Interferometer observations of an intracloud lightning discharge

The spatial and temporal development of an intracloud lightning discharge has been observed by the VHF broadband interferometric system. A detailed study of the complete sequence of VHF radiation events during this intracloud flash has shown that this intracloud flash had a bilevel structure connected by a single upward channel. The flash had an inverted polarity in which the lower and upper level channels appear to correspond to the main positive and upper negative charge regions of the storm, respectively. The intracloud flash is characterized by active and final stages, each comprising about half of the overall flash duration. During the active stage, positive charge is transported upward in the cloud which establishes the upward channel. At the end of active stage the upward channel ceases to be conducting and the remaining final stage of the flash is indicated by the streamer breakdown at the lower-level channels.