The South Pole of Mars (Natural Colors; credits: NASA/MGS/MSSS)

Caption NASA:"During Spring, the Ice Cap - predominantly formed by layers of frozen carbon dioxide (dry ice) plus some water ice - begins to shrink as the ices change directly from solid to gas (cosiddetta "sublimazione"). Hazy clouds of ice crystals and fog extend across the bottom of the picture and a darker, more defrosted area, is visible at the upper right, near the Red Planet's night side".