On Feb 21, 9:27 am, Crown-Horned Snorkack <chornedsnork...@[EMAIL PROTECTED]
>
wrote:
> On 21 veebr, 00:51, Logan Kearsley <chronosur...@[EMAIL PROTECTED]
> wrote:
>
> > On Feb 20, 9:27 am, Crown-Horned Snorkack <chornedsnork...@[EMAIL PROTECTED]
>
> > wrote:
>
> > > On 20 veebr, 09:17, Logan Kearsley <chronosur...@[EMAIL PROTECTED]
> wrote:
>
> > > > On Feb 19, 11:12 pm, Bryan Derksen <bryan.derk...@[EMAIL PROTECTED]
> wrote:
>
> > > > > Logan Kearsley wrote:
> > > > > > On Feb 18, 6:12 pm, Bryan Derksen <bryan.derk...@[EMAIL PROTECTED]
>
wrote:
> > > > > >> If it is cold enough for CO2 to start freezing out on the
antistellar
> > > > > >> pole, then the atmosphere is already demonstrably not capable
of
> > > > > >> sufficient heat transport thaw frozen CO2 back there.
>
> > > > > > It's demonstrably not capable of sufficient heat transport to
thaw
> > > > > > frozen CO2 given not-necessarily-permanent current conditions.
That
> > > > > > doesn't mean it can't warm up again.
>
> > > > > No, but with CO2 absent from the atmosphere you'll have to warm
it up
> > > > > again via some mechanism other than greenhouse effect.
>
> > > > Well, obviously.
>
> > > Why? Why not greenhouse gases other than carbon dioxide?
>
> > > Like methane? Boiling point lower than that of carbon dioxide.
>
> > > Imagine... over time, methane concentration in atmosphere slowly
> > > increases, the general temperature rises... till the dark side gets
> > > warm enough to evaporate the carbon dioxide. Runaway greenhouse
effect
> > > follows - first the carbon dioxide evaporates, then ice seats and
> > > oceans thaw.
>
> > Because they're not likely to be very common. If you start out with
> > lots of methane, the conditions for collapse will be much colder but
> > you probably won't accumulate very much CO2 (it will tend to be
> > destroyed in the reducing environment), and if you start out with lots
> > of CO2, the planet probably doesn't contain much methane (because it
> > will tend to be destroyed in the oxidizing environment), or suitable
> > stuff to make methane out of, barring biological activity.
>
> Are carbon dioxide and methane stable when they are together in mildly
> reducing conditions?
Don't know. Possibly, but someone more knowledgeable is free to
correct me on that.
> > Might be worth thinking about some other possibilities, though. Maybe
> > nitrous oxide could work in some special cases- if there's a thin
> > nitrogen atmosphere and high UV flux to break up water ice and let
> > hydrogen escape, you could eventually accumulate free oxygen which
> > would combine with the already-present nitrogen.
>
> Do you mean NO or N2O?
>
> N2O condenses as easily as CO2.
True. Ought to have checked up on that. And NO2 seems to condense even
easier still.
I suppose I actually mean NO, then. Which probably means that the
total atmospheric pressure would continue to drop precipitously as
N2O, NO2, etc. get removed, unless enough NO can be built up to
reverse the process before the nitrogen runs out.
> > > (The cycle has a return side, too: once the oceans are open,
> > > photosynthetic production increases. Small quantities of free oxygen
> > > are released into atmosphere and the surface layer of ocean, while
> > > deep ocean remains anoxic and dead organic matter sediments there.
The
> > > free oxygen rapidly removes the methane from atmosphere...)
>
> > -l.
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