Audio-Frequency Spectrum of Atmospherics

Abstract

THE observations on the low-frequency or ‘slow tail’ component in the waveform of an atmospheric described recently by Hepburn and Pierce in Nature1 is of particular interest to us since we have been making similar observations for some years. The earlier observations made by Appleton and Chapman2 dealt with the evolution of atmospheric waveforms. It was shown that many atmospherics consist of an oscillatory portion, composed of a sequence of quasi half-cycles of increasing duration, followed by a ‘slow tail’ of usually two rounded half-cycles. The oscillatory portion was found to move ahead of the slower disturbance as the distance of propagation increased. Further, the quasi half-period of the components of the oscillatory portion was found to obey a relation different from the ‘slow tail’.