Clouds form when moist, warm rising air cools and expands in the atmosphere. The water vapor in the air condenses to form tiny water droplets which are the basis of clouds. On Earth, clouds are formed as a result of saturation of the air when it is cooled to its dew point, or when it gains sufficient moisture water vapor from an adjacent source to raise the dew point to the ambient temperature. The temperature profile of the atmosphere is a result of an interaction between radiation and convection. Sunlight in the visible spectrum hits the ground and heats it. The ground then heats the air at the surface. As air rises and cools, it eventually becomes saturated and cannot hold its quantity of water vapor. Meteorology forest winter autumn nature blue sky sunny day. Little cloud formation gradually. UHD 4K 3840×2160.