Does it snow CO2 at Earth's poles?

[Findthepin1]

I was thinking about Mars' polar CO2 ice and it occurred to me that since CO2 freezes at like -56 Celsius, shouldn't Earth have these environments, at least temporarily? I see no reason why not, in the winter parts of inland Greenland, Siberia (probably) and Antarctica go below that temperature.

[SargeRho]

If there was enough CO2 in the atmosphere, yes, it would sometimes snow CO2 at the south pole, and I would guess that in 2010, when it got to -94.7°C, quite a bit of CO2 did indeed freeze out.

[Exploro]

No. According to this blog on the topic there just isn't enough CO2 in the atmosphere to have the vapor pressure necessary to transform from gas to solid on Earth even when polar temperatures can easily drop below the temperature for such a phase change to occur at 1 Atmosphere.

[magnemoe]

7 hours ago, Findthepin1 said:

I was thinking about Mars' polar CO2 ice and it occurred to me that since CO2 freezes at like -56 Celsius, shouldn't Earth have these environments, at least temporarily? I see no reason why not, in the winter parts of inland Greenland, Siberia (probably) and Antarctica go below that temperature.

56, I thought it was -120 celsius. This might be an showstopper on exoplanets who are relies on lots of co2 to keep them warm as they are technical out of the goldilock zone. 

[fredinno]

33 minutes ago, magnemoe said:

56, I thought it was -120 celsius. This might be an showstopper on exoplanets who are relies on lots of co2 to keep them warm as they are technical out of the goldilock zone. 

Hmm, well, a water-heavy, or water lacking planet might be able to get away with it, as water vapor is a GHG (benefiting the former) and lack of water can also stop cooling since ices have a higher albedo- lack of ice means more radiation ends up absorbed.

33 minutes ago, magnemoe said:

56, I thought it was -120 celsius. This might be an showstopper on exoplanets who are relies on lots of co2 to keep them warm as they are technical out of the goldilock zone. 

Hmm, well, a water-heavy, or water lacking planet might be able to get away with it, as water vapor is a GHG (benefiting the former) and lack of water can also stop cooling since ices have a higher albedo- lack of ice means more radiation ends up absorbed.

[Findthepin1]

Oops, it's -78 Celsius. Whatever, still possible, that has still been surpassed fairly commonly. My question still stands. And has been answered. 

Edited February 28, 2016 by Findthepin1

[PB666]

3 hours ago, Findthepin1 said:

Oops, it's -78 Celsius. Whatever, still possible, that has still been surpassed fairly commonly. My question still stands. And has been answered. 

Actually, This was the reason CO2 levels in that atmosphere were not rising like scientist believed they would back in the 60s and 70s. CO2 particularly likes very cold precipitation, the fog that forms over the arctic ocean and then falls has been really good at pulling CO2 from the air, the oceans then picked this up and transported it down into the deep ocean, but now its started to come back to the surface. But its not dry ice by any means, its just CO2 rich regular ice.

[lajoswinkler]

If there was more of it in the atmosphere, it would deposit itself, but there is not. For something to precipitate, its partial pressure in the fluid needs to be equal to the vapor pressure of the precipitate. At that point, the precipitate and the vapor are in dynamic equilibrium - rate of particle liberation is equal to the rate of particle deposition/condensation. Any change of temperature or pressure in favor of the precipitate will cause it to, well, precipitate completely (faster if the conditions are further away from the point of equilibrium).

 

Partial pressure of carbon(IV) oxide in air is 0.04 * 101325 Pa = 4.052 Pa. It's way too low. That's why a block of dry ice, even if you put it out when it's almost -90 °C on Antarctica, will be gone one day.

Same thing with water ice on Ceres. It can not exist in vacuum at Cererian temperatures.