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?
> 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.
> > (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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