a) Simulated vertical temperature profiles for Gl 581c. Dash and dotted-line: dry atmosphere with P_s = 1 bar and 50 ppmv of CO₂, Dashed-line: moist atmosphere with P_s = 1 bar, 50 ppmv of CO₂, and same water-vapor mixing ratio as in the Earth atmosphere, and solid line: moist atmosphere with P_s = 1 bar, 50 ppmv CO₂, fixed relative humidity same as in Manabe and Wetherald (1967). A cloud layer is located between 700 and 100 hPa marked by horizontal dotted-lines. b) Vertical profiles of water-vapor volume mixing ratio. The solid and dashed-lines in b) correspond to the solid and dashed-lines in a), respectively.