Correlation between speed of the stepped leader and peak current of the
return stroke of 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 (NLDN). The
results show that the stepped leader speed right before the ground
contact (final speed) has a very strong correlation (R = 0.85) with the
peak current of the initiated return stroke. It also shows that the
correlation between the average speed and the peak current of the return
stroke is strong (R = 0.73). The same analysis for dart leaders did not
show any significant correlation with the peak current of the
prospective return stroke (R = 0.41 to average speed and R = 0.29 to
final speed). This paper discusses why stepped leaders exhibit a
significant correlation, while dart leaders do not. In addition, why
final speed is better correlated with peak current than average speed.