An experimental study of electric field pulses produced by cloud and ground lightning discharges

Measurements of electric fields produced by cloud and ground lightning discharges were performed in Gainesville, Florida, in the summer of 2006. Microsecond- and submicrosecond-scale pulses in both cloud and cloud-to-ground discharges associated with the initial breakdown process were recorded and analyzed. In addition to ldquoclassicalrdquo preliminary breakdown pulses with durations of some tens of microseconds, pulses with durations an order of magnitude smaller were also detected. A total of 12 cloud and 12 cloud-to-ground discharges were analyzed in detail. We estimated that 26% of the pulses in the 12 cloud discharges and 22% of the pulses in the 12 cloud-to-ground discharges had total durations less that 1 mus. Further, we documented (apparently for the first time) pulse trains that were characteristic of initial (preliminary) breakdown in negative cloud-to-ground flashes but were not followed by return-stroke pulses.