Jena 2013 – scientific programme

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UP: Fachverband Umweltphysik

UP 10: Atmosphäre - Spurengase, Aerosole und Labormessungen

UP 10.4: Talk

Wednesday, February 27, 2013, 14:45–15:00, HS 5

Heterogeneous Ice Nucleation of Micrometer Sized Water Droplets on Well Defined Surfaces — •Moritz Haarig, Isabelle Steinke, and Thomas Leisner — Karlsruher Institut für Technologie (KIT), Institut für Meteorologie und Klimaforschung - Atmosphärische Aerosolforschung (IMK-AAF))

Ice nucleation in clouds has an impact on global climate, because it influences the structure of clouds and thus precipitation and the global radiative budget. Often, aerosol particles are found to be immersed in water droplets where they initiate the formation of ice. However, it is still not clear which characteristics of the aerosol particles are important for being good ice nuclei.

In our experiment, we have created a testbed for immersion freezing where we can investigate the freezing of several hundreds of water droplets on well-characterized surfaces. We present freezing curves for silicon, copper and graphite and also the corresponding heterogeneous ice nucleation rates. We have also investigated the surface roughness of these materials with an atomic force microscope. Furthermore, in future studies we will change the surface properties of certain materials by chemical etching. This gives us the opportunity to learn more about the influence of different morphologies on the process of ice nucleation.