On the occurrence of recoil leaders in negative upward flashes in Brazil

The processes that give origin to the current pulses during the initial continuous current (ICC), M-components and return strokes in upward flashes are subject of recent studies and require further understanding. Apparently, the common aspect behind these processes relies on the physics that govern the recoil leaders (RL), which is presently not well understood. This study uses high-speed cameras to record images of 80 upward lightning flashes in Sao Paulo, Brazil. From these videos some characteristics of the recoil leaders were analyzed: time interval between the initiation of the positive upward leader and the occurrence of the first RL; the height of the tip of the upward positive leader when the RLs occur; where in the channel the RL initiates; the relationship between branching and presence of RLs, and the initiation of ICC pulses, M-components and dart leaders by RLs.