What is the process called when a gas changes directly into a solid?

The process where a gas changes directly into a solid is known as deposition. This phase transition occurs without passing through the liquid phase and is typically observed in certain conditions, such as when water vapor in the atmosphere forms frost on a cold surface. During deposition, energy is released as the gas molecules lose kinetic energy and arrange themselves into a solid structure. This phenomenon can be seen in nature and is important in various applications, including the formation of ice crystals and the preservation of certain materials.

Condensation refers to the process where a gas turns into a liquid, often observed with water vapor turning into liquid water. Vaporization involves a liquid changing into a gas, and evaporation specifically refers to this process occurring at the surface of a liquid. Neither condensation nor vaporization describes the transition from gas to solid, making them less relevant in this context.