Secondary ice formation during freezing of levitated droplets.

Lauber, Annika, Kiselev, Alexei, Pander, Thomas, Handmann, Patricia and Leisner, Thomas (2018) Secondary ice formation during freezing of levitated droplets. Open Access Journal of the Atmospheric Sciences, 75 (8). pp. 2815-2826. DOI 10.1175/JAS-D-18-0052.1.

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Abstract

The formation of secondary ice in clouds, i.e. ice particles that are created at temperatures above the limit for homogeneous freezing without the direct involvement of a heterogeneous ice nucleus is one of the longest standing puzzles in cloud physics. Here we present comprehensive laboratory investigations on the formation of small ice particles upon the freezing of drizzle-sized cloud droplets levitated in an electrodynamic balance. Four different categories of secondary ice formation (bubble bursting, jetting, cracking, breakup) could be detected and their respective frequencies of occurrence as a function of temperature and droplet size are given. We find that bubble bursting occurs more often than droplet splitting. While we do not observe the shattering of droplets into many large fragments, we find that the average number of small secondary ice particles released during freezing is strongly droplet-size dependent and may well exceed unity for droplets larger than 300 μm in diameter. This leaves droplet fragmentation an important secondary ice process effective at temperatures around -10 °C in clouds where large drizzle droplets are present.

Document Type: Article
Keywords: Atmosphere; Clouds; Ice crystals; Ice particles
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1175/JAS-D-18-0052.1
ISSN: 0022-4928
Projects: ATMO
Date Deposited: 05 Jul 2018 14:20
Last Modified: 01 Mar 2019 00:38
URI: http://oceanrep.geomar.de/id/eprint/43584

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