Cathode-Ray Oscillographic Investigations on Atmospherics

An analysis of the true nature of the wave forms of atmospherics, when they show rapid time variations, can easily be obtained by using cathode-ray oscillographs with very high speed recording. The author describes the arrangement that he has used for recording and analyzing atmospherics, with his relay construction of high voltage cathode-ray oscillographs. These instruments were connected through amplifiers to horizontal aerials having different heights above the ground. A passing atmospheric produced voltage changes across a resistor inserted in the antenna system, which, provided that special precautions were taken, gave the dE/dt variations of the field E. By applying an integration procedure to the records, it was possible to obtain the true field curves E(t) of the corresponding atmospherics. These observations were made at field stations located in the vicinity of the Institute of High Tension Research, University of Uppsala, Sweden. The results of observations made between February and August, 1934, are dealt with in this paper. About 7500 atmospherics were recorded, of which 600 were selected as typical, and have been integrated. The total duration times of individual atmospherics that were most frequently observed lay between 100 and 150 microseconds. When periodic or quasi-periodic variations were observed, about sixty per cent of such atmospherics showed a periodicity of between five and ten kilocycles per second. The atmospherics frequently occurred in groups composed of a number of separate and individual field variations. The time duration of about seventy per cent of such groups was within 5 × 10
^-2
seconds.