The relation between lightning discharges and atmospherics in radio receiving

Abstract

In order to examine the relations between lightning discharges and atmospherics cathode ray oscillographs were applied to record the variation forms of atmospherics. By simultaneous observations of atmospherics, by the aid of the loud speakers of radio receiving sets and corresponding records by cathode ray oscillographs the existence of two characteristic variation forms of atmospherics in connection with thunderstorms were obtained, ( a) “the clicks”-singular discharges of a comparatively short duration (up to some hundred microseconds) and caused by shorter local sparks, ( b) “the grinders” whistling or hissing perturbation forms in the loud speakers. The corresponding oscillograms resulted in complicated variation forms of the same type as the Author had observed to be usual in ordinary lightning discharges. The relation to lightning was further investigated in an indirect manner. By cathode ray oscillographic records atmospherics of ordinary types with their centres of origin at greater distances from the locality of observations were examined. These atmospherics showed in most cases very characteristic variation forms with more or less pronounced and superimposed periodic or quasiperiodic variation. The main problem was how to explain the generation of these variation forms from known discharges as they were observed at the most probable centres of emission—e.g. lightning paths. For that purpose the transmission equation for radio waves was applied on such discharge variation forms which had been observed to be usual in partial lightning discharges. From the calculation it was concluded that atmospherics with typical variations could be derived from lightning discharges with known and uncomplicated variation forms fixed by cathode ray oscillographic recording. The sometimes apparently complicated variation forms of atmospherics of the short variation type were thus in the most cases found to be a secondary effect caused by gradual deformation during transmission.