Which process involves water vapor turning directly into ice?

The process that involves water vapor turning directly into ice is sublimation. This occurs when water vapor transitions to a solid state without first becoming a liquid. Sublimation can be observed in various environments, such as when frost forms on surfaces during cold weather. In this case, water vapor in the air directly crystallizes into ice, bypassing the liquid phase altogether.

In contrast, condensation refers to the process where water vapor changes into liquid water, typically forming droplets upon cooling. Freezing is the transition of liquid water to ice, which requires the water to first exist in a liquid state. Evaporation is the process where liquid water turns into water vapor, the opposite of what occurs in sublimation. Understanding these definitions clarifies why sublimation is the correct choice for this question.