Design of Thunder Imaging System and Observation for Ground and Intracloud Lightning Flashes

a sensitive acoustic sensor used to detect audible sound from lightning discharge is specially designed. The sensor employs a field-effect transistor circuit as preamplifier and a linear operation amplification for signal enhancement. A thunder imaging system is established, including acoustic sensor array, data acquisition system, and corresponding acquisition and analysis software. The system was used to observe thunder signal and lightning 3D structure in the JiangSu Province in the summer of 2016. The observation results indicate that the system can depict the three-dimensional discharge channels of lightning, and reveal the acoustic characteristics of different discharge channels in both time and frequency domain. The thunder sources are coincide with return stroke channel indicated by VHF results. The observation proves that thunder from ground flash is much stronger than cloud flash, with broader frequency band and larger pulse. The thunder sources are dominated in the vertical section in cloud flashes, which indicates that the vertical channel of cloud flash has a stronger current.