Explicit Habit‐Prediction in the Lagrangian Super‐Particle Ice Microphysics Model McSnow.

The Monte‐Carlo ice microphysics model McSnow is extended by an explicit habit prediction scheme, combined with the hydrodynamic theory of Böhm. Böhm's original cylindrical shape assumption for prolates is compared against recent lab results, showing that interpolation between cylinder and prolate yields the best agreement. For constant temperature and supersaturation, the predicted mass, size, and density of the ice crystals agree well with the laboratory results, and a comparison with real clouds using the polarizability ratio shows regimes capable of improvement. An updated form of the inherent growth function to describe the primary habit growth tendencies is proposed and combined with a habit‐dependent ventilation coefficient. The modifications contrast the results from general mass size relations and significantly impact the main ice microphysical processes. Depending on the thermodynamic regime, ice habits significantly alter depositional growth and affect aggregation and riming. The influence of primary ice behavior on precipitation formation needs to be considered in future development of microphysical parameterizations, but the consideration of secondary habits and the geometry of aggregates should be further improved in future work. Plain Language Summary: The McSnow model was extended to predict the shape of ice crystals. A comparison of the falling behavior of modeled and 3D‐printed ice crystals shows a discrepancy that can be improved by interpolation. At constant temperature and supersaturation, simulated crystal properties agree well with laboratory results, and by comparison to real clouds, we have updated the function to describe growth tendencies. Ice shape is shown to have a significant influence on the main microphysical processes. Key Points: McSnow is extended by an explicit habit prediction including the revision of corresponding parameterizationsA new inherent growth ratio overcoming existing deficiencies is proposedThe impact of the modifications on the depositional growth, aggregation, and riming is shown for two distinct case studies [ABSTRACT FROM AUTHOR]