Wet hail and thunderstorm electrification

Jayaratne, Rohan & Saunders, Clive (2014) Wet hail and thunderstorm electrification. In MacGorman, Donald & Mansell, Ted (Eds.) 15th International Conference on Atmospheric Electricity (ICAE 2014), 15-20 June 2014, Norman, Oklahoma, USA. (Unpublished)


Hailstones in wet growth are commonly found in thunderclouds. While the ice-ice relative growth rate mechanism is generally accepted as the most likely cause of thunderstorm electrification, it is uncertain if this mechanism will operate under wet growth conditions because ice crystals are more likely to stick to the wet surface of a hailstone rather than bounce off it. Experiments were carried out in the laboratory to investigate if there was any charge separated when vapor-grown ice crystals bounced off a wet hailstone. A cloud of supercooled droplets, with and without ice crystals, was drawn past a simulated hailstone. In the dry growth regime, the hailstone charged strongly positive when droplets and crystals co-existed in the cloud. With only droplets in the cloud, there was no charging in the dry growth regime. However, as the hailstone attained wet growth, positive charging currents of about 0.5 and 3.5 pA were observed at 12 and 20 m s-1, respectively. We hypothesize that this observed charging was due to the evaporation of melt water. This so called Dinger-Gunn Effect is due to the ejection of negatively charged minute droplets produced by air bubbles bursting at the surface of the melt water. However the charge separated in wet growth was an order of magnitude smaller than that in dry growth and, therefore, we conclude that it is unlikely to play an important role in the electrification of thunderstorms.

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ID Code: 74618
Item Type: Conference Item (Presentation)
Refereed: No
Additional URLs:
Keywords: Lightning, Hail, Thundercloud, Ice crystals, Rime
Subjects: Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > ATMOSPHERIC SCIENCES (040100) > Cloud Physics (040106)
Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > ATMOSPHERIC SCIENCES (040100) > Meteorology (040107)
Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > ATMOSPHERIC SCIENCES (040100) > Tropospheric and Stratospheric Physics (040108)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute of Health and Biomedical Innovation
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2014 Please consult the authors
Deposited On: 01 Aug 2014 01:57
Last Modified: 02 Aug 2014 17:38

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