Twentieth-century atmospheric electrical measurements at the observatories of Kew, Eskdalemuir and Lerwick

摘要

The atmospheric electrical system arises from the combination of thunderstorm electrification and the slight ionisation of air. Thunderstorms separate charge, carrying positive charge up to the conductive ionosphere and negative charge to the earth'ssurface. There is therefore an electrical potential difference between the ionosphere and the surface. This causes a small current to flow between the ionosphere and the surface, with an associated potential gradient (PG) existing near the surface (Fig.1). Atmospheric electricity was probably originally studied because of the PG's sensitivity to local changes, attracting such eminent scientists as C. T. R. Wilson and Lord Kelvin. General introductions to atmospheric electricity are given in MacGormanand Rust (1998), Chalmers (1967), Israel (1973) and Harrison (2000a).