Water that exists in a gaseous state is called water vapor. Water vapor normally forms from liquid water through a process called evaporation, but it may also form directly from ice through sublimation.
When water vapor cools, it undergoes a process of condensation through which small droplets of water are formed. If these droplets maintain their small dimensions, they remain suspended in the air, forming clouds or fog. If the droplets become larger, they create precipitation in the form of rain, snow or sleet, depending on the temperature. In nature, water transforms from one state of matter to another and moves between the atmosphere, the ground and underground areas, creating the hydrologic cycle, as indicated by the Arkansas Geological Survey.