Convective storms and atmospheric vertical structure in Uranus and Neptune

Area of Science:

• Planetary Science
• Atmospheric Physics
• Fluid Dynamics

Background:

• Ice giants Uranus and Neptune possess hydrogen-based atmospheres with unique cloud-forming constituents.
• Observed cloud systems differ from gas giant storms, suggesting methane and deeper hydrogen sulfide (H2S) and ammonia hydrosulfide (NH4SH) clouds.

Purpose of the Study:

• To investigate the distinct moist convective regimes in the deep atmospheres of ice giants.
• To understand the thermal structure and atmospheric dynamics influenced by stabilizing molecular weight gradients.

Main Methods:

• Analysis of existing observational data for cloud systems on Uranus and Neptune.
• Thermochemical modeling to predict cloud formation at various atmospheric depths.
• Comparison with atmospheric models of gas giants and terrestrial planets.

Main Results:

• Moist convection in ice giants is significantly inhibited by strong molecular weight gradients, differing from gas giants.
• Deep weather layers are predicted, involving ammonia hydrosulfide (NH4SH) and water clouds at high pressures.
• Observed cloud properties suggest methane condensation and deeper H2S clouds.

Conclusions:

• The thermal structure of ice giant atmospheres remains poorly understood due to inhibited vertical motion.
• Ice giants offer unique opportunities to study moist convection in hydrogen-rich atmospheres.
• Combined orbital and in situ data are crucial for future exploration and understanding of these planets and exoplanets.