Effect of cloud formation on the structure and transport properties in planetary atmospheres

Presenter: Kensuke NAKAJIMA
In planetary atmospheres, formation of clouds affects stability and transport properties in several ways. In Earth’s atmosphere, condensing component, H2O, is lighter than the major atmospheric component, convection by the release of latent heat enhances convection. In Jovian atmospheres, where cloud forming component is heavier than the major component, convection can be suppressed, or even inhibited (Guillot, 1995). In the case when major constituent condenses, buoyancy can hardly be allowed because density of condensing parcel is constrained by the saturation relation between pressure and temperature. In this presentation, I will discuss the convection inhibition criteria concerning the formation of NH4SH cloud by the chemical reaction of NH3 and H2S, which have not considered quantitatively so far. The result shows convection is indeed suppressed at about 30 times the Solar abundance of heavy elements. I will also discuss possible mechanism of vertical energy transport that can work even in such convection inhibited states, considering the importance of gravitational sedimentation of condensed phase.