Acoustic output of a long spark

In a recent paper [Few et al., 1967] measurements of the average power spectrum of thunder were reported. The results indicated a very broad maximum at about 200 Hz. A short theoretical analysis was also given that set a lower limit on the expected dominant frequency of about 57 Hz. In the analysis, the dominant frequency was shown to be inversely proportional to the square root of the energy per unit length dissipated in the discharge channel.