Vertical current flow through extensive layer clouds |
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| Authors: | KA Nicoll RG Harrison |
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| Institution: | 1. Aintree University Hospitals NHS Trust;2. Department of OMFS, RWTH Aachen University Hospital, Aachen, Germany;3. MKG - Chirurgie Lindenarcaden;4. Portsmouth Hospital;5. Institute of Dentistry, Barts and The London;1. Howard University, 2355 6th Street NW, Washington, DC 20059, USA;2. Atmospheric Sciences Research Center, State University of New York at Albany, Albany, NY 12203, USA;1. FAU Erlangen-Nürnberg, Institute of Geography, Wetterkreuz 15, 91054 Erlangen, Germany;2. Leiden University, Faculty of Archaeology, Einsteinweg 2, 2333 CC Leiden, Netherlands;3. University of Vienna, Institute of Classical Archaeology, Franz-Klein Gasse 1, 1190 Vienna, Austria |
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| Abstract: | The global atmospheric electrical circuit sustains a vertical current density between the ionosphere and the Earth's surface, the existence of which is well-established from measurements made in fair-weather conditions. In overcast, but non-thunderstorm, non-precipitating conditions, the current travels through the cloud present, despite cloud layers having low electrical conductivity. For extensive layer clouds, this leads to space charge at the upper and lower cloud boundaries. Using a combination of atmospheric electricity and solar radiation measurements at three UK sites, vertical current measurements have been categorised into clear, broken, and overcast cloud conditions. This approach shows that the vertical “fair weather” current is maintained despite the presence of cloud. In fully overcast conditions with thick cloud, the vertical current is reduced compared to thin cloud overcast conditions, associated with the cloud's resistance contributions. Contribution of cloud to the columnar resistance depends both on cloud thickness, and the cloud's height. |
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