Researchers have identified a burst of high-energy radiation
known as ‘dark lightning” immediately preceding a flash of ordinary lightning.
The new finding provides observational evidence that the two phenomena are
connected, although the exact nature of the relationship between ordinary
bright lightning and the dark variety is still unclear, the scientists said.
“Our results indicate that both these phenomena, dark and
bright lightning, are intrinsic processes in the discharge of lightning,” said
Nikolai Østgaard, who is a space scientist at the University of Bergen in
Norway and led the research team.
He and his collaborators describe their findings in an
article recently accepted in Geophysical Research Letters—a journal of the
American Geophysical Union.