Reply 117 - absolutely the dust devils are proof of hot surface cooler atmosphere and we have seen a lot of those!
There is a lot of Water Ice on Mars and it is in certain places melting perhaps way beneath the surface but it is there.
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A water cycle does exist the poles come and go something is rising up each season to create new caps granted CO2 is falling and freezing also. Hopefully Pheonix will shed more light on this soon.