HIGH-SPEED PHOTOGRAPHIC ANALYSIS OF INTRACLOUD LIGHTNING RADIATION-FIELDS

The radiation fields of 14 intracloud discharges have been analyzed. The intracloud discharges are initiated by an upward moving predischarge from the lower negative charge center propagating in steps and known as an L-change. The main discharge, known as a K-change, immediately follows the L-change and moves downwards from the upper positive charge center with high velocity and luminosity. The durations of the flashes, and the L-change and K-change intervals, have been determined. The initial and very active portions of the L-change are found to contain nearly uniform pulses of radiation with a mean interval ranging from 2.9 to 7.5 ms. The corresponding value for the K-change is 4.8 ms. For L-changes the standard deviation ranges from 2.5-6.7 ms while for the K-change it ranges from 0.83-13.38 ms. The average charge destroyed by an intracloud flash is 11.0 C while the average charge moment destroyed is 86.0 C km. The average step length and velocity for L-changes have been observed to be 108 m and 2.29 x 10(4) m/s respectively.