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Surface Crystallization of Cloud Droplets: Implications for Climate Change and Ozone DepletionThe process of supercooled liquid water crystallization into ice is still not well understood. Current experimental data on homogeneous freezing rates of ice nucleation in supercooled water droplets show considerable scatter. For example, at -33 C, the reported freezing nucleation rates vary by as much as 5 orders of magnitude, which is well outside the range of measurement uncertainties. Until now, experimental data on the freezing of supercooled water has been analyzed under the assumption that nucleation of ice took place in the interior volume of a water droplet. Here, the same data is reanalyzed assuming that the nucleation occurred "pseudoheterogeneously" at the air (or oil)-liquid water interface of the droplet. Our analysis suggest that the scatter in the nucleation data can be explained by two main factors. First, the current assumption that nucleation occurs solely inside the volume of a water droplet is incorrect. Second, because the nucleation process most likely occurs on the surface, the rates of nuclei formation could differ vastly when oil or air interfaces are involved. Our results suggest that ice freezing in clouds may initiate on droplet surfaces and such a process can allow for low amounts of liquid water (approx. 0.002 g per cubic meters) to remain supercooled down to -40 C as observed in the atmosphere.
Document ID
20020064488
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Tabazadeh, A.
(NASA Ames Research Center Moffett Field, CA United States)
Djikaev, Y. S.
(California Univ. Los Angeles, CA United States)
Reiss, H.
(California Univ. Los Angeles, CA United States)
Gore, Warren J.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Environment Pollution
Meeting Information
Meeting: 87th Statistical Mechanics Conference
Location: NJ
Country: United States
Start Date: May 19, 2002
End Date: May 21, 2002
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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