Berlin 2014 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 10: Atmosphäre - Aerosole

UP 10.5: Vortrag

Mittwoch, 19. März 2014, 16:00–16:15, MAG 100

Nucleation and growth of ice on the substrates of K-feldspar observed in ESEM — •Alexei Kiselev, Andreas Peckhaus, and Thomas Leisner — Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research

Atmospheric mineral dust particles, originating from arid regions such as the Sahara, are known to have a strongly variable mineralogical composition. The main components they are composed of are(in order of diminishing average weight content): clay minerals (e.g. kaolinite), micas (e.g. illite), quarts, feldspars, and calcite. These minerals are characterized by different ice nucleating efficiency, which describes the freezing probability of supercooled cloud droplet due to the presence of mineral dust particle serving as a heterogeneous ice nucleus (IN). Potassium (K) feldspar, although not the main component of atmospheric mineral dust, was shown recently to be one of the most effective ice nuclei among airborne mineral dust particles, potentially being responsible for the overall IN efficiency of feldspar-containing mineral dusts (Atkinson et al., 2013). In this contribution we describe the deposition ice nucleation experiments carried out on the freshly cleaved substrates of K-feldspar in an Environmental Scanning Electron Microscope (ESEM). We also compare this approach to the immersion freezing results obtained with similar substrates and droplets of aqueous suspensions of feldspar particles on a cold stage. Comparison to literature data and atmospheric implications will be discussed as well.

Atkinson et al., The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds, in Nature 498, 355-358 (2013);