The process by which water changes from a gas to a liquid is called "condensation." This phase transition occurs when water vapor in the atmosphere cools down, causing the molecules to lose energy and come together to form liquid droplets. Condensation is a vital part of the water cycle, contributing to the formation of clouds, fog, or dew. When warm, moist air rises and cools at higher altitudes, water vapor condenses to create clouds. This process also plays a crucial role in various weather phenomena, and it is fundamental in various applications, including refrigeration and the design of condensation-based humidifiers.