Jena 2013 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 14: Atmosphäre - Spurengase, Aerosole und Labormessungen

UP 14.4: Vortrag

Donnerstag, 28. Februar 2013, 11:30–11:45, HS 5

Ice multiplication in freezing cloud droplets: Break-up — •Thomas Pander¹, Alexei Kiselev², and Thomas Leisner² — ¹Ruprecht-Karls-Universität Heidelberg — ²Karlsruher Institut für Technologie

Clouds are important for earth's precipitation and radiation budget. One of the determining factors of the lifetime of a cold cloud is the occurrence of a glaciation process, during which supercooled droplets freeze and may precipitate once they*ve grown to sufficient size. During this presentation, we report high-speed video evidence of one phenomenon that facilitates the glaciation of a cloud, a so-called secondary ice process. During a freezing event of a cloud droplet, a solid ice shell grows around a partly liquid core and may shatter under the rising pressure in the core due to the expansion during the phase transfer. The ice particles are propelled away at high speeds and may then cause freezing in other cloud droplets. Dependence on temperature, particle size and droplet diameter is explored and a potential enhancement factor of the ice nucleation capability of aerosol particles is given.