The Martian polar caps : is the ice present the result of snow falls or frost buildup? I read that the northern PC is about 25’thick-this would argue that the cap is made up of snow.
have we ever observed a snowstorm on Mars?
Without Googling, I thought they were methane.
And after Googling, I see they’re CO2.
The northern cap is water and is impressively layered indicating not all of it sublimates. http://spacefellowship.com/news/art13446/radar-map-of-buried-mars-layers-matches-climate-cycles.html
Meanwhile at the south pole you do apparently get "snow’
from http://www.nasa.gov/mission_pages/MRO/news/mro20120911.html#.Uq8WAPRDuSo