Clouds and Sand on the Horizon of Mars

Joseph E. Smith · Post by **Joseph E. Smith** » Tue Oct 17, 2006 3:26 am

Cool, but it makes me thirsty just looking at it.

SteveShaw · Post by **SteveShaw** » Tue Oct 17, 2006 7:02 am

I see I'm not the only person to take pics with a thumb or lens cap somewhat in the way.

I didn't know Mars had clouds. Wonderful.

Joseph E. Smith · Post by **Joseph E. Smith** » Tue Oct 17, 2006 7:38 am

Though it isn't much of one, Mars does have an atmosphere.

fearfaoin · Post by **fearfaoin** » Tue Oct 17, 2006 7:57 am

Joseph E. Smith wrote:Though it isn't much of one, Mars does have an atmosphere.

Ah, but does it have water?
I figured the clouds were methane or somesuch...

Joseph E. Smith · Post by **Joseph E. Smith** » Tue Oct 17, 2006 8:24 am

It has polar ice caps.

djm · Post by **djm** » Tue Oct 17, 2006 8:44 am

More significantly, Mars does not have camels, so there's no real need to walk a mile.

Overly Smug Ex-smoker

fearfaoin · Post by **fearfaoin** » Tue Oct 17, 2006 9:18 am

Joseph E. Smith wrote:It has polar ice caps.

Fine, I should have said, does it have water vapor?
Maybe so, and that's the part that would have surprised Steve, I bet.

SteveShaw · Post by **SteveShaw** » Tue Oct 17, 2006 9:30 am

fearfaoin wrote:
Joseph E. Smith wrote:It has polar ice caps.
Fine, I should have said, does it have water vapor?
Maybe so, and that's the part that would have surprised Steve, I bet.

You'd need water vapour (which is invisible) in the atmosphere before water-ice clouds were possible. The clouds could I suppose be frozen carbon dioxide, which would require gaseous carbon dioxide to be present in the atmosphere. Water vapour, which is water's gaseous state, can exist in the earth's atmosphere at extremely low temperatures (even liquid water droplets can exist in a supercooled state down to minus 40 degrees). So these things are not surprising - it's just that it never occurred to me!