First experimental verification of opacity for the lightning near‐infrared spectrum

Using the spectral data of a lightning continuing discharge process observed on the 600-m-high Canton Tower, experimental verification of the optical thickness of lightning neutral nitrogen (NI) and neutral oxygen (OI) radiation in the near-infrared spectrum is presented first by comparing the measured relative intensities of two NI multiplets with theoretical values. For the first time, the spectral evolution characteristics of the tall structure lightning continuing discharge process show that visible band singly ionized lines were apparent for approximately 320-400 mu s. The ionized lines with higher excitation energies and the neutral lines with lower excitation energies coexist for approximately 240-320 mu s, which means that there is a hot region radiating ionized lines in a radial direction from the lightning channel, but at the same time there is also a cold region radiating neutral lines.