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| Titel |
Heterogeneous ice nucleation activity of bacteria: new laboratory experiments at simulated cloud conditions |
| VerfasserIn |
O. Möhler, D. G. Georgakopoulos, C. E. Morris, S. Benz, V. Ebert, S. Hunsmann, H. Saathoff, M. Schnaiter, R. Wagner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 5, no. 5 ; Nr. 5, no. 5 (2008-10-21), S.1425-1435 |
| Datensatznummer |
250002837
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| Publikation (Nr.) |
 copernicus.org/bg-5-1425-2008.pdf |
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| Zusammenfassung |
| The ice nucleation activities of five different Pseudomonas syringae,
Pseudomonas viridiflava and Erwinia herbicola bacterial species
and of Snomax™ were investigated in the temperature range
between −5 and −15°C. Water suspensions of these bacteria
were directly sprayed into the cloud chamber of the AIDA facility of
Forschungszentrum Karlsruhe at a temperature of −5.7°C.
At this temperature, about 1% of the Snomax™ cells
induced immersion freezing of the spray droplets before the droplets evaporated
in the cloud chamber. The living cells didn't induce any detectable immersion
freezing in the spray droplets at −5.7°C. After evaporation
of the spray droplets the bacterial cells remained as aerosol particles in the
cloud chamber and were exposed to typical cloud formation conditions in
experiments with expansion cooling to about −11°C. During
these experiments, the bacterial cells first acted as cloud condensation nuclei
to form cloud droplets. Then, only a minor fraction of the cells acted as
heterogeneous ice nuclei either in the condensation or the immersion mode.
The results indicate that the bacteria investigated in the present study are
mainly ice active in the temperature range between −7 and −11°C
with an ice nucleation (IN) active fraction of the order of 10−4. In
agreement to previous literature results, the ice nucleation efficiency of
Snomax™ cells was much larger with an IN active fraction of
0.2 at temperatures around −8°C. |
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