Articles | Volume 17, issue 22
Atmos. Chem. Phys., 17, 13509–13520, 2017

Special issue: Particle-based methods for simulating atmospheric aerosol...

Atmos. Chem. Phys., 17, 13509–13520, 2017

Research article 14 Nov 2017

Research article | 14 Nov 2017

Stochastic coalescence in Lagrangian cloud microphysics

Piotr Dziekan and Hanna Pawlowska

Model code and software

Model code P. Dziekan

The libcloudph++ cloud microphysics library S. Arabas, A. Jaruga, M. Waruszewski, D. Jarecka, and P. Dziekan

Short summary
Raindrops form when small cloud droplets collide with each other. In most computer models of clouds, this process is described using the Smoluchowski equation. We compare the Smoluchowski equation with computer simulations in which each droplet within a small part of the cloud is modeled. We show, depending on the simulation setup, that the Smoluchowski equation can give overly slow or fast rain formation. This implies that many cloud models used do not correctly represent rain formation.
Final-revised paper