![]() ESA Annual Meeting on Electrostatics 2014. “Electrical charging of volcanic ash” by Karen Aplin, Isobel Houghton, Keri Nicoll, Michael Humphries and Alex Tong, 2014, Proc.Gilbert, 10 July 2000, Journal of Geophysical Research: Solid Earth. “Volcanic plume electrification: Experimental investigation of a fracture-charging mechanism” by M.Harrison, 20 July 2006, Surveys in Geophysics. “Electrification of volcanic plumes” by T.Burgin, 14 December 2011, Journal of Geophysical Research: Solid Earth. “Charge mechanism of volcanic lightning revealed during the 2010 eruption of Eyjafjallajökull” by Pordur Arason, Alec J.Yet, whatever the mechanism, there’s no doubt it’s a spectacular occurrence! More research should hopefully provide a better understanding of what is happening during a strike. While the science behind volcanic lightning is not complete, many factors are known to play a role. For smaller plumes, the suggestion is that most of the electric buildup comes from fractoemission near the vent, reducing the chances of a strike. With more water present and colder ambient temperatures at this height, there is likely more ice charging and more electrical activity. When an eruption results in a tall ash plume (greater than 7 km), there is a higher water vapor concentration. While not a mechanism in its own right, plume height can significantly impact whether lightning occurs. The extent radioactive charging has on volcanic lightning is unknown, although it may be a significant contributor in some instances. Studies have shown that ash particles have natural radioactivity above the usual level, and charged areas can form when they decay. Natural radioisotopes within the rock may influence charge buildup. This effect predominantly occurs at high energy, resulting in the charge congregating closer to the volcano’s vent. When the rock breaks, it is possible for charged particles to form, forming a buildup of static charge. Similar to frictional charging is fractoemission, which is the breakup of rock particles within the plume. The conventional currents that cause the plume to rise then separate this charge into different regions. In the same way that ice charging occurs due to ice particles colliding, rock fragments and ash collide and create charged ions. These positively charged ice ions continue to rise and congregate higher in the atmosphere.įrictional charging, also known as triboelectric charging, is also thought to be a crucial mechanism leading to volcanic lightning. The water in the plume freezes into ice particles that collide with one another, knocking electrons from the crystals. As the warm air from the eruption rises into the sky, it meets colder air in the atmosphere. Ice charging is the primary mechanism by which regular thunderstorms form, and it also plays a role in volcanic lightning, particularly those where the plume rises high into the air.
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