Luminous Crown Residual Vs. Bright Space Segment: Characteristical Structures For The Intermittent Positive And Negative Leaders Of Triggered Lightning

We identify and investigate the intermittent propagation of upward positive and negative leaders in rocket-triggered lightning based on comprehensive observations of fine time-resolved optical, current, and electromagnetic fields. There is an abrupt luminous crown blooming due to the achievement of a positive leader step, after which the channel weakens and the head degrades. During the positive leader pausing, residual structure is recognized at area of previous luminous crown blooming, in the form of a floating segment. Our observation point to a possible mechanism that it connects with the positive leader head, causing a forward-step and a sharp current pulse. This is to some extent similar to negative leader stepping, in which the space leader emerges and connection between the space leader and the channel head occurs. The generation of clustered space leaders give rise to negative channel branching, but the residual structure in positive leader just leads to individual step.