Abstract
PHOTOGRAPHIC records of electrical disturbances occurring during a thundercloud discharge, obtained with a cathode ray oscillograph, are submitted by Dr. F. W. Chapman. By means of a device in which the photographic film moves at right angles to the time-base deflection, electrical pulses only a few micro-seconds apart can be resolved. The records show a volley of discharges, presumably to be identified with the ‘brush’ discharge often observed in an active cloud as a prolonged flicker or flow, followed after a brief quiescent interval by the main lightning discharge. The volley radiates a long series of electromagnetic waves producing interference in radio receivers, while the main discharge consists of series of steps separated by 30-100 micro-seconds, their quasi-period corresponding to a wave-length of 15-30 km.
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Points from Foregoing Letters. Nature 139, 720 (1937). https://doi.org/10.1038/139720a0
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DOI: https://doi.org/10.1038/139720a0