Luminosity Variation during Propagation of Lightning Channels

Luminosity variations of natural cloud-to-ground lightning flashes were studied by analyzing a set of high speed video recordings. The frame rate and resolution of the camera was 5000 fps at 512×512 pixel resolution. The frames were stored as black and white sequence (SEQ) files which were converted to sequence of image files using the software provided by the camera. Algorithms were developed to scan the image files and extract maximum brightness of channels as well as maximum brightness at selected locations along the channels. The variation of current along the channel was analyzed by assuming that the brightness of the channel is directly proportional to the current that flows through it. The study shows that there is a loss of current in lightning channels when current flowing through the channel. The amount of current reduction increases with the propagating distance. Preliminary estimates show that there is approximately 3% reduction in current when propagation from cloud-to-ground.