Thunderstorm Electrification: Asymmetric Charging, Ice Crystal/Graupel Charging and Anomalous Zones
Charge transfer between colliding ice crystals and graupel pellets can lead to thunderstorm electrification. Many laboratory studies have shown how the sign of charge is influenced by temperature and cloud water content. The magnitude is principally influenced by impact speed and particle size. Recent work has shown that the effective supersaturation in the cloud has an important control over charging and that differences between various laboratory cloud simulations can lead to different results as a result of supersaturation differences. In particular, the supersaturation controls the diffusional growth rates of the colliding particles and the various charging results are found to be consistent with the hypothesis that the ice surface growing faster by vapour diffusion charges positively. Three issues are covered here: positive charging tends to have higher values than negative charging; certain experimental (anomalous) results are not consistent throughout all experimental studies reported;and the need for the presence of droplets to rime the graupel during significant charge transfer events is questioned. All these issues may be resolved in terms of cloud supersaturation and the relative rates of growth of the colliding ice surfaces.
Clive Saunders Christopher Emersic
Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences,The Universi Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences,The Universi
国际会议
第13届国际大气电学会议(The 13th International Conference on Atmospheric Electricity)
北京
英文
2007-08-13（万方平台首次上网日期，不代表论文的发表时间）