Infrared and Visible-Range Optical Observations of Lightning at LOG (Lightning Observatory at Gainesville) and Associated Modeling

闪电是一种瞬时的高电流放电，通常在空气中数十千安培，闪光率为每秒数十到一百。闪电通道由电离气体或等离子体组成，其峰值温度通常为30，000 o K，约为太阳表面温度的五倍。每年，美国发生约2500万次云对地闪电放电，由于世纪的全球变暖，这一数字预计将增加约50%。对未受保护的物体或系统的雷击可能是灾难性的。闪电造成的死亡人数比任何其他与雷暴有关的危险，如龙卷风和洪水都多。闪电引发了许多森林火灾，超过30%的电力线路故障与闪电有关。在获资助的研究中，位于佛罗里达盖恩斯维尔的闪电观测站将首次采用一种新的高速红外分幅相机，结合现有的仪器，包括光学系统、在不同频率范围内工作的电场和磁场测量系统，以及X射线探测器，以获得前所未有的闪电过程视图。红外相机将允许对云层内的闪电通道进行成像，这些通道通常是可见光范围相机无法访问的。研究雷电通道的冷却过程和通道不同部位的热能输入。光学和相应的全球定位系统时间戳电磁场数据将被用来开发，第一次，一个非线性和非均匀的分布式电路模型，这将允许调查各种闪电过程，包括闪电附着到地面或接地物体的最后跳跃阶段，这还没有记录的自然闪电。这项资助的研究将进一步推进我们对闪电物理学及其影响的理解，对环境和气候变化研究以及减轻雷电对人类，结构和系统的危害具有重要意义。为了设计足够的防雷保护和制定雷电测试标准，需要对雷电附着过程有更好的了解。这个项目将涉及博士后和博士。研究生，以及国际合作，包括两名访问学者由他们的家乡大学和富布赖特学者支持。研究结果将纳入受欢迎的佛罗里达大学高级本科生/研究生课程“闪电”。“PI将继续参与高中科学教育和公众对雷电危害的认识。除了物理和动力气象学领域，该项目的成果将在其他学科，包括高能大气物理学，等离子体物理学，防雷和测试，以及雷电安全有用。

Lightning is a transient, high-current electric discharge of typically tens of kiloamperes in air with a flash rate in tens to a hundred per second. Lightning channel is composed of ionized gas or plasma, whose peak temperature is typically 30,000o K, about five times higher than the temperature of the surface of the Sun. Each year, some 25 million cloud-to-ground lightning discharges occur in the United States, and this number is expected to increase by about 50% due to global warming over the 21st century. A lightning strike to an unprotected object or system can be catastrophic. Lightning causes more fatalities than any other thunderstorm-related hazard, such as tornadoes and flooding. Lightning initiates many forest fires, and over 30% of all electric power line failures are lightning related. In the funded research, a new high-speed infrared (IR) framing camera will be employed for the first time at the Lightning Observatory in Gainesville, Florida for lightning observations in conjunction with the existing instrumentations, including the optical systems, electric and magnetic field measuring systems operating in different frequency ranges, and x-ray detector to obtain a view of lightning processes that has never been possible before. The IR camera will allow the imaging of lightning channels inside clouds that generally are not accessible to visible-range cameras. The lightning channel cooling process and the thermal energy input to different parts of the channel will be studied. The optical and corresponding GPS time-stamped electromagnetic field data will be used to develop, for the first time, a non-linear and non-uniform distributed-circuit model, which will allow the investigation of a variety of lightning processes, including the final-jump phase of lightning attachment to ground or grounded object, which has not been documented for natural lightning. This funded research will further advance our understanding of the physics of lightning and its effects with important implications for environmental and climate change research and for mitigation of lightning hazards to people, structures, and systems. An improved knowledge of lightning attachment process is needed for designing adequate protection against lightning and for developing lightning testing standards. This project will involve postdocs and Ph.D. graduate students, as well as international collaborations, including two visiting scholars supported by their home Universities and a Fulbright Scholar. The research findings will be incorporated in the popular University of Florida senior undergraduate/graduate course "Lightning." The PI will continue to engage with high-school science education and public awareness of lightning hazards. Besides the Physical and Dynamical Meteorology area, the results of the project will be useful in other disciplines, including high-energy atmospheric physics, plasma physics, lightning protection and testing, and lightning safety.