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PostPosted: Wed Aug 10, 2011 11:52 pm 
Smeric
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spats wrote:
Torco wrote:
Well, more like -78C° if google is correct. Still, earth reaches those temperatures sometimes, but earth has a less dense atmosphere and less greenhouse effect, so temp shouldn't vary as dramatically on Suenu. Also there's no continents at the poles but there's one pangea that is near the south pole at one latitude. I figure that causes two superficial sea currents along the south coast of the pangea which tend to drag ice from the poles into the ocean. Also, since the rotation is so slow, ocean currents work differently: at the surface the dayside pushes warm water towards the nightside through the poles, and part of that current's bound to go through the poles, in turn warming them. not really warm, but probably enough to melt the eventual dry ice patch that forms... and indeed they form, I'm sure.


It's not so much whether the current setup has landmass at a pole, but rather if it ever did. However, a geologically active planet in the habitable zone with enough gravity to hold onto its volatiles isn't likely to stay in a crashed snowball state forever.

The slow rotation rate actually helps you, for the reasons you brought up. Single-belt rotation or even single-cell (nightside to dayside) circulation is possible in that situation, which allows for a bit better heat distribution across the poles. And you're also right that a little CO2 condensation isn't the end of the world as long as it's more or less in equilibrium with the atmosphere.


yup. Also, I'm toying with the idea of having the planet slowly turn into a snowball over a couple of centuries as to turn it into an apocalyptic conworld, actually CO2 condensation is a good thing.

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PostPosted: Thu Aug 11, 2011 8:10 pm 
Lebom
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vampyre_smiles wrote:
Mashmakhan wrote:
Isn't carbon dioxide supposed to be dangerous to animals when taken in beyond a certain amount? I know that enough of it will give you hallucinagenic effects and a slight burning sensation in your lungs.


spats wrote:
As for the toxicity of CO2, it's not a problem until it's many times the current atmospheric concentration. Current levels are <0.04%; 1% is where some mild effects start; you have to get even higher for it to really start to be dangerous to humans.


I don't remember if this planet was colonized by humans and Earth fauna,

Torco wrote:
1, 2- terrestrial animals transplanted not long ago

That was typed four posts ago...

vampyre_smiles wrote:
but, wouldn't this also be moot if the native species were adapted to deal with the extra CO2?

No. Unless the animal was anaerobic, there is definately a limit to how much CO2 they would be able to take before feeling negative effects.

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Torco wrote:
yup. Also, I'm toying with the idea of having the planet slowly turn into a snowball over a couple of centuries as to turn it into an apocalyptic conworld, actually CO2 condensation is a good thing.

Here is another question: How far away from the habitable zone of Suenu's star is the planet that enough CO2 can freeze to decrease its global greenhouse properties? A little frozen CO2 is nil compared to the amount you would need to keep Suenu warm enough for liquid water to remain permanently on its surface, even if it sits just a little bit outside the habitable zone.

Sorry for being pessimistic but I am facing the same issue with my conworld and CO2 has proven difficult to work with for my purposes. I am wondering how you can manage to make it work for yours.


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PostPosted: Thu Aug 11, 2011 11:42 pm 
Smeric
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Here is another question: How far away from the habitable zone of Suenu's star is the planet that enough CO2 can freeze to decrease its global greenhouse properties? A little frozen CO2 is nil compared to the amount you would need to keep Suenu warm enough for liquid water to remain permanently on its surface, even if it sits just a little bit outside the habitable zone.

It's not really that far away from the habitable zone... I lost the sheet with the exact numbers, and in fact I don't care about them all that much. I've done the maths and it all more or less adds up everytime I do them, but I forget the details... I guess there's an element of authorial fiat in the astronomy, since terms are broadly defined like "yeah, its a dimmer star, the planet gets less irradiation than earth, the mean surface temp is around 5 °C soooo, yeah". I don't care much about the particulars.

yeah, lazy :D

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PostPosted: Fri Aug 12, 2011 7:56 am 
Lebom
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Torco wrote:
Also, I'm toying with the idea of having the planet slowly turn into a snowball over a couple of centuries as to turn it into an apocalyptic conworld, actually CO2 condensation is a good thing.


You can get the snowball effect even without all of your greenhouse gases collapsing. Certainly, it's happened on Earth. And it might be very hard to recover from in this case (also, you have to wonder why it hasn't happened before). I mean, eventually you will recover - the equatorial ice will get dirty and absorb more sun; the oxygen will react out of the atmosphere and be replaced by trace volcanic methane; the star will gradually increase its output etc., but this could take a very, very long time.

On the other hand, you have more favorable air circulation, and the record lows at Earth's south pole only get down to about the freezing point of CO2, so I could imagine that on your planet even in a snowball situation most or all of the surface stays well above the collapse point. If the atmosphere is thicker to begin with (more inert/non-greenhouse gases) then it's even better. You could have a rapid, global glaciation that would be absolutely horrible for the people living there without resorting to, say, eliminating all plant life :)

I mean, there's apocalyptic and then there's apocalyptic, if you know what I mean.


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PostPosted: Fri Aug 12, 2011 10:08 am 
Smeric
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indeed. I'm thinking more of a glaciation where mean equatorial temp over the year gets to around 2°C, so life sucks and then you die, this happening over a period of a few decades, certainly not a long-lasting snowball earth thing, although that is certainly a possibility if a possitive CO2 freezing cycle happens, at least until volcanism breaks under a significant CO2 sink and it all goes back to normal.

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