>>As anyone from MN can tell you, even though ice melts at 32deg, it also evaporates at lower temps. Without continued snowfall, eventually it vanishes due to evaporation.
Technically, that is sublimation - a phase change directly from the solid to the gaseous state, with no intermediate liquid state. Evaporation is a phase change of a material from liquid to gaseous.
http://en.wikipedia.org/wiki/Sublimation_%28phase_transition%29#Water
Good catch. Its been 30 years since I tutored Chemistry and now just design microprocessors and it shows. :-)