Electrostatic field‐changes due to lightning discharges

TLDR

Lightning discharges generate dominant electrostatic field changes within 100 km. The study investigates how meteorological factors influence the relative frequency of cloud versus ground discharges. Capillary‑electrometer recordings amplified by auxiliary equipment provide statistical relationships between field magnitude, distance, and sign for lightning flashes. Analysis shows that most of the field change occurs slowly and can be divided into distinct groups with measurable electric moments and stage times.

Abstract

Abstract Extensive observations are described of the changes of electrical field produced by lightning discharges at distances of less than 100 km; in this range electrostatic effects are dominant. The results are analysed in detail. A long series of capillary‐electrometer records obtained with auxiliary amplifying equipment give statistical information upon the magnitude‐distance and sign‐distance relationships for the total electrostatic field‐change due to a lightning flash. From oscillographic observations it is shown that most of this change in field occurs comparatively slowly. It has proved possible to separate field‐changes into distinct groups; these are considered in turn and values given for such quantities as the electric moment and the times involved in each stage, etc. Finally, meteorological influences and the relative frequency of occurrence of cloud and ground discharges are investigated.