What is it about?
As early as 1955, Pierce has presented that the lightning return stroke’s channel consisted of a thin, hot inner core surrounded by a corona. Many theoretical studies on the lightning corona sheaths have involved the lightning channel core. Fortunately, in the summer of 2016 at Datong, Qinghai, China; a visible channel core of a natural cloud-to-ground lightning was clearly recorded by a high-speed camera on the first image of the first return stroke. To the best of our knowledge, such an image has never been reported before. The lightning channel core is significant for researching the lightning channel structures and their corresponding dynamic characteristics. In addition, a weak luminous region between the channel core outer edge and the peripheral luminous channel was analyzed, and the spectral characteristics confirmed that the discharge was the strongest at the connection point. This will be of interest not only to the lightning physics scientific community but also to all those who want to know about lightning.
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Why is it important?
The channel core of natural negative cloud-to-ground lightning was recorded using a high-speed slitless spectrograph, which confirms the corona sheath model of the lightning channel. By analyzing the channel spectra and images at different stages, it is corroborated that the ionic lines in spectra are mainly due to the channel core. Based on the luminescence and spectral characteristics, the connection point of the downward moving leader and the upward connecting leader was located, and it is concluded that the current is the highest at the connection point. Above all, it is discovered that there is no obvious channel core below the connection point, which means that the current is transmitted over the whole channel cross section. This feature is an important basis for investigating the lightning connection process and the physical mechanism of a lightning strike.
Perspectives
This paper will be of interest not only to the lightning physics scientific community but also to all those who want to know about lightning.
Guorong Liu
Lanzhou University of Technology
Read the Original
This page is a summary of: A visible channel core and the channel structure below the connection point for natural cloud-to-ground lightning, Frontiers in Human Neuroscience, August 2019, American Institute of Physics,
DOI: 10.1063/1.5111845.
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