Heidelberg 2015 – scientific programme
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UP: Fachverband Umweltphysik
UP 4: Postersession Atmosphäre
UP 4.24: Poster
Wednesday, March 25, 2015, 10:45–19:45, G/Foyer
Forward scattering by levitated ice crystals — •Mohamed Abdelrasoul1,2, Alexei Kiselev2, and Thomas Leisner2,3 — 1Karlsruhe School of Optics and Photonics KSOP (KIT), Karlsruhe — 2Institute for Meteorology and Climate Research (KIT), Karlsruhe — 3Institute of Environmental Physics, University of Heidelberg
Ice clouds have a significant impact on the energy budget of the earth-atmosphere system, as solar and terrestrial radiation interacts with earth's atmosphere. Cirrus clouds are made of non-spherical ice crystals which can take on a variety of shapes, from regular habits such as plates, columns and bullet- rosettes, to irregular habits, the shape of ice crystals being determined by the temperature and pressure of water vapor in the vicinity of a growing or evaporating ice crystal. The radiative properties of ice clouds depend on the optical properties of ice crystals, which can be best studied under laboratory conditions. With this goal in mind, we have built an optical system allowing for measurements of the two dimensional forward scattering patterns of the ice crystals that are freely levitated in an electrodynamic balance (EDB) of a quadrupole type. The temperature and relative humidity inside the balance are controlled. High dynamic range CMOS camera is used to record the forward scattering by a single ice crystal illuminated with circularly polarized 532 nm laser beam. The recorded scattering patterns are analyzed for characteristic features of different crystal habits and surface morphology (smooth or rough).