Raindrops form in clouds when microscopic droplets of water grow or when particles of ice melt before reaching the ground. Rain falls throughout most of the world. In the tropics, almost all precipitation is rain. But in the inland areas of Antarctica, all precipitation is snow.
Rain is a part of an unending process known as the hydrologic cycle.
Some of the droplets may freeze, forming particles of ice. The droplets and particles then undergo a variety of changes in the clouds. Eventually, however, they fall to the surface as precipitation. Much of the precipitation that falls on continents eventually flows in rivers into the ocean. The process then repeats itself.