Abstract
The scattering greenhouse effect of a CO2 ice cloud layer may expand the outer edge of the habitable zone in which a terrestrial planet have warm and wet climate. This study explores how the scattering greenhouse effect depends on the planetary mass or surface gravity by using a CO2-H2O atmosphere model taking into account the radiative adjustment processes for CO22 ice cloud profile. For a planet with the surface gravity and solar flux equivalent to those of paleo-Mars at 3.8Ga, a CO2 ice cloud layer which can cause strong greenhouse effect is possibly formed. In this case, the global mean surface temperature rises above the melting point of H2O when the surface pressure is larger than 3 bar and the mixing ratio of cloud condensation nuclei is kept within the range 106 - 107 kg-1. As the surface gravity increases, the atmospheric pressure required for such warm climate tends to increase.
