III. Atmospheric electricity in high latitudes

Abstract

Investigation into the problems of atmospheric electricity may be divided into two periods. The first period was devoted almost entirely to measurements of the normal potential gradient in the lower region of the earth’s atmosphere, with the aim of finding its daily and yearly variations, its geographical distribution and its dependence on meteorological condition. To this period belongs the fine work of Lord Kelvin and Professor Exner. The second period commenced in 1899, when the interest in the problems of atmospheric electricity was at rather a low ebb, owing to the small real progress made during the latter few years. In that year the discovery that atmospheric air is always more or less ionized—made at about the same time by Elster and Geitel in Germany and C. T. R. Wilson in England—had a completely revolutionizing influence on the theories held to account for the earth’s normal field. This discovery has brought about a great revival of interest and opened a totally new field for investigation.