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  • Author or Editor: Eldo E. Ávila x
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Eldo E. Avila, Guillermo G. Aguirre Varela, and Giorgio M. Caranti

Abstract

Charge transfer between colliding ice particles is measured using a wind tunnel inside a cold room. A cylinder growing by riming in a wind tunnel was used as a target for collisions between 5 and 6 m s−1 with ice spheres of 100-µm diameter. The target temperature was adjusted to simulate different liquid water concentrations. As the target temperature increased, for air temperatures below −18°C, initial positive target charging reversed sign to negative; with a further temperature increase the charging reversed sign again. These measurements, which are relevant to thunderstorm electrification, were carried out with and without riming and results are compared with other works. A novel approach is presented here suggesting a new pair of variables describing the charging.

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Timothy J. Lang, Stéphane Pédeboy, William Rison, Randall S. Cerveny, Joan Montanyà, Serge Chauzy, Donald R. MacGorman, Ronald L. Holle, Eldo E. Ávila, Yijun Zhang, Gregory Carbin, Edward R. Mansell, Yuriy Kuleshov, Thomas C. Peterson, Manola Brunet, Fatima Driouech, and Daniel S. Krahenbuhl

Abstract

A World Meteorological Organization weather and climate extremes committee has judged that the world’s longest reported distance for a single lightning flash occurred with a horizontal distance of 321 km (199.5 mi) over Oklahoma in 2007, while the world’s longest reported duration for a single lightning flash is an event that lasted continuously for 7.74 s over southern France in 2012. In addition, the committee has unanimously recommended amendment of the AMS Glossary of Meteorology definition of lightning discharge as a “series of electrical processes taking place within 1 s” by removing the phrase “within 1 s” and replacing it with “continuously.” Validation of these new world extremes 1) demonstrates the recent and ongoing dramatic augmentations and improvements to regional lightning detection and measurement networks, 2) provides reinforcement regarding the dangers of lightning, and 3) provides new information for lightning engineering concerns.

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