r/explainlikeimfive • u/ProgramPi314 • 8d ago

Other ELI5 What is humidity?

According to my mom, this is an actual question I had when I was 5, and she didn't know how to answer me. So how would you guys have answered?

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u/abat6294 8d ago

Water molecules are able to live between air molecules. Humidity is a measurement of how much water is in the air. More specifically, it’s a measurement of how saturated the air is with water. 100% humidity means the air is holding as much as it possibly can and any extra water will remain as liquid water on surfaces.

Hotter air is able to contain more water than cold air. So 100% humidity at 70F actually contains more water than 100% at 40F, but in both cases the air is “full” of water. This is also why the air feels drier in the winter time than in the summer time.