Meteorological experts have established two new world records for the furthest distance and the longest duration of single lightning strikes.
The research has prompted a change to the formal definition of what constitutes a “lightning discharge”.
The furthest reported distance record has been confirmed as a lightning bolt over Oklahoma in June 2007, which covered a horizontal distance of 321km (200 miles).
The longest reported duration of a continual lightning strike was in Provence-Alpes-Côte d'Azur in southern France in 2012, when a storm saw a single strike last for 7.74 seconds.
The World Meteorological Organisation (WMO) said that “dramatic improvements” in remote sensing techniques in recent years have allowed the detection of previous unobserved extremes in lightning occurrence.
This enabled the WMO committee to conduct a critical evaluation to confirm the records.
Lightning is a major weather hazard that claims many lives each year,” WMO Secretary-General Petteri Taalas said. “Improvements in detecting and monitoring these extreme events will help us improve public safety.”
In a statement, the WMO said: “As part of their evaluation, the committee also unanimously agreed that the existing formal definition of ‘lightning discharge’ should be amended to a ‘series of electrical processes taking place continuously’ rather than the previously specified time interval of one second.
“This is because technology and analysis have improved to the point that lightning experts now can detect and monitor individual lightning flashes with lifetimes much longer than a single second.”
The investigating committee was made up of lightning and meteorological experts from the US, France, Australia, China, Spain, Morocco, Argentina and the UK.
Randall Cerveny, the chief rapporteur of climate and weather extremes for the WMO said: “This investigation highlights the fact that because of continued improvements in meteorology and climatology technology and analysis, climate experts can now monitor and detect weather events such as specific lightning flashes in much greater detail than ever before.
“The end result reinforces critical safety information regarding lightning, specifically that lightning flashes can travel huge distances from their parent thunderstorms.”
He added: “Our experts’ best advice: when thunder roars, go indoors.”
