Answer:
Desublimation is a phase transition in which a gas changes directly to a solid without passing through an intermediate liquid phase.
It is an exothermic phase change that occurs at temperatures and pressures below a substance’s triple point in its phase diagram.
Desublimation is also called deposition.
Desublimation is caused by a drastic loss in thermal energy from the surrounding gas due to the presence of a much cooler surface.
For example, frost formation occurs on window surfaces during the winter seasons.
This window is at a much cooler temperature, this makes the water vapor in the surrounding air to lose enough thermal energy and change directly into solid which we see as frost during winter.