Condensation Clouds in Substellar Atmospheres with Virga

Abstract Here we present an open-source cloud model for substellar atmospheres, called Virga . The Virga-v0 series has already been widely adopted in the literature. It is written in Python and has heritage from the A. S. Ackerman & M. S. Marley model (often referred to as eddysed ), used to study clouds on both exoplanets and brown dwarfs. In the development of the official Virga-v1 we have retained all the original functionality of eddysed and updated/expanded several components, including the back-end optical constant data, calculations of the Mie properties, available condensate species, saturation vapor pressure curves, and formalism for fall speed calculations. Here we benchmark Virga by reproducing key results in the literature, including the SiO 2 cloud detection in WASP-17 b and the brown dwarf Sonora Diamondback model series. Development of Virga is ongoing, with future versions already planned and ready for release. We encourage community feedback and collaborations within the GitHub code repository.