Condensation

Condensation is the change of the physical state of matter from gas phase into liquid phase, and is the reverse of evaporation. 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.

Initiation

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.

Reversibility scenarios

A few distinct reversibility scenarios emerge here with respect to the nature of the surface.