Question #83ff7

1 Answer
Nov 27, 2017

This happens when water in the cup is cooler than the air.

Explanation:

The amount of water vapor that air can hold is dependent on it's temperature. If you have a cup of cool water, the air immediately adjacent to the cup is going to cool. If it cools to a point where there is more water vapor in the air than it can hold, the extra vapor will condense on the side of the cup.