Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

UP: Fachverband Umweltphysik

UP 1: Poster Session

UP 1.5: Poster

Dienstag, 15. März 2011, 18:30–20:30, P2

Modeling the Droplet Size Distribution of Precipitation — •Ariane Papke and Jürgen Vollmer — Max Planck Institute for Dynamics and Self-Organization, 37073 Göttingen

In ice-free clouds, the primary process for the formation of precipitation is through the collision and coalescence of droplets falling at different velocities [1]. Due to their high sedimentation speed exceptionally large droplets dominate this process [2]. Similar behaviour is also observed in the phase separation of binary mixtures [3]. In that case the length scales (in particular the droplets) are much smaller, and the time scales are amenable to laboratory experiments. Based on an adapted version of model H for fluid-fluid phase separation we work out the time evolution for the droplet density. The results are compared to the experimental findings of Lapp et al for the phase separation of a binary mixture, and to rain formation in warm clouds.
[1] B. Stevens & G. Feingold, Nature 461 (2009) 607-613.
[2] A.B. Kostinski & R.A. Shaw, Bull Am Met Soc 86 (2005) 235-244.
[3] J. Vollmer, G.K. Auernhammer & D. Vollmer, Phys Rev Lett 98 (2007) 115701.