Astro-seminar Aerosols and Clouds: Why the Shape of Tiny Particles Matters for Exoplanets by Matthew Lodge

Clouds and hazes can play a crucial role in shaping planetary climates by contributing significantly to atmospheric absorption and scattering. While many atmospheric models assume their constituent particles to be spherical, this simplification can lead to inaccuracies in predicting their optical and dynamical behaviour. These inaccuracies, in turn, can result in errors in the properties that we retrieve from telescope data. In this talk, I explore how we can characterize the properties of irregular, non-spherical particles more accurately while retaining speed in models. I compare the mathematical foundations of spherical versus non-spherical particle models, highlighting the physical implications and computational challenges involved. I introduce MANTA-Ray, a novel model that can compute accurate absorption cross-sections up to 1013 times faster than traditional rigorous methods. In addition, I present recent work as the lead developer of VIRGA v2.0, a major upgrade of the widely used cloud code. This new version incorporates non-spherical particle physics for the first time, and I will share the exciting first results, demonstrating the substantial impact of particle shape on transmission spectra -- with important implications for interpreting observational data and modelling planetary atmospheres.