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| Titel |
On the role of non-electrified clouds in the Global Electric Circuit |
| VerfasserIn |
Andreas J. G. Baumgaertner, Greg Lucas, Jeffrey P. Thayer |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099052
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| Publikation (Nr.) |
 EGU/EGU2014-14795.pdf |
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| Zusammenfassung |
| Non-electrified clouds in the fair-weather part of the Global Electric Circuit reduce
conductivity because of the reduced mobility of charge due to attachment to cloud water
droplets. A high-resolution GEC model is used to show that for small clouds the cloud
resistance is less when considering current flow around the cloud, i.e. not limited to
only the vertical direction. For these clouds, the increased resistance vertically
through the cloud is larger than the horizontal resistances around the cloud, leading to
current convergence at the cloud edges above the cloud, and divergence below the
cloud. An analysis of this effect is presented for various types of non-electrified
clouds, i.e. for different altitude extents, and for different horizontal dimensions,
finding that the effect is most pronounced for small cirrus clouds. ISCCP cloud
data as well as the CESM1(WACCM) model is used to calculate the effect of this
phenomenon on total global resistance. It is found that when including non-electrified
clouds in the fair weather estimate of resistance the total global resistance increases
by between 130 and 170Ω, depending on the parameters used. Furthermore, the
non-electrified-cloud contribution to total resistance would be an additional 40Ω larger if
the current convergence/divergence phenomenon is neglected. Overall, a careful
treatment of these clouds appears to be necessary, contrary to previously assumed. |
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