Séminaire IPAG

Hazes and Clouds: The Architects of (Exo-)Planetary Climates

jeudi 24 septembre 2026 - 11h00
Bruno de Batz - LIRA
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Hazes and clouds play a fundamental role in shaping the climates of planetary bodies throughout the Solar System and beyond. By interacting with incoming stellar radiation and outgoing thermal emission, they strongly influence atmospheric temperatures, radiative balance, and circulation, thereby affecting both short-term meteorology and long-term climate evolution. Clouds can act as thermal regulators by reflecting incoming sunlight or trapping infrared radiation, while hazes absorb and scatter radiation, redistribute energy throughout the atmosphere, and can strongly interact with atmospheric dynamics. Recent advances in observations and climate modeling have significantly improved our understanding of these phenomena, while also highlighting the importance of comparative studies to refine our theories of planetary climates. Understanding how hazes and clouds form, evolve, and interact with atmospheric dynamics is therefore essential to accurately characterize planetary climates and assess their potential habitability, both within our Solar System and beyond. In this talk, I will first review the diversity of hazes and clouds observed across the Solar System. I will then present a new microphysical model coupled to a General Circulation Model, enabling a detailed investigation of the formation, evolution, and atmospheric transport of hazes and clouds. I will apply this framework to Titan, showing that the climate of its troposphere is governed by complex interactions between clouds and condensate mists, while its stratosphere is primarily controlled by photochemical hazes and their strong feedbacks with atmospheric circulation. I will then turn to Pluto, where I will show how even tenuous atmospheric hazes can substantially modify its thermal structure. Finally, I will broaden the discussion to the ice giants and sub-Neptunes, highlighting how the same physical processes may shape the climates of worlds far beyond our Solar System.

Salle Manuel Forestini, 414 rue de la piscine, 38400 Saint Martin d'Hères