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| Titel |
Analysis of the effect of water activity on ice formation using a new thermodynamic framework |
| VerfasserIn |
D. Barahona |
| 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. 14 ; Nr. 14, no. 14 (2014-07-30), S.7665-7680 |
| Datensatznummer |
250118914
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| Publikation (Nr.) |
 copernicus.org/acp-14-7665-2014.pdf |
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| Zusammenfassung |
| In this work a new thermodynamic framework is developed and used to
investigate the effect of water activity on the formation of ice within
supercooled droplets. The new framework is based on a novel concept where the
interface is assumed to be made of liquid molecules "trapped" by the solid
matrix. It also accounts for the change in the composition of the liquid
phase upon nucleation. Using this framework, new expressions are developed for
the critical ice germ size and the nucleation work with explicit
dependencies on temperature and water activity. However unlike previous
approaches, the new model does not depend on the interfacial tension between
liquid and ice. The thermodynamic framework is introduced within classical
nucleation theory to study the effect of water activity on the ice nucleation
rate. Comparison against experimental results shows that the new approach is
able to reproduce the observed effect of water activity on the nucleation
rate and the freezing temperature. It allows for the first time a
phenomenological derivation of the constant shift in water activity between
melting and nucleation. The new framework offers a consistent thermodynamic
view of ice nucleation, simple enough to be applied in atmospheric models of
cloud formation. |
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