system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why did my wet towel dry in the freezer after it was frozen?

I've been freezing a wet towel to make smoking outside more bearable. And after it was frozen solid I left it in the freezer for a few days and it dried. Umm how? Where did the ice go?
gpt
It sublimed! Many freezers are kept at a slight vacuum to make them easier to keep cold. But that vacuum is lower than the vapor pressure of water, so ice can turn directly into vapor. There is still no where for the water to actually go though. So if you look around you'll find it attached to the freezer walls or ceiling as ice again.