The process by which water vapor cools and changes into liquid water is called condensation. This phenomenon occurs when warm, moist air rises and cools, resulting in the water vapor losing energy and changing back into its liquid form. Condensation plays a critical role in various natural processes, such as the formation of clouds and precipitation. It is also observed on surfaces, like when dew forms on grass during cool nights. This fundamental principle helps maintain the water cycle, contributing to ecosystems and weather patterns.