Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation

Stopelli, Emiliano and Conen, Franz and Zimmermann, Lukas and Alewell, Christine and Morris, Cindy E.. (2014) Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation. Atmospheric measurement techniques, Vol. 7. pp. 129-134.

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Official URL: http://edoc.unibas.ch/dok/A6211864

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For decades, drop-freezing instruments have contributed to a better understanding of biological ice nucleation and its likely implications for cloud and precipitation development. Yet, current instruments have limitations. Drops analysed on a cold stage are subject to evaporation and potential contamination. The use of closed tubes provides a partial solution to these problems, but freezing events are still difficult to be clearly detected. Here, we present a new apparatus where freezing in closed tubes is detected automatically by a change in light transmission upon ice development, caused by the formation of air bubbles and crystal facets that scatter light. Risks of contamination and introduction of biases linked to detecting the freezing temperature of a sample are then minimized. To illustrate the performance of the new apparatus we show initial results of two assays with snow samples. In one, we repeatedly analysed the sample (208 tubes) over the course of a month with storage at +4 °C, during which evidence for biological ice nucleation activity emerged through an increase in the number of ice nucleators active around −4 °C. In the second assay, we indicate the possibility of increasingly isolating a single ice nucleator from a precipitation sample, potentially determining the nature of a particle responsible for a nucleation activity measured directly in the sample. These two seminal approaches highlight the relevance of this handy apparatus for providing new points of view in biological ice nucleation research.
Faculties and Departments:05 Faculty of Science
05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Umweltgeowissenschaften (Alewell)
UniBasel Contributors:Conen, Franz and Alewell, Christine and Stopelli, Emiliano and Zimmermann, Lukas
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:31 Dec 2015 10:54
Deposited On:31 Jan 2014 09:50

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