Continuing current (CC) in cloud-to-ground (CG) lightning plays a critical role, particularly in wildfire ignition, yet its mechanism remains an open question. This study analyzes a two-stroke CG flash captured by a high-speed camera and the Beijing Lightning Network (BLNET). The first return stroke exhibits a larger peak current with a very short CC, while the subsequent stroke features a smaller peak current but significantly prolonged CC. We find that the short CC is linked with vigorous negative branches after the stroke, while the long CC correlates with nearly the absence of negative branches. Positive leaders collect negative charges from the cloud, driving the negative leaders in the bidirectional leader tree. Sustained CC requires continuous positive leader propagation; however, ungrounded negative leaders compete for cloud charge after stroke, influencing CC duration. This study provides novel insights into CC mechanisms and suggests a new method to evaluate CC duration.

continuing current,negative cloud-to-ground lightning