Direct measurements of the atmospheric conduction current

Abstract

A new method of measuring the atmospheric conduction current above the ground has been employed to obtain data for 12 weeks during the first half of 1974. The instrument consists of a split aluminum sphere suspended by insulated wires to a wooden frame. The measuring electronics and the transmitter are enclosed within the spherical structure. The interaction of the instrument with its atmospheric electrical environment is analyzed, and it is shown that in steady state conditions, predictable differences in the instrumentally measured currents and the atmospheric conduction current will be less than 5% and in the nonsteady state situations the difference is less than 20%. Diurnal variations, a probable winter‐summer variation, sunrise, and fog effects were observed for the data obtained during fair‐weather conditions. Disturbed weather data are interpreted for the effects of low clouds on the atmospheric current. The charge concentrations within overcast clouds sufficient to produce the observed reversed atmospheric currents are estimated to be small (around ±5 ×10 −12 C/m3) in relation to values in thunderclouds (around ± 10−10 C/m3).

Diurnal variation of atmospheric Maxwell current over the low-latitude continental station, Tirunelveli, India (8.7°N, 77.8°E)

“…As the fog dissipates, the evaporation of water drops leads to a slow recovery of the conductivity, and the current returns to the initial values. Burke and Few (1978) observed a similar fog effect on the air-Earth current density measured at Houston.…”

“…Widely used ground-based sensors for the measurement of air-Earth current are the Wilson plate (Israel, 1973), the horizontal long-wire antenna (Kasemir, 1955;Ruhnke, 1969) and the spherical shell in the form of two hollow hemispheres (Burke and Few, 1978). The long-wire antenna allows for the suppression of local disturbances by averaging the vertical current over a large area (Ruhnke, 1969).…”

A comparative study of atmospheric Maxwell current and electric field from a low latitude station, Tirunelveli

“…The space charges that exist at the time of evaporation from dew or mist may contribute to the observed variations in electrical parameters (Karasnogorskaya and Pokhmelnik, 1983, for example). The variations observed in I and E at this low latitude station differ markedly from those reported from other low and middle latitudes (Israel, 1973;Burke and Few, 1978;Reiter, 1985;Adlerman and Williams, 1996). Israel (1973) found no characteristic fundamental behavior among the measurements from ten continental stations.…”

The Global Atmospheric Electrical Circuit and Climate

“…The Gerdien instrument continues to provide the physical basis on which modern ion counting instruments are still designed (Blakeslee and Krider, 1992;Hõrrak et al, 1998), although computer control of the bias voltage and current measurements is becoming more common Harrison, 2000, 2001;Holden, 2004). Direct measurement of the air-Earth current has been achieved using a split-hemisphere collector, suspended above the surface, within which the current amplifiers are housed (Burke and Few, 1978). This has also proved durable under Antarctic conditions (Byrne et al, 1993).…”