Optical Progressing and Electric Field Change Characteristics of Altitude—Triggered Lightning Flash With Different Development Paths

Abstract

Abstract The characteristics of optical and electric field waveforms from altitude triggered lightning flash at Guangzhou Field Experiment Site for Lightning Research and Testing (GFESLRT) during the summer of 2019 are presented. The altitude triggered lightning flash had eight return strokes with nine M‐components along four development paths. And the terminal heights of four paths are over 1,626 m above the ground. Our study presented an arithmetic mean of 0.62 kV/m and an arithmetic mean of 0.63 ms of half‐peak width for 16 initial continuous current (ICC) pulses values, as well as an arithmetic mean of 1.24 kV/m and an arithmetic mean of 0.47 ms of half peak width for nine M‐components values. The average 2‐D speed ranged from 3.80°× 10 5 to 2.94 × 10 6 m/s for the attempted leaders and from 1.26 × 10 6 to 6.96 × 10 6 m/s for the dart leaders. Basically, the greater the downward leader’s 2‐D propagation speed, the larger the electric field change. The electric field waveform in the rising edge of return stroke can be divided into three parts: “SF” indicates the slow front of the return stroke; “FT” indicates the fast transition of the return stroke; “SS” indicates shoulder structure of the return stroke. The arithmetic mean of SF electric field change is 1.45 kV/m and that of SF risetime is 110.6 μs. The arithmetic mean of the first FT electric field change is 4.71 kV/m and that of the first FT risetime is 1.1 μs. The arithmetic mean of the SS electric field change is 3.89 kV/m and that of the SS risetime is 28.1 μs.