Question

Process in which water vapor turns directly to a solid

Answer 1

This process is known as deposition and is the opposite of sublimation, hence why it is sometimes called desublimation

Answer 2

The reverse of deposition is sublimation and hence sometimes deposition is called desublimation. 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 causes the water vapor to change directly into a solid.