From a distance, lightning can be beautiful, fascinating and terrifying—even surpassing the fear factor of a potential Sharknado. Now, a pair of extreme records recently certified by the World Meteorological Organization show that lightning has an even longer reach than previously thought.
On June 20, 2007, during a thunder storm in Oklahoma, a lighting bolt streaked across half the state. This is the longest lightning bolt ever recorded, stretching 199.5 miles from outside Tulsa to the Texas border, according to a press release. Originating at an altitude of six miles, the lightning touched down in several locations on its journey and was visible as far away as Colorado.
So just how does a lightning bolt span 200 miles? Most lightning is considered “negative lighting” in which a cloud unleashes a negative charge to the ground. Most of these bolts max out at about six miles in length. But according to the National Weather Service, roughly five percent of lightning strikes are “positive lightning” in which a positive charge is discharged from top of the cloud to the ground. These bolts carry much more energy and travel up to 25 miles and carry ten times the energy of a negative bolt, up to 1 billion volts. If storms are particularly strong and atmospheric conditions are just right, these powerful thunderbolts can travel tens or hundreds of miles.
A second extreme occurred in Provence-Alpes-Côte d'Azur, France, on August 30, 2012. On that day, a single lightning flash persisted for 7.74 seconds, setting the record for lightning duration. Both records are detailed in the Bulletin of the American Meteorological Society.
The two lightning incidents mark the first time that the World Meteorological Organization has included lightning in its Archive of Weather and Climate Extremes. But these records also forced scientists to rethink the definition of lightning. These extremes and others prompted the WMO to formally amend the definition of lightning from a “series of electrical processes taking place within one second” to a “series of electrical processes taking place continuously.”
It's also causing weather mavens to rethink lightning safety advice. “[B]ecause 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,” Randall Cerveny, Rapporteur of Climate and Weather Extremes for WMO says in the press release. “The end result reinforces critical safety information regarding lightning, specifically that lightning flashes can travel huge distances from their parent thunderstorms. Our experts’ best advice: when thunder roars, go indoors.”
The current standard advice is the 30/30 rule, according to Kelly Kissel at the Associated Press. After seeing a flash of lightning, if the thunder rumbles within 30 seconds, go indoors for 30 minutes until the danger passes. “These kinds of rules need to be looked at,” Timothy Lang, from NASA's Marshall Space Flight Center tells Kissel. “It’s going to depend on the kind of thunderstorm. You really need to know where it (lightning) is occurring. There could be a lower risk—the lower the flash rate—but it’s not ‘no-risk.’”
According to Angela Fritz at The Washington Post, the average number of lightning deaths in the U.S. have been under 50 per year since 2000, well below the 400 people per year who died in strikes in the 1940s. This year so far, lightning has killed 35 individuals in the states.