Water that condenses from water vapor in the atmosphere and falls to Earth as separate drops from clouds. Rain forms primarily in three ways: at weather fronts, when the water vapor in the warmer mass of air cools and condenses; along mountain ranges, when a warm mass of air is forced to rise over a mountain and its water vapor cools and condenses; and by convection in hot climates, when the water vapor in suddenly rising masses of warm air cools and condenses. See also
hydrologic cycle.