Fact 1: Dew is formed when water vapor condenses over night.

Fact 2: If the cooling is sufficient, water vapor condenses into clouds.

Given the two facts above, answer the question "Dew is formed when _ occurs over night" with the following options: 
- cooling
 - imbalanced
 - rain
 - storms
 - warm
 - boiling
 - a solute
 - Joules


 

 cooling        