Correlation Between Speed of the Leader and Peak Current of the Return Stroke in Negative Lightning Flashes

Abstract This study analyzes the two‐dimensional speed profiles of 107 stepped leaders and 93 dart leaders recorded by high‐speed cameras in Utah (USA), together with data from lightning location system. The results shows that the final and average speed of the stepped leader has a very strong (R = 0.82) and strong (R = 0.71) correlation with the peak current of the return stroke. It also shows that 91% of the stepped leaders increased their speed near the ground (average increase of 69%). The same analysis for dart leaders shows weak correlation with the peak current of the prospective return stroke (R = 0.39 to average speed and R = 0.28 to final speed). This paper briefly discusses why peak current is better correlated with final speed than with the average speed, and why stepped leaders exhibit a significant correlation, while dart leaders do not.