The compensation of the effects of potential-gradient variations in the measurement of the atmospheric air-earth current

✍ Scribed by J. Adamson; J. A. Chalmers

• Publisher: John Wiley and Sons
• Year: 1960
• Tongue: English
• Weight: 484 KB
• Volume: 86
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49708636814

✦ Synopsis

Abstract

A well‐known method of determining the atmospheric air‐earth current consists of collecting and measuring the current flowing into an insulated receiver at ground level. A difficulty encountered, however, is that any variation of the potential gradient produces a displacement of the bound charge on the collector, leading to a spurious ‘displacement’ current. In the simplest form of the method, this current can occasionally be so large as to mask completely the true‐earth current.

This article describes a development in which the sum of the air‐earth and displacement currents is measured at one terminal of a differential amplifier, while a field machine provides automatic and continuous compensation for the displacement current at the other terminal. The apparatus thus enables a continuous true recording of the air‐earth current to be made, and is an improvement on previous methods of eliminating the displacement current which necessitated intermittent recording of the integrated charge collected over a period of time. Satisfactory results are obtained with this method in all weather conditions except thunderstorms.