Field disturbances produced by lightning

THE present knowledge of the mechanism of natural lightning permits more accurate calculation of its electric and magnetic fields than has hitherto been possible. In a previous paper,
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the electric ground gradients for nearby strokes to earth were treated principally for the determination of the voltages induced on transmission lines by indirect strokes. In this paper the study is extended to the fields produced at greater distances. Knowledge of the character of such fields is important because of their relationship to stroke mechanism and electrical cloud conditions in general. They also are sources of interference to radio and telephony communication and can cause sparking which may be serious in structures constituting a fire or explosion hazard.