system
Given the following post, respond as if you're commenting on Reddit:
human
How is water able to stay in gaseous form in air (water vapour) well below its condensing temperature?
gpt
All liquids have what's called a vapor pressure. Essentially, if you leave the liquid sitting open to air it evaporates, often very slowly, until there's a certain concentration (partial pressure) of it in the air. The vapor pressure also depends on temperature, which is why hot air can be more humid than cold air.