Researchers have identified lightning bolts in Oklahoma and France as the longest on record and warn that their discovery could alter traditional thinking on when it's safe to go outside after a storm has passed.

A 2007 storm in Oklahoma produced a lightning bolt nearly 200 miles long, while a storm in southern France in 2012 produced a single flash that lasted 7.74 seconds. Both events were added Wednesday to a list of weather extremes kept by the World Meteorological Organization.

Timothy Lang from NASA said the Oklahoma lightning bold streaked from near Tulsa to near the Oklahoma Panhandle. Randy Cerveny at Arizona State University, said that the French storm produced a lightning bolt that doubled back on itself, extending its life.