When water vapour changes directly into ice crystals in the atmosphere without first becoming liquid water, what is this process called?

Correct answer: Deposition or desublimation

The correct answer is B: deposition, also called desublimation. Matter can change between solid, liquid, and gas. In ordinary condensation, a gas becomes a liquid, but in deposition a gas changes directly into a solid without passing through the liquid state. In cold clouds, water vapour can attach to tiny particles and form ice crystals. These crystals may later contribute to snow or other solid precipitation. A is the opposite direction, because evaporation changes liquid into gas. C is melting, in which a solid becomes liquid. D is condensation, but it produces liquid droplets rather than ice crystals. A useful memory cue is that deposition is the reverse of sublimation: sublimation is solid to gas, while deposition is gas to solid.