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| Titel |
Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation |
| VerfasserIn |
E. Stopelli, F. Conen, L. Zimmermann, C. Alewell, C. E. Morris |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 1 ; Nr. 7, no. 1 (2014-01-14), S.129-134 |
| Datensatznummer |
250115561
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| Publikation (Nr.) |
 copernicus.org/amt-7-129-2014.pdf |
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| Zusammenfassung |
| 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. |
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