On Dec 9, 2008, at 12:40 PM, Don Mannino wrote: > read that on Mars, the air is very cold and totally dry, and when > there is exposed ice the water evaporates directly, and is lost into > space because the air cannot hold it I don't know about the escaping into space part, but otherwise what is happening is "freeze-drying," where water goes directly from solid into a vaporous state, especially when exposed to near vacuum (very low air pressure). The lower the total air pressure, the more water vapor pressure can and will "want" to "take up the void" (in my attempt to put things learned in high school chemistry into more colloquial English - probably fracturing the science a bit in the attempt). The "air" on Mars is near vacuum (not just "dry"). Something similar happens to our snowpack on our mountains here: it shrinks due to directly evaporating into the air, much of it never actually melting and becoming liquid. Regards, Fred Sturm University of New Mexico fssturm at unm.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut_ptg.org/attachments/20081209/d6634e4c/attachment.html>
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