What phenomenon occurs when water vapor in the air transforms back into liquid?

The correct answer is condensation. This process occurs when water vapor in the air cools down and transitions back into liquid water. This can happen when warm, moist air rises and encounters cooler temperatures, leading to the condensation of water vapor into tiny water droplets. These droplets can cluster together to form clouds, fog, or dew.

In the context of the water cycle, condensation is a crucial stage that facilitates the formation of precipitation. It is essential for understanding weather patterns, as it often precedes rain or snow. In contrast, the processes of evaporation and infiltration pertain to different aspects of the water cycle. Evaporation describes the transition of liquid water into vapor, while infiltration involves water soaking into the ground. Each of these processes plays a vital role in the overall dynamics of water movement in the environment, but only condensation specifically addresses the change back to the liquid state.