Clouds of Neptune and Uranus

Abstract

We present results on the bases and concentrations of methane ice, ammonia ice, ammonium hydrosulfide-solid, water ice, and aqueous-ammonia solution (droplet) clouds of Neptune and Uranus, based on an equilibrium cloud condensation model. Due to their similar p-T structures, the model results for Neptune and Uranus are similar. Assuming 30-50x solar enhancement for the condensibles species, as expected from formation models, we find that the base of the droplet cloud is at the 370 bars for 30 solar, and at 500 bars for 50 solar cases. Despite this, entry probes need to be deployed to only 50-100 bars to obtain all the critical information needed to constrain models of the formation of these planets and their atmospheres.