Deposition

Deposition is a process in which gas transforms into solid without going through the liquid state. The reverse of deposition is sublimation. One example of deposition is the process by which, in sub-freezing air, water vapor changes directly to ice without first becoming a liquid. This is how snow forms in clouds, as well as frost and hoar frost on the ground. Another example of physical deposition is the artificial process of physical vapor deposition, used to deposit thin films of various materials onto various surfaces.