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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.)

Mark
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  • related https://earthscience.stackexchange.com/questions/18895/are-ice-ages-affected-by-the-freezing-out-of-co2-in-antarctica – trond hansen Mar 21 '24 at 06:48
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    Does this answer your question? Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica? – David Hammen Mar 21 '24 at 13:18
  • The TL;DR answer to your question is no, at least for the last billion or so years. – David Hammen Mar 21 '24 at 13:19
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    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. – David Hammen Mar 22 '24 at 12:22
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    I made the above a comment as opposed to an answer because the duplicate question has answers that contain this information. – David Hammen Mar 22 '24 at 12:27

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