Direct measurement of lower atmospheric vertical potential differences

Abstract

A high impedance system has been developed to make direct measurements of the atmospheric potential difference up to several thousand feet. A tethered balloon flown from Wallops Island, Virginia was used to loft a high voltage, insulated wire and a conducting collector in a test flight to 550 meters for two days of experiments in October 1980. The balloon was equipped with a payload to measure exact altitude, wind speed and direction, and other meteorological parameters. Electric potentials of 170,000 volts at 550 meters were measured. The collected currents which could be drawn through the wire by grounding the lower end were in the 10 microamp range indicating a system impedance of about 1010 ohms. This paper will describe the apparatus and details of these measurements.

Measurements of Atmospheric Electricity Aloft

“…The maximum potential measured by Willett and Rust (1981) was 195kV, at a height of 5.3km above mean sea level, and 170kV at a height of 0.55km by Holzworth et al (1981). Concerns about the validity of the measurements by Holzworth et al (1981) were expressed by Markson (1984), who pointed out that the potential measurements were unusually large compared to previous aircraft measurements at the same height.…”

“…The maximum potential measured by Willett and Rust (1981) was 195kV, at a height of 5.3km above mean sea level, and 170kV at a height of 0.55km by Holzworth et al (1981). Concerns about the validity of the measurements by Holzworth et al (1981) were expressed by Markson (1984), who pointed out that the potential measurements were unusually large compared to previous aircraft measurements at the same height. Although the tethered balloon technique of measuring V I generally permits higher time resolution measurements than aircraft or free balloon platform, several problems are commonly encountered, including engineering difficulties associated with a 1km long tethered cable, the error incurred by extrapolation to ≈ 65km of the potential measurement from low altitudes, and the influence of local meteorological conditions on the atmospheric electrical parameters, in particular convection currents and aerosol concentration.…”

“…Measurements of V I have also been made from tethered balloon platforms by Vonnegut et al (1973) (also implemented by Willet and Rust (1981)), Holzworth et al (1981), and Holzworth (1984). The maximum potential measured by Willett and Rust (1981) was 195kV, at a height of 5.3km above mean sea level, and 170kV at a height of 0.55km by Holzworth et al (1981).…”

Comment on “Hy‐wire measurements of atmospheric potential” by R. H. Holzworth

“…Since the tethered balloon was located along the coastline and operated in an airmass that had generally been advected from over the ocean, the aircraft and balloon data were obtained in the same region and type of airmass and would be comparable. The tethered balloon profiles labeled A through E were obtained in May 1981 while F was made in October 1980 [Holzworth, 1981b]. Since the aircraft measurements were made in August and the tethered balloon measurements were made in May and October, differences might have been due to seasonal changes in ionospheric potential.…”

“…Extrapolated to the ionosphere, the tethered balloon potential profiles would generally give ionospheric potentials on the order of 500 kV, which is well beyond the values measured in any other program. Holzworth [1981aHolzworth [ , 1981bHolzworth [ , 1982Holzworth [ , 1984 The factors that cause atmospheric electrical noise come together in such a way as to make a coastal region particularly unsuitable for global circuit measurements. In air masses within a few degrees of saturation there are large abrupt changes in the aerosol number density spectrum which alter conductivity and thus potential gradient.…”