Raining

Rain is liquid precipitation consisting of water droplets that fall from clouds to the Earth's surface. The droplets typically range from about 0.5 to 5 millimeters in diameter, and rain is usually more continuous and heavier than drizzle. It is a central component of the atmosphere–surface water cycle, contributing to soil moisture, rivers, and agricultural systems.

Rain forms when moist air rises, cools, and the water vapor condenses into cloud droplets. In warm, shallow clouds, droplets grow by collision and coalescence until they become too large to be supported by updrafts and fall as rain. In colder or mixed-phase clouds, the Bergeron process dominates: ice crystals grow at the expense of surrounding supercooled droplets, eventually melting into rain as they descend into warmer air.

Rain is often described by intensity: light rain, moderate rain, and heavy rain, with various local classifications. It can occur as steady rain, or as convective showers that are brief and uneven in duration. Rainfall is measured with rain gauges and is continuously mapped and forecast using weather radar and satellites.

Global rainfall patterns are uneven; the tropics receive abundant rain due to high evaporation and convection, while some regions experience arid conditions. Climate change is associated with shifts in rainfall intensity and distribution in many areas, influencing flood risk and water availability.

Rain supports ecosystems and agriculture by replenishing freshwater but can also cause flooding, erosion, and transportation disruptions.