Preprints
https://doi.org/10.5194/egusphere-2026-3906
https://doi.org/10.5194/egusphere-2026-3906
21 Jul 2026
 | 21 Jul 2026
Status: this preprint is open for discussion and under review for Geoscientific Model Development (GMD).

Exploring Cloud Microphysics Modeling Concepts the Pythonic Way

Sylwester Arabas, Agnieszka Żaba, Daria Klimaszewska, Emma C. Ware, Clare E. Singer, Manhal Alhilali, Jason Barr, Daniel G. Partridge, Shin-ichiro Shima, and Robert Wood

Abstract. We share with the community a concise Pythonic codebase for hands-on exploration of cloud microphysics modeling concepts. It includes an adiabatic air-parcel model simulating diffusional droplet growth – leading to condensation, activation, evaporation, and ripening; as well as a box model resolving collisional growth of particles using the Super-Droplet Method Monte-Carlo scheme. Leveraging Pythonic abstractions and programmatic unit handling, the code combines pseudo-code-level readability, auditability, and dimensional-correctness enforcement with high performance through just-in-time (JIT) compilation, which generates native machine code on the fly, avoiding bytecode interpretation overhead for compute-heavy routines. With the goal of illustrating how concise yet complete implementations support both teaching and research software engineering, the paper includes and narrates the entire code, plotting logic included. The code runs with a single click "in the cloud" – on Google Colab or other Jupyter hubs, and thus constitutes a suitable resource for self-study or for a short course in microphysics modeling. Presented technical solutions originate from the PySDM particle-based simulation package, but are applicable in a wider scope and independently of PySDM as exemplified here. The paper includes section-wise exploratory exercises designed to guide further application of the methods and concepts discussed.

Competing interests: At least one of the (co-)authors is a member of the editorial board of Geoscientific Model Development.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Sylwester Arabas, Agnieszka Żaba, Daria Klimaszewska, Emma C. Ware, Clare E. Singer, Manhal Alhilali, Jason Barr, Daniel G. Partridge, Shin-ichiro Shima, and Robert Wood

Status: open (until 16 Sep 2026)

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Sylwester Arabas, Agnieszka Żaba, Daria Klimaszewska, Emma C. Ware, Clare E. Singer, Manhal Alhilali, Jason Barr, Daniel G. Partridge, Shin-ichiro Shima, and Robert Wood
Sylwester Arabas, Agnieszka Żaba, Daria Klimaszewska, Emma C. Ware, Clare E. Singer, Manhal Alhilali, Jason Barr, Daniel G. Partridge, Shin-ichiro Shima, and Robert Wood
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Latest update: 22 Jul 2026
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Short summary
The paper focuses on the use of Python and its package ecosystem for modeling the dynamics of atmospheric aerosol and cloud droplets. We highlight that concise code and high-level abstractions (incl. programmatic expression of physical units) can be used without performance tradeoffs. The paper features two cloud-microphysics classics: an adiabatic parcel model and a Monte-Carlo coagulation solver. The presented code constitutes a single Jupyter notebook that can be executed "in the cloud".
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