Leader–streamers nature of blue jets

Abstract

A new model of blue jets as a lightning-related phenomenon is proposed. A blue jet consists of the bi-leader, whose top part is seen on photos as a “trunk of a tree”, and is capped at the topside of the leader by its streamer zone. The latter is shown as tall and narrow branches of “the tree”. It is shown that the time independent fractal blue jet model does not provide an adequate description of blue jets and streamer zone of a leader. It ignores an important fact of the fast loss of the streamer channel conductivity due to the electron attachment to the oxygen. The top streamer branches were born mostly prior to the bottom branches not as result of branching, but formed by the leader tip. It was shown that due to transfer of the high potential of the edge of the thundercloud by the leader, long streamers of blue jets can be sustained by moderate cloud charge. The streamer length is estimated along with the height at which the streamers can reach the ionosphere. The propagation of a streamer in the atmosphere of exponentially falling density N and in the self-consistent electric field of the streamer zone was computed. It was found that the critical external field E S required for unlimited streamer growth satisfies the similarity law E S/ N⋍const. The similarity law was numerically studied in a wide range of N.