effect rather than a greenhouse effect as it appears to be programmed into the game.    So since the solar system is manually entered rather than generated as other systems are,  why not just make the base temperature the same and edit the greenhouse gas effect so the temperature reads correct, as that seems to be what the atmosphere is doing in Real life.     if not that way then maybe replacing the atmosphere with Safe Anti-Greenhouse gases to get the desired temp,  and then allow us later explorers to remove those gases and work at building a habitable Titan.

  Though there is one other hole in colonizing titan using the game mechanics.    according to scientific data Titan's gravity is only . 14 not the . 53 as programmed, making the gravity too low for unmodified human colonization.

[Rastaman]

Implement a general effect applicable to any cold atmosphere on any object that has methane in it by ignoring the greenhouse effect of methane in that case.

[Shoku]

   It seems as though Titan's atmosphere is acting as an anti-green house effect rather than a greenhouse effect as it appears to be programmed into the game.     So since the solar system is manually entered rather than generated as other systems are,  why not just make the base temperature the same and edit the greenhouse gas effect so the temperature reads correct, as that seems to be what the atmosphere is doing in Real life.      if not that way then maybe replacing the atmosphere with Safe Anti-Greenhouse gases to get the desired temp,  and then allow us later explorers to remove those gases and work at building a habitable Titan. 

  Though there is one other hole in colonizing titan using the game mechanics.     according to scientific data Titan's gravity is only .  14 not the .  53 as programmed, making the gravity too low for unmodified human colonization. 

If you placed a large parabola of mirrors behind the sun and had it aimed precisely at a planet you could make it MUCH hotter.  The mirror could just sit there stable forever but it could sit still enough to fry the target.

You've misidentified the "closed system" here though.  The surface of the sun is about 6k degrees but the core of the sun is millions and millions of degrees hotter than that.

If you look at the open system of a planet with some star outside the open system (or hey, how about some crazy scenario where it's heated by five of them) then of course there's going to be a huge energy concentration that by all means seems to be giving the planet all kinds of effects that you wouldn't get with increasing entropy.  It looks the same way if your system only contains the surface of the sun and the planet.

But you've got to look at the whole thing when you talk about closed systems.  Refrigerators pump energy from a low temp bath over to a high temp bath all day long but you don't have any problem understanding why that local decrease in entropy isn't a net decrease in entropy if you're really looking at all the energy involved in making that happen.

[sloanjh]

If you placed a large parabola of mirrors behind the sun and had it aimed precisely at a planet you could make it MUCH hotter.  The mirror could just sit there stable forever but it could sit still enough to fry the target.

You've misidentified the "closed system" here though.  The surface of the sun is about 6k degrees but the core of the sun is millions and millions of degrees hotter than that.

If you look at the open system of a planet with some star outside the open system (or hey, how about some crazy scenario where it's heated by five of them) then of course there's going to be a huge energy concentration that by all means seems to be giving the planet all kinds of effects that you wouldn't get with increasing entropy.  It looks the same way if your system only contains the surface of the sun and the planet.

But you've got to look at the whole thing when you talk about closed systems.  Refrigerators pump energy from a low temp bath over to a high temp bath all day long but you don't have any problem understanding why that local decrease in entropy isn't a net decrease in entropy if you're really looking at all the energy involved in making that happen.

I'm going to assume that this was a reply to my message even though it quoted someone else - pesky quote button.

First, I think you meant to put the mirrors behind the earth, with the earth at the focal point, or even a pair of mirrors - one each behind the sun and the earth.  And yes, in this case you could get the earth hotter than the surface of the sun in the limiting case of a big enough sun and a small enough earth (so that the surface areas of the mirrors occupy a negligible solid angle in terms of radiating the energy to empty space).  This is because the temperature of the earth is (mostly) controlled by the question "what is the temperature required to radiate the solar energy it's absorbing back into space as black-body radiation".

  But this isn't what I was talking about.  The original question was "Is there a real-world reason why atmospheric energy retention can only get you so much warming, or is it just a gameplay thing?"  No mirrors involved   My (somewhat tongue-in-cheek) answer was that there are 2nd law reasons why one can't just wave the magic "greenhouse effect" wand and obtain arbitrarily high temperatures.  To put it a different way, if you put a black-body marble in the center of a 1,000 degree (black-body) oven, it will eventually heat up to 1,000 degrees, but it won't get hotter than that (assuming you don't have a source of free energy somewhere that you're using to run a heat pump) - this is Clausius' statement.  Putting greenhouse gasses around the marble isn't going to change that.  And if you cut away 99% of the solid angle of the oven (so that the bit that's left is analogous to the surface of the sun that's emitting at us), you still aren't going to make the marble hotter than 1,000 degrees.  This isn't to say that it's impossible to make the marble hotter than the oven remnant - once you've cut the 99% away it's implied you've got a source of free energy (otherwise the oven remnant would radiate away all its heat and drop in temperature), so you can play all sorts of games like your mirror or lenses to make it hotter.  It's just saying that the greenhouse effect alone isn't going to do it for you.

  I suspect everyone's getting tired of this sub-thread, so I'm going to stop.  I'm happy to continue discussing it with you offline through PMs.

John

[Shadow]

Ultimately, the fact Titan can't be fully terraformed isn't a huge issue. Just reduce the colonization cost as much as possible and put forward a substantial initial investment of infrastructure. The civilian sector will provide bits of the latter as necessary and you won't have to worry about it anymore. In my game, 46 years in, Titan enjoys a healthy population of approximately 800 million. Could be more, but Sol tends to become the primary source of colonists for extrasolar settlements sooner than later.