In atmospheric thermodynamics, the virtual temperature () of a moist air parcel is the temperature at which a theoretical dry air parcel would have a total pressure and density equal to the moist parcel of air.[1] The virtual temperature of unsaturated moist air is always greater than the absolute air temperature, however, as the existence of suspended cloud droplets reduces the virtual temperature.
The virtual temperature effect is also known as the vapor buoyancy effect.[2] It has been described to increase Earth's thermal emission by warming the tropical atmosphere.[3][4]