The coldest temperature ever measured at Vostok Station is -89.2 °C, well below the sea-level sublimation point of carbon dioxide at -78.5 °C. However, Vostok Station is well above sea level (3488 m). Is this still cold enough to get natural dry ice, or is there some other location with a combination of temperature and altitude that can form dry ice? (Plateau Station, for example, is slightly higher and is suspected to be even colder.)
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$\begingroup$ related earthscience.stackexchange.com/questions/18895/… $\endgroup$– trond hansenCommented Mar 21 at 6:48
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3$\begingroup$ Does this answer your question? Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica? $\endgroup$– David HammenCommented Mar 21 at 13:18
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$\begingroup$ The TL;DR answer to your question is no, at least for the last billion or so years. $\endgroup$– David HammenCommented Mar 21 at 13:19
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1$\begingroup$ The claimed sea level sublimation point of -78.5°C assumes pure carbon dioxide at 1 atmosphere of pressure. This is a valid assumption for a block of dry ice as a thin layer of pure $\text{CO}_2$ forms around the sublimating block. The temperature at which $\text{CO}_2$ undergoes deposition (deposition is the flip side of sublimation) depends solely on the partial pressure of carbon dioxide, which currently is a bit above 40 pascals. It would have to get to -140°C for $\text{CO}_2$ to undergo deposition at sea level, and even colder at altitude. The Earth does not get that cold. $\endgroup$– David HammenCommented Mar 22 at 12:22
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1$\begingroup$ I made the above a comment as opposed to an answer because the duplicate question has answers that contain this information. $\endgroup$– David HammenCommented Mar 22 at 12:27
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This answer, citing Reference [1], reports the existence of carbon dioxide and some other volatile compounds frozen into water-ice clathrates on sea bottoms; actually methane is the most common guest in such naturally occurring clathrates. Both availability of the volatile guest and solubility (or rather, lack thereof) in the liquid phase play a role in the predominance of methane water-ice clathrates on Earth's sea bottoms.
Direct freezing of pure carbon dioxide into the solid phase on Earth is less likely (my nice way of saying definitely not). Wikipedia's data indicate that at the quoted temperature of -89.2°C the vapor pressure of solid carbon dioxide is over 100 mm Hg, whereas even at sea level the partial pressure of carbon dioxide in our atmosphere is (still) under 1 mm Hg. (The sublimation temperature given in the question is under pure carbon dioxide, not under Earth's atmosphere.) The difficulty of obtaining solid carbon dioxide under natural conditions is illustrated by the fact that even on the more hospitable planet Mars, the solid is available only seasonally around either pole.
Reference
- W. P. Dillon, in Robert A. Meyers, Encyclopedia of Physical Science and Technology, Third Edition (2001).
