Rain clouds are a type of cloud formation that is composed of water droplets or ice crystals suspended in the atmosphere. They are formed when warm, moist air rises and cools, condensing into droplets of water or ice. The term 'rain clouds' can refer to two different types of clouds: nimbostratus and cumulonimbus. Nimbostratus clouds are low-level clouds that produce steady rain or snow. Nimbuses are large, dense clouds that produce heavy rain or snow. Wetformation is a term used to describe the process of condensation that occurs when warm, moist air rises and cools, forming rain clouds.