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Exoplanet atmosphere characterisation is an important tool in understanding the formation and evolution of exoplanets, in addition observations coupled with microphysical models provide excellent laboratories to explore novel atmospheric regimes. However, clouds remain a key challenge in observation as they both alter the local atmospheric composition through condensation and obscure deeper atmospheric layers. With next-generation instruments such as the James Webb Space Telescope (JWST) a detailed understanding of cloud formation processes will be required to interpret observations.
Most observed gas-giant exoplanets host mineral clouds which could form snowflake-like structures through condensation and constructive collisions. Cloud particle porosity, size and number density are influenced by constructive and destructive collisions. We investigate the effects on clouds of collisional growth and fragmentation due to gravitational settling, brownian motion and turbulence. We include cloud particle porosity in our kinetic non-equilibrium cloud formation model to explore the effects of non-compact cloud particles for 1D pressure-temperature Drift-Phoenix profiles. We utilise Mie theory and effective medium theory to study cloud optical depths for micro-porous particles. Additionally, we calculate the optical depth of clouds for the Drift-Phoenix profiles, where we further represent non-spherical cloud particles with a statistical distribution of hollow spheres. We find both porosity and non-sphericity enhance cloud optical depth at silicate feature wavelengths, observable with JWST MIRI.

Cloud Nine Con | Dominic Samra | Mineral Snowflakes: Porosity and Non-Sphericity of Cloud Particles