CO2 in Antarctica

[Jovial Monk]

It does get cold enough in Antarctica to freeze CO2.

Anyone know where in Antarctica temperatures get that low?

Does CO2 actually freeze in Antarctica?

[Bobby]

It does get cold enough in Antarctica to freeze CO2.

Anyone know where in Antarctica temperatures get that low?

Does CO2 actually freeze in Antarctica?

Yes it does freeze CO2 in Antarctica.

The freezing point of carbon dioxide is -78.5 oC.
Occasionally this low is exceeded in Antarctica, and small quantities of CO2 are frozen out,
but are returned soon after to the atmosphere.


Does CO2 solidify in Antarctica?
-57 C is the boiling point of CO2. The freezing point of CO2 at atmospheric pressure is -78.5 C (-109.3 F).
If the temperature reaches -113 F at Vostok, Antarctica, some carbon dioxide might freeze out of the air,
assuming that the carbon dioxide vapor pressure drops to its saturation vapor pressure

[Jovial Monk]

The top of the Antarctic plateau in Eastern Antarctica gets cold enough to freeze CO2. However, the partial pressure of CO2 is too low there to actually freeze.

[Bobby]

The top of the Antarctic plateau in Eastern Antarctica gets cold enough to freeze CO2.
However, the partial pressure of CO2 is too low there to actually freeze.

Its' not quite cold enough to form a thick permanent layer.
It does on the poles of Mars.

[Jovial Monk]

It is the very low partial pressure of CO2 at the extreme altitude of the Antarctic Plateau stops it from freezing.

[Super Nova]

It is the very low partial pressure of CO2 at the extreme altitude of the Antarctic Plateau stops it from freezing.

I had to look up what you mean.

https://stevengoddard.wordpress.com/201 ... reeze-co2/

Antarctica Gets Cold Enough To Freeze CO2
Posted on June 3, 2014 by stevengoddard
Last year, Antarctica reached -135ºF, which is 27ºF below the freezing point of CO2 at atmospheric pressure. This is cold enough to freeze CO2 right out of the air.

There has been some long standing confusion about this because we do not find dry ice in Antarctica, except in their ice-cream machine.

There are different concepts which people confuse related to the partial pressure of a gas. Consider water vapor. Temperatures can drop below freezing, without frost accumulating on your windshield. This is because the number of molecules sublimating is equal to the number of molecules freezing. Until the temperature drops below the dew point or frost point, ice will not accumulate. The dew point/frost point is a function of the partial pressure of water, which is also a function of the humidity. The humidity has almost no effect on the freezing point.

Put in simple terms, ice does not accumulate at temperatures above its dew/frost point, because it is evaporating just as fast as it is freezing. When the temperature drops below the dew/frost point, more molecules are freezing than are sublimating.

The same thing is true with CO2. At 0.0004 mole fraction of the atmosphere, CO2 has a very low partial pressure, so it won’t accumulate at -135ºF. That doesn’t mean that CO2 molecules aren’t freezing – it simply means that they are sublimating at the same rate as they are freezing, so there is no net buildup.

Partial pressure is a statistical measure which has no meaning to the behavior of any individual molecule. It does affect the numbers of molecules which are freezing. It doesn’t affect the freezing point.

[Jovial Monk]

Some molecules freeze only to sublimate again. With a higher partial pressure more frozen molecules remain frozen.