High-speed plasma imaging: a lightning bolt

Using a gated intensified digital Kodak Ektapro camera system, we captured a lightning bolt at 1000 frames per second, with 100-/spl mu/s exposure time on each consecutive frame. As a thunder storm approached while darkness descended (7:50 pm) on July 21, 1994, we photographed lightning bolts with an f22 105-mm lens and 100% gain on the intensified camera. This 15-frame sequence shows a cloud to ground stroke at a distance of about 1.5 km, which has a series of stepped leaders propagating downwards, followed by the upward-propagating main return stroke.