Relationship Between X‐Rays and the Propagation Speed of Downward Negative Leaders in Rocket‐Triggered Lightning

Abstract On 18 July 2023, X‐ray emissions associated with two rocket‐triggered lightning flashes were observed at the Field Experiment Base for Lightning Sciences, China Meteorological Administration. In this paper, the relationship between X‐ray characteristics and propagation speed of downward negative dart leaders is analyzed for the first time. Results show that within the same lightning flash, there is a strong positive correlation between the leader brightness and its 2D speed, as evidenced by a high correlation coefficient, R , of +0.94. Consistently, the intensity of X‐rays generally exhibits a positive correlation with the leader 2D speed. Conversely, the average X‐ray pulse interval is negatively correlated with the leader 2D speed, with a significant correlation coefficient, R , of −0.93. Furthermore, the intervals of partial steps of dart leader can be characterized by the intervals between the X‐ray pulses.