Observed Acoustic Radiation of Thunder Using Microphones Array

Lightning discharges can produce electromagnetic fields, light and thunder (shock waves). Thunder can be defined as the acoustic emission associated with all impulsive processes in cloud-to-ground (CG) and intra-cloud (IC) flashes, including M-component type processes. The acoustic signature of thunder can be used to better understand some of the properties of the lightning channel. Acoustic signatures generated by lightning flashes have been analyzed in the time domain in many previous studies for the quantitative identification of thunder features. To strengthen the previous findings, the acoustic signal frequency of a close flash and a distant flash were analyzed using the Fast Fourier Transform (FFT), the Short-time Fourier Transform (STFT), and instantaneous frequency. The results showed that there were differences between the frequencies of both flashes. The frequency of the acoustic signal of the close flash was higher than that of the distant flash. The frequency ranges of the acoustic signals of the close flash and the distant flash were 300 to 700 Hz and 100 to 400 Hz, respectively.