Color analysis based on the color indices of lightning channels obtained from a digital photograph

Abstract

In this study, we present an analysis using the color indices B-G,B-R, and G-R of lightning channels obtained from a digital photograph. We used color-magnitude diagrams (CMDs) modified from the traditional CMDs employed in astronomical photometry, (B-G) versus (G-R) color-color diagrams (CCDs), two-dimensional (2D) color-index images for the color indices B-G,B-R, and G-R, and a 2D brightness image to analyze the colors and brightness of the lightning channels. The CMDs and CCDs for the lightning leader channels showed that the intensity of B-band and R-band light from those channels exceeds that of the G-band light. The 2D color-index images for B-G,B-R, and G-R and the 2D brightness image indicate spatial variations in the lightning channels. The spatial variabilities of the 2D color indices and 2D brightness indicate that the intensity of the B-band light exceeds that of the G- and R-band light around a bright channel with a high electric current (i.e., the plasma is highly ionized).