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| Titel |
Charging of ice-vapor interfaces: applications to thunderstorms |
| VerfasserIn |
J. Nelson, M. Baker |
| 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 ; 3, no. 4 ; Nr. 3, no. 4 (2003-08-27), S.1237-1252 |
| Datensatznummer |
250001152
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| Publikation (Nr.) |
 copernicus.org/acp-3-1237-2003.pdf |
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| Zusammenfassung |
| The build-up of intrinsic Bjerrum and ionic defects at ice-vapor interfaces electrically
charges ice surfaces and thus gives rise to many phenomena including thermoelectricity,
ferroelectric ice films, sparks from objects in blizzards, electromagnetic emissions
accompanying cracking in avalanches, glaciers, and sea ice, and charge transfer during
ice-ice collisions in thunderstorms. Fletcher's theory of the ice surface in equilibrium
proposed that the Bjerrum defects have a higher rate of creation at the surface than in
the bulk, which produces a high concentration of surface D defects that then attract a
high concentration of OH- ions at the surface. Here, we add to this theory the effect of a
moving interface caused by growth or sublimation. This effect can increase the amount
of ionic surface charges more than 10-fold for growth rates near 1 mm
s-1 and can extend the spatial separation of interior charges in qualitative agreement with many
observations. In addition, ice-ice collisions should generate sufficient pressure to melt
ice at the contact region and we argue that the ice particle with the initially sharper point
at contact loses more mass of melt than the other particle. A simple analytic model of
this process with parameters that are consistent with observations leads to predicted
collisional charge exchange that semiquantitatively explains the negative charging
region of thunderstorms. The model also has implications for snowflake formation,
ferroelectric ice, polarization of ice in snowpacks, and chemical reactions in ice
surfaces |
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