700 km Brazilian “megaflash” sets lightning record

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Geneva (AFP)

The UN weather agency announced the longest lightning strike on record on Thursday – a single lightning bolt in Brazil on October 31, 2018 that crossed the sky for more than 700 kilometers.

This is equivalent to the distance between Boston and Washington DC in the United States, or between London and Basel, Switzerland, the World Meteorological Organization said in a statement.

The WMO Committee of Experts on Extreme Weather and Climate also reported a new world record for the duration of a lightning strike, with a single flash that developed continuously over northern Argentina March 4, 2019 for a total duration of 16.73 seconds.

The new “megaflash” records, which were verified with new satellite imagery technology, were more than double the previous known record holders, the WMO said.

The previous record for the longest distance detected by a single flash was 321 kilometers (199 miles), measured on June 20, 2007 in the US state of Oklahoma, the WMO said.

The previous duration record was 7.74 seconds, measured on August 30, 2012 in the south of France, according to the press release.

– “Extraordinary records” –

The new measures reveal “extraordinary records of single lightning events,” said Randall Cerveny, chief reporter for the WMO expert panel.

“It is likely that even greater extremes still exist and that we will be able to observe them as lightning detection technology improves,” he said.

Previous records have been evaluated using data collected from terrestrial networks of lightning mapping networks, which many lightning scientists recognize as being faced with upper limits on the scale of lightning that can be observed said WMO.

He praised recent advances in spatial lightning mapping, which measure “the extent and duration of continuous flash across large geospatial areas.”

This helped to detect “previously unobserved lightning strikes called mega-flashes,” said Michael J. Peterson of the Space and Remote Sensing Group at the Los Alamos National Laboratory in the United States, in the release.

Mega flashes, he said, “are defined as horizontal mesoscale lightning discharges that are hundreds of kilometers long.”

United Nations agency occasionally reveals weather milestones, as in 2016, revealing a record wave measurement of a giant that peaks at 19 meters (62.3 feet) – higher than a six-story building – over the North Atlantic.

All of these records are kept in the WMO archives of extreme weather and climate conditions.

The archive currently includes two other lightning extremes.

One concerns the largest number of people killed by a single direct lightning strike, when 21 people died in Zimbabwe in 1975 while they were gathering to secure themselves in an affected hut.

The other is for an indirect strike, when 469 people died in Dronka, Egypt, when lightning struck a set of oil tanks in 1994, causing the combustion of oil that flooded the city.

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