Electric field measurements within a severe thunderstorm anvil

Abstract

The anvil cloud of a supercell severe storm in central Oklahoma was penetrated by two free balloons carrying corona probes to measure electric fields. The two balloons passed through the portion of the anvil upstream of the precipitation core and provided information on the charge concentrations and vertical thicknesses of the electric charge regions within the cloud. The trajectories of the balloons relative to the storm were horizontally separated by approximately 35 km, providing information on the horizontal extent of the charge regions. Contrary to the general assumption that anvil interiors are positively charged, the results of the two flights indicate that extensive regions of both net positive and negative charge were present in the interior of the anvil. Net positive charge was observed in both balloon flights in the lower portion of the anvil interior. The vertical thickness of the positive charge region was measured in each flight to be 1.6 and 2.3 km, respectively. A charge concentration of +0.2 nC m−3 was estimated from one of the flights. Net negative charge was observed by both balloons in the upper portion of the anvil interior. The vertical thickness and charge concentration of the negative charge region were estimated from one flight to be 3.2 km and −0.1 nC m−3, respectively. Screening charge layers were identified at the upper and lower boundaries of the anvil, with a typical thickness of a few hundred meters, which is an order of magnitude greater than that calculated in a previous model. We propose a conceptual model of the development of anvil charge regions based on our balloon measurements and previous observations of anvil dynamics. In this model we suggest that the thicknesses of the anvil screening layers increase with distance from the precipitation core of the storm owing to turbulent mixing near the cloud boundaries and differences in the sedimentation rates of the cloud particles. Negative charge in the upper portion of the anvil interior results from the expansion of the upper negative screening layer into lower levels of the anvil cloud.

On the role of electromagnetic phenomena in some atmospheric processes

“…At the same time, experimental observations indicate the presence of extended charged regions in the TC structure and the presence of strong electromagnetic regions in the TC and tornado regions (Black and Hallet, 1999;Vonnegut, 1960;Ziegler and MacGorman, 1994;Winn et al, 2000;Krasilnikov 1997;Chalmers, 1967;Williams, 1989;Marshall and Rust, 1995;Byrne et al, 1989). In all similar phenomena one can see the generation mechanism of charged particles by friction (one of the possible mechanisms).…”

“…The multilayer electrical structures of a cloud cover are observed within thunderstorms (Marshall and Rust, 1995;Byrne et al, 1989). Thus, in the Wayene experiment the electrical structure of 8 charge layers was recorded, the layers being located bottom up (up to 14 km) in the following order: + − + − + − +−.…”

“…The correlation was found between the increase of electric field in the atmosphere and the growth of concentrations of aerosols. The influence of aerosols on weather and climate is a separate subject which is beyond the scope of this article (Budyko, 1974;Lee and Penner, 2010;Lohmann and Feichter, 2005). The ions, in turn, influence atmospheric processes via (1) charge-dependent chemical reactions, (2) forming of droplets and ice pieces during condensation on nuclei, and (3) the currents in the global electric circuit (the maximum of charged particles' fluxes and ion production in the atmosphere is located at altitudes of 12-17 km).…”

Prevention of destructive tropical and extratropical storms, hurricanes, tornadoes, dangerous thunderstorms, and catastrophic floods

“…However, numerous studies of the third aspect show that the electric structure of a mature thundercloud ( Fig. 1) is the tripole one (Chalmers, 1967;Williams, 1989;Byrne et al, 1989). At an altitude of about 6 km (according to different authors, the range is from 3 to 8 km; Chalmers, 1967) above the Earth's surface, where the air temperature is about −15 • C, there is the center of the negatively charged layer.…”

Electromagnetohydrodynamic nature of tropical cyclones, hurricanes, and tornadoes

“…As for the first two aspects, in spite of extensive and prolonged studies [e.g., Workman and ReynoMs, 1950;Vonnegut, 1953;Chalmers, 1967] there is till now no common viewpoint both with respect to the mechanism of electric charge formation during cloud forming and with respect to the process of their separation. However, numerous studies of the third aspect showed that the electric structure of mature powerful thunderstorms is the tripole one [Chalmers, 1967;Williams, 1989;Byrne et al, 1989]. …”