1. The problem statement, all variables and given/known data How can ice sublimate at atmospheric pressure? Looking at the p-T diagram for water, the sublimation curve does not extend above a tiny fraction of atmospheric (triple point of water, p = 4.58mm Hg). Yet my ice box tells a different story. 2. Relevant equations p-T diagram for water, available at your local friendly hydrology book store (?). 3. The attempt at a solution I have no clue.