摘要
闪电双向先导原理的提出及观测验证是闪电物理研究近几十年最重要的进展之一,而正、负先导及流光的极性不对称性及传输的持续、间歇性,是理解闪电各种过程物理机制的关键.本文对闪电双向先导的概念及进展进行了总结和讨论,重点强调了正、负先导流光传输机制特别是门限电场的不对称性,阐述了正先导传输的连续性及其在闪电始发、负先导的空间先导形成、不稳定先导通道中的反冲先导建立等过程中独特的启动作用.
A lightning discharge in a thundercloud usually starts with a locally breakdown process（preliminary breakdown）followed by a widely extending leader process. In the early 1960 s, from the view of fundamental electrostatics [Kasemir H W 1960 J. Geophys. Res. 65 1873] suggested that the lightning leader is initiated by an electrodeless discharge with a zero-net-charge conductive channel extending bidirectionally in the ambient electric field of the thundercloud, i.e.the bidirectional leader theory. However, the bidirectional leader theory has just been recognized by lightning researchers since the late 1980 s, when airplane [Mazur V 1989 J. Geophys. Res. 94 3326] and rocket-triggered lightning experiments have proven that the bidirectional leader theory provides the best common physical basis for explaining a variety of lightning processes. Nevertheless, challenges still remain in other properties of the bidirectional leader theory, such as the polarity asymmetry, the sustainability, instability and restrike of a leader channel, which are all the key concerns of lightning researches.In the present paper, we first briefly review the concept and development of the bidirectional leader theory and its appearances in various lightning processes, especially in the negative stepped leader and recoil leader process. By reviewing a variety of field observation data of inception thresholds and propagation properties of long gap spark discharges,we put forward and emphasize an alternative polarity asymmetry of the lightning leader： the polarity asymmetry of continuity, i.e., the continuity of positive leader and the intermittency of negative leader. Based on the detailed discussion,we then argue that the stepwise positive leader may be restrikes due to temporary instability of a continuous positive leader, while the intermittency of negative leader manifests not only a relatively regular stepped leader but also a more erratic negative recoil leader. We further propose that the positive leader-streamer may play a unique r
作者
苟学强
张义军
李亚珺
陈明理
Gou Xue-Qiang;Zhang Yi-Jun;Li Ya-Jun;Chen Ming-Li(College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou 730070,China;Institute of Atmospheric Sciences,Department of Atmospheric and Oceanic Sciences,Fudan University,Shanghai 200438,China;Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences,Lanzhou 730000,China;Department of Building Services Engineering,The Hong Kong Polytechnic University,Hong Kong,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第20期400-410,共11页
Acta Physica Sinica
基金
国家自然科学基金重大研究计划(批准号:91537209)
香港特别行政区研究拨款委员会(批准号:PolyU152139/15E)资助的课题~~
关键词
闪电
双向先导
极性不对称
间歇性
lightning
bidirectional leader
polarity asymmetry
intermittency
