<P> Condensation is the change of the physical state of matter from gas phase into liquid phase, and is the reverse of vapourisation . The word most often refers to the water cycle . It can also be defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere . When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition . </P> <P> Condensation is initiated by the formation of atomic / molecular clusters of that species within its gaseous volume--like rain drop or snow flake formation within clouds--or at the contact between such gaseous phase and a liquid or solid surface . </P>

Water droplets that condense from the air onto cool surfaces are called