Hydrogen-bomb explosions can generate their own lightning. Ground-level
detonations, like this 1952 test of an experimental thermonuclear device on
Eniwetok in the South Pacific, cause a negative charge to be deposited in the
atmosphere, resulting in long discharges not produced by clouds. This is a
frame from movie footage shot at a distance of about 18 miles from ground zero.
The lightning channels have been enhanced for visibility.