Abstract
We report the observation of three negative upward flashes recorded by a high-speedcamera at the Säntis Tower during the Summer of 2019. The camera was operating at 10, 000 fps andan exposure time of 99 μs. Simultaneous measurements of the lightning current were obtained for allthree flashes. The close electric field was measured for one of the observed flashes, which was analyzedin detail. In this flash, we observed 50 recoil leaders developing in the decayed channel with speedscharacteristic of dart leader processes. Out of the 50 recoil leaders, 45 ended up as attempted leaders, threedeveloped into M-component-type ICC (initial continuous current) processes, and two into return strokes.This study reveals that depending on the spatial and temporal properties of electric field in the area ofthe event and the main channel condition, recoil leaders can develop into different processes in upwardnegative lightning flashes such as attempted leaders, M- components, M-component-type ICC events, mixed mode pulses, or return strokes. We observed M- component-type ICC events with junction heightsas low as 137 m, while all of the observed mixed mode pulses seemed to attach directly to the structure.Bidirectional propagation of the recoil leader was also observed. (PDF) Bidirectional Recoil Leaders in Upward Lightning Flashes Observed at the Säntis Tower. Available from: https://www.researchgate.net/publication/354303504 Bidirectional_Recoil_Leaders_in_Upward_Lightning Flashes_Observed_at_the_Santis_Tower [accessed Jan 19 2023].
Antonio Šunjerga
Assistant Professor | Department of Electrical Engineering Fundamentals
Researcher and assistant professor at the Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture in Split, with research interests that include lightning physics, lightning protection, and electromagnetic compatibility.