Abstract The development behavior of lightning leaders directly reflects the electrical characteristics of thunderstorms. In plateau mountainous regions, cumulonimbus clouds are located at relatively low altitudes above the observation site. A negative cloud‐to‐ground (CG) lightning that vertically passed through an extended intermediate cloud patch was clearly recorded and was named traversing‐cloud lightning. As the stepped leader tip approached the cloud patch, it exhibited continuous acceleration. The two‐dimensional (2D) propagation speeds in the two frames before the leader tip entered the cloud patch were higher than the average speeds within the cloud patch. Near the upper edge of the cloud patch, the temperature, electron density and electric field intensity in the dart leader channel were about 3,200 K, 2.7 × 10 18 cm −3 and 2.5 × 10 7 V/m higher than those within tens of meters of the lower edge, respectively. These characteristics indicate that the intermediate cloud patch affected the development of the stepped leader and the variation of the physical parameters along the dart leader channel. We infer that the intermediate cloud patch carried a certain amount of positive charge, which modified the local charge distribution or electric field environment at the leader‐cloud interface. By combining the synchronous electric field variation data, the charge structure of the thunderstorm cloud associated with the formation of this traversing‐cloud CG lightning was reconstructed. Since the intermediate cloud patch is connected with the base of the thunderstorm cloud, we speculate that it might be a part of the positive charge region at the bottom of the thunderstorm cloud.
An et al. (Wed,) studied this question.