The meteorology of non-global atmospheres on lava planets

Giang Nguyen ( Université McGill )

Lava planets are tidally locked rocky planets that orbit so closely to their star that stellar radiation can vapourize their molten rocky surfaces to form a thin atmosphere. Despite the permanent dayside of lava planets being hot enough to generate a substantial atmosphere, the nightside is expected to be cold enough for the atmosphere to condense back onto the surface. This scenario is very hard for global circulation models to handle and therefore studying the various aspects of atmospheric dynamics on these planets require a more fundamental approach. We use a 1D hydrodynamical model to infer the evaporation/condensation rate as well as atmospheric temperatures and wind speeds. We also explore how the radiative properties of a silicate atmosphere affect the overall dynamics. We discovered that because radiative cooling in the UV requires a high temperature threshold to be effective, atmospheric temperatures therefore will tend to converge at a point where UV radiative cooling and stellar absorption balances one another. We also found that a strong temperature inversion leads to faster horizontal winds which can be attributed to the impediment of vertical motion in the atmosphere allowing for only horizontal flow.