Detailed Instructions: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
Q: Air contains invisible moisture called water vapor. Excess water vapor is condensed out as water in the form of water droplets. Water droplets are carried up into the clouds. The clouds become heavy with water droplets. When the cloud is saturated. Rain will fall. 
A:
water vapor ,water droplets ,cloud ,rain 