Optical observation of one natural downward lightning stroke

This paper reports high-speed camera observation of one natural downward lightning flash in which the downward negative leader didn´t connect with the upward leader starting from a tall building in Wuhan city, Hubei Province, China. According to the observational data, several beneficial results are obtained such as the two-dimensional trajectory, the two-dimensional scale, speed and the duration time of the both downward and upward leaders. The observational results confirm that initiation and continuing development of upward leader cannot guarantee that the downward leader will successfully connect with the upward leader under the influence of random development of the downward leader. The observational results will help to achieve more reasonable selection of criterion in numerical simulation model of lightning flash.