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| Titel |
Measurements of electric charge separated during the formation of rime by the accretion of supercooled droplets |
| VerfasserIn |
R. A. Lighezzolo, R. G. Pereyra, E. E. Avila |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2010-02-15), S.1661-1669 |
| Datensatznummer |
250008109
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| Publikation (Nr.) |
 copernicus.org/acp-10-1661-2010.pdf |
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| Zusammenfassung |
| In these experiments, the electric charge carried by single particles ejected
from the surface of a graupel particle growing by riming was measured. Simulated
graupel pellets were grown by accretion of supercooled water drops, at
temperatures ranging from −2 to −10 °C in a wind tunnel at air
velocities between 5 and 10 m s−1, with the goal of studying the
charging of graupel pellets under conditions of secondary ice crystal production
(Hallett-Mossop mechanism). The graupel, and induction rings upstream and
downstream of the graupel, were connected to electrometers and analyzing
circuits of sufficient sensitivity and speed to measure, correlate and display
individual charging events. The results suggest that fewer than 1% of the
ejected particles carry a measurable electric charge (>2 fC). Further, it was
observed that the graupel pellets acquire a positive charge and the average
charge of a single splinter ejected is −14 fC. This mechanism of ejection of
charged particles seems adequate to account for a positive charge of around 1 pC
that individual precipitation particles of mm-size could acquire in the lower
part of the cloud, which in turn could contribute to the lower positive charge
region of thunderstorms. |
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