Welcome Hmmm

Yep, fog can form on Mars, it can also form within your back yard. All that's required is for the temperature to drop below the 'dew point' of the the ambient atmosphere. On Mars the partial pressure of the water vapour is so low that the water form can only be ice. Microscopic crystals held in a 'colloidal' suspension apear as freezing fog. Even then it would be fairly tenuous and a very chilly temperature of ~-150C

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