Laboratoire de Mécanique des Fluides et d'Acoustique - UMR 5509

LMFA - UMR 5509
Laboratoire de Mécanique des Fluides et d’Acoustique

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Accueil > Équipes > Turbulence & Instabilités > Séminaires informels

Sylwester Arabas (Division of Computational Mathematics, Jagiellonian University, Cracow, Poland

Bifurcation analysis of CCN activation dynamics

Lundi 24 juin, 13h15, Salle de réunion I11 bas, ECL

Bifurcation analysis of CCN activation dynamics

Atmospheric clouds are visible to human eye for they are composed of water and ice particles that effectively scatter solar radiation. The multi-micrometre light-scattering cloud droplets form on sub-micrometre cloud condensation nuclei (CCN, a subset of atmospheric particulate matter). The size spectrum and chemical composition of CCN determine macroscopic properties of clouds such as their albedo and precipitation susceptibility.

A simple dynamical system modelling the formation and evaporation of cloud droplets will be introduced and scrutinised revealing a saddle-node bifurcation and a cusp catastrophe. The control parameters are the relative humidity and the particle concentration. Analysis of the bifurcations allows to analytically estimate the process timescale and the conditions for hysteretic behaviour. Relevance of the results in the context of development of particle-based models of clouds will be highlighted.


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