A study of the use of atmospheric‐electric measurements in fog forecasting

Serbu, G. P.; Trent, Eva Mae

doi:10.1029/tr039i006p01034

Cited by 17 publications

(8 citation statements)

References 5 publications

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“…During this period, the current level decreased to a minimum between 00:30 and 01:30 UT. This observation agrees with the results reported in earlier works by Dolezalek (1963) and Serbu and Trent (1958). Prospero (1984) showed that before fog visibly forms, the growing droplets capture atmospheric ions, thereby increasing the resistivity of air and leading to a rapid reduction in the current density.…”

Section: Fogsupporting

confidence: 83%

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

Panneerselvam¹,

Nair²,

Selvaraj³

et al. 2007

Earth Planet Sp

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Observations of atmospheric Maxwell current from the low-latitude continental station, Tirunelveli (8.7 • N, 77.8• E), over a period of 8 years are presented in this study. The horizontal long-wire antenna is used as a sensor for picking up charges from the atmosphere. The objectives of the present work have been to understand the antenna system in response to different meteorological conditions and on fairweather days. We define a fairweather day as a day when there is no snowfall/rainfall at the measuring site, when there are high clouds less than 3 octas throughout the day, and when the wind speed is less than 10 m s −1 . A sunrise effect is observed in the measured Maxwell current during fairweather days in all seasons. The measured current exhibits an increase that commences about 30 min before sunrise and lasts for nearly 1.5 h. The sunrise effect is found to be inhibited on days when there is pre-dawn convection and during the presence of rain, haze, or cloud cover. Barring the sunrise effect, the rest of the variations on fairweather day appear to follow a trend typical of the Carnegie curve. On clear cloudless conditions, reasonably good data are obtained during equinox and winter months but not in summer when strong winds associated with the onset of the southwest monsoon make the measurement of Maxwell current difficult and limited data are available.

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Section: Fogsupporting

confidence: 83%

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

Panneerselvam¹,

Nair²,

Selvaraj³

et al. 2007

Earth Planet Sp

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“…The discontinuity in conductivity that causes screening layers may not occur at the visible cloud boundaries. For example, conductivity is usually reduced more than 30 min before fog is visible (e.g., Serbu and Trent 1958;Dolezalek 1963). Furthermore, Byrne et al (1989) found evidence that screening-layer charge can descend with distance outward in the anvil as hydrometeors fall.…”

Section: B Anvil Flashes In Screening-layer Chargementioning

confidence: 96%

Lightning in the Anvils of Supercell Thunderstorms

Weiss

MacGorman

Calhoun

2012

Monthly Weather Review

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This study uses data from the Oklahoma Lightning Mapping Array (OK-LMA), the National Lightning Detection Network, and the Norman, Oklahoma (KOUN), prototype Weather Surveillance Radar-1988 Doppler (WSR-88D) radar to examine the evolution and structure of lightning in the anvils of supercell storms as they relate to storm dynamics and microphysics. Several supercell storms within the domain of the OK-LMA were examined to determine whether they had lightning in the anvil region, and if so, the time and location of the initiation of the anvil flashes were determined. Every warm-season supercell storm had some flashes that were initiated in or near the stronger reflectivities of the parent storm and propagated 40-70 km downstream to penetrate well into the anvil. Some supercell storms also had flashes that were initiated within the anvil itself, 40-100 km beyond the closest 30-dBZ contour of the storm. These flashes were typically initiated in one of three locations: 1) coincident with a local reflectivity maximum, 2) between the uppermost storm charge and a screening-layer charge of opposite polarity near the cloud boundary, or 3) in a region in which the anvils from two adjoining storms intersected. In some storms, anvil flashes struck ground beneath a reflectivity maximum in which reflectivity $20 dBZ had extended below the 08C isotherm, possibly leading to the formation of embedded convection. This relationship may be useful for identifying regions in which there is a heightened risk for cloud-to-ground strikes beneath anvil clouds. In one storm, however, anvil lightning struck ground even though this reflectivity signature was absent.

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“…Occasionally, when drizzle occurred, the current reading showed a small negative (opposite to normal) value (Figure 3). These observations agree with those reported by Serbu and Trent [1958] and Dolezalek [1962]. They observed a considerable increase in the electric field and a decrease in conduction current 1-2 hours before the onset of the fog and reverse changes before the dissipation of the fog.…”

Section: As Was Noted By Israel [1973] the Diurnal And Seasonal Varimentioning

confidence: 99%

Direct measurements of the atmospheric conduction current

Burke

Few

1978

J. Geophys. Res.

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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).

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A study of the use of atmospheric‐electric measurements in fog forecasting

Cited by 17 publications

References 5 publications

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

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

Lightning in the Anvils of Supercell Thunderstorms

Direct measurements of the atmospheric conduction current

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