Syukuro Manabe and Richard T. Wetherald modelled an atmosphere relaxing toward radiative-convective equilibrium and studied its response to changes in factors including carbon dioxide. Their prescribed relative humidity lets water vapour change with temperature.[ref]
Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity by Syukuro Manabe and Richard T. Wetherald. 1967 Abstract: equilibrium model and water-vapour adjustment
This couples radiative transfer with vertical thermal adjustment, making the feedback assumptions explicit. A simpler dry or fixed-water-content atmosphere need not predict the same equilibrium response.
