Energy characteristics and the source of a ball lightning obtained by investigating its spectra

This work, based on quantitative spectrometric analysis, is an exploratory research on the radiated power density and its evolution feature of a ball lightning. The radiated power density has shown a periodic pulse feature, like the spectral characteristics and temperature evolution of this BL. We proposed that this BL may be the discharge from the residual charge at the bottom of the previous cloud-to-ground (CG) lightning channel initiating it. Meanwhile, the electromagnetic field produced by the power line may be a potential outside energy source that supports the life of the BL. The optical radiation from soil constituent dominates the bright light of this BL.