Clouds: 
A visible form of condensed water and/or ice particles in the atmosphere suspended above the earth's surface in the atmosphere. In addition, clouds may include solid particles such as those present in fumes, smoke, and dust. 

Condensation:  
The physical process where a gas changes into a liquid; in this case, when water vapor changes into water. 

Condensation Nuclei: 
A term for smoke, dust, or any other small particles in the air used in clouds by condensed water. 

Evaporation: 
The process where a liquid changes into a gas; in this case, when water changes into water vapor. 

Water Vapor: 
A colorless, odorless gas in the atmosphere created when water goes through evaporation.