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Titel |
Ice particles in the upper anvil regions of midlatitude continental thunderstorms: the case for frozen-drop aggregates |
VerfasserIn |
J. L. Stith, L. M. Avallone, A. Bansemer, B. Basarab, S. W. Dorsi, B. Fuchs, R. P. Lawson, D. C. Rogers, S. Rutledge, D. W. Toohey |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 4 ; Nr. 14, no. 4 (2014-02-20), S.1973-1985 |
Datensatznummer |
250118417
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Publikation (Nr.) |
copernicus.org/acp-14-1973-2014.pdf |
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Zusammenfassung |
This study examines the occurrence and morphology of frozen-drop aggregates
in thunderstorm anvils from the United States Midwest and describes the environmental
conditions where they are found. In situ airborne data collected in anvils
using several particle imaging and sizing probes and bulk total water
instrumentation during the 2012 Deep Convective Clouds and Chemistry
experiment are examined for the presence of frozen-drop aggregates. Chains
of frozen drops have been only rarely reported before and are hypothesized
to aggregate due to electrical forces in the clouds. They were identified in
nine of the anvil cases examined to date, suggesting that they are common
features in these Midwestern anvils. High concentrations of individual
frozen droplets occurred on the tops and edges of one particular set of
anvils, while regions closer to the center and bottom of these anvils
exhibited fewer frozen drops and more frozen-drop aggregates. Bulk ice water
content measurements across these anvils could only be explained by
contributions from both small particles (frozen droplets) and large
particles (large aggregates of frozen droplets). Dual Doppler radar analysis
confirmed the presence of deep and strong (> 15 m s−1)
updrafts in the parent cloud of one of the anvils. These features contrast
with previous anvil measurements in tropical/maritime anvils that evidently
do not exhibit the same frequency of frozen-drop aggregates. |
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