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Authors: Weitzel, Maximilian
Mitra, Subir K.
Szakáll, Miklós
Fugal, Jacob P.
Borrmann, Stephan
Title: Application of holography and automated image processing for laboratory experiments on mass and fall speed of small cloud ice crystals
Online publication date: 28-Jan-2021
Year of first publication: 2020
Language: english
Abstract: An ice cloud chamber was developed at the Johannes Gutenberg University of Mainz for generating several thousand data points for mass and sedimentation velocity measurements of ice crystals with sizes less than 150 µm. Ice nucleation was initiated from a cloud of supercooled droplets by local cooling using a liquid nitrogen cold finger. Three-dimensional tracks of ice crystals falling through the slightly supersaturated environment were obtained from the reconstruction of sequential holographic images, automated detection of the crystals in the hologram reconstructions, and particle tracking. Through collection of the crystals and investigation under a microscope before and after melting, crystal mass was determined as a function of size. The experimentally obtained mass versus diameter (m(D)) power law relationship resulted in lower masses for small ice crystals than from commonly adopted parameterizations. Thus, they did not support the currently accepted extrapolation of relationships measured for larger crystal sizes. The relationship between Best (X) and Reynolds (Re) numbers for columnar crystals was found to be X=15.3 Re1.2, which is in general agreement with literature parameterizations.
DDC: 530 Physik
530 Physics
540 Chemie
540 Chemistry and allied sciences
Institution: Johannes Gutenberg-Universität Mainz
Department: FB 09 Chemie, Pharmazie u. Geowissensch.
Place: Mainz
Version: Published version
Publication type: Zeitschriftenaufsatz
License: CC BY
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Journal: Atmospheric chemistry and physics
Pages or article number: 14889
Publisher: EGU
Publisher place: Katlenburg-Lindau
Issue date: 2020
ISSN: 1680-7324
Publisher URL:
Publisher DOI: 10.5194/acp-20-14889-2020
Appears in collections:JGU-Publikationen

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