Lord Kelvin's atmospheric electricity measurements

TL;DR

Lord Kelvin's pioneering work in atmospheric electricity from 1859-1861 involved inventing measurement instruments, conducting environmental studies, and possibly detecting solar activity effects, laying groundwork for quantitative environmental physics.

Contribution

The paper details Kelvin's innovative instruments and methods for atmospheric electricity measurement, and highlights his early detection of solar activity effects on atmospheric potential gradient.

Findings

Kelvin invented the water-dropper instrument for PG measurement.

He developed a portable electrometer for field measurements.

Kelvin possibly detected atmospheric PG changes during the 1859 solar event.

Abstract

Lord Kelvin (William Thomson) made important contributions to the study of atmospheric electricity during a brief but productive period from 1859-1861. By 1859 Kelvin had recognised the need for "incessant recording" of atmospheric electrical parameters, and responded by inventing both the water-dropper instrument for measuring the atmospheric Potential Gradient (PG), and photographic data logging. The water-dropper was widely adopted internationally and is still in use today. Following theoretical considerations of electric field distortion by local topography, Kelvin developed a portable electrometer, using it to investigate PG on the Scottish island of Arran. During these environmental measurements, Kelvin may have unwittingly detected atmospheric PG changes during solar activity in August/September 1859 associated with the "Carrington event". Kelvin's atmospheric electricity work presents an early representative study in quantitative environmental physics, through the application of mathematical principles to an environmental problem, the design and construction of bespoke instrumentation for real world measurements and the limitations of the original theoretical view revealed by experimental work.