Separate luminous structures leading positive leader steps

Huang, Surong; Chen, Weijiang; Fu, Zhuojia; Fu, Yufei; Xiang, Nianwen; Qiu, Xinjie; Shi, Wenzhen; Cheng, Daizhan; Zhang, Zhiyuan

doi:10.1038/s41467-022-31409-x

Cited by 11 publications

(6 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It can be inferred that positive leaders initiated by different means could exhibit a stepwise pattern under favorable situation. For example, the laboratory experiments of Huang et al (2022) indicate that at high environmental humidity, the propagation of positive leaders will exhibit a stepped fashion.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Low Frequency Magnetic Field Observations of Natural Positive Leaders Featuring Stepwise Propagation

Wang,

Lu,

et al. 2023

Geophysical Research Letters

View full text Add to dashboard Cite

We examine the low‐frequency (LF) magnetic pulses recorded for the positive leader in two natural lightning flashes as recorded on the high‐speed video camera. The captured positive leader in both cases propagated in a stepwise manner at least over several milliseconds according to the concurrent sequence of LF magnetic pulses. By comparing with previous studies on positive leaders under different situations, the average inter‐pulse intervals (11.7 and 20.3 μs, respectively) obtained for our natural cases are shorter than that of upward positive leaders in rocket‐triggered (typically >25 μs) and tower‐initiated lightning (62 μs in one case). Hence, the stepwise propagation of positive leaders in natural lightning is likely more frequent than that in object‐induced lightning, reflecting a possible influence of ambient electric field and other meteorological factors on the stepwise feature of positive leader. The stepwise extension might be common for positive leaders developing in various scenarios.

show abstract

Section: Discussionmentioning

confidence: 99%

“…For example, the laboratory experiments of Huang et al. (2022) indicate that at high environmental humidity, the propagation of positive leaders will exhibit a stepped fashion.…”

Section: Discussionmentioning

confidence: 99%

Low Frequency Magnetic Field Observations of Natural Positive Leaders Featuring Stepwise Propagation

Wang,

Lu,

et al. 2023

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…(2020). There is a growing body of evidence that positive leaders in long sparks and lightning can also involve space leaders formed inside or near the streamer zone extending from the leader tip (see Huang, Chen, Fu, Fu, et al., 2022; Huang, Chen, Fu, Xiang, et al., 2022; Huang et al., 2021; Kostinskiy et al., 2018). Space leaders were also observed inside the common streamer zone of the breakthrough phase of the lightning (Biagi et al., 2009; Gamerota et al., 2015) and long spark (Fu et al., 2022) attachment process.…”

Section: Discussion and Summarymentioning

confidence: 99%

Unusual Plasma Formations Produced by Positive Streamers Entering the Cloud of Negatively Charged Water Droplets

et al. 2022

View full text Add to dashboard Cite

Kostinskiy et al. (2015aKostinskiy et al. ( , 2015b, using a framing camera operating in the infrared (IR) range of 2.5-5.5 μm, have discovered a new class of electric discharges within artificial clouds of charged water droplets with typical radii of 0.3-0.5 μm (considerably smaller than the IR wavelengths) and termed those discharges unusual plasma formations (UPFs). In the IR images, some UPF segments had similar or even greater brightness than the positive upward leader channel imaged in the same frame, suggesting that the temperature of those UPF segments is comparable to that of upward positive leaders. The upward positive leaders were preceded by initial positive corona streamer bursts, both originating from a small sphere on the grounded plane and propagating over 1 m or so toward the negatively charged cloud. Hundreds of IR images of UPFs were obtained and examined, with many examples being presented by Kostinskiy et al. (2015aKostinskiy et al. ( , 2015b, but only a few UPFs were recorded in the visible range. This is the case because UPFs occur primarily inside the cloud where visible light (whose wavelengths are comparable to the water droplet size) experiences strong scattering.The goal of this work was to examine the genesis of UPFs; that is, to gain new insights into the dynamics of UPFs and draw some inferences about the mechanism of their initiation and development. This was impossible with the IR records, for which the exposure time was as large as 2-3 ms. We supplemented the experimental setup used by Kostinskiy et al. (2015aKostinskiy et al. ( , 2015b) by microwave diagnostics (Bogatov et al., 2020) and acquired additional data, including good visible-range images of two UPFs which occurred outside (near the edge of) the cloud. In contrast to the IR camera, the visible-range camera operated with microsecond-scale exposure times, which was sufficient for resolving the UPF occurrence context. We also recorded the electric current at the grounded sphere and the time of luminosity onset in the cloud (with a photomultiplier tube). Our overall data set is unique, and the results constitute the first experimental evidence of a scenario in which UPFs can occur.In this article, we use the term "long streamers" in referring to streamers that have essentially lost their galvanic (electrical) connection with their origin. Streamer is a cold plasma formation composed of a brighter head and a much fainter tail. Part of the tail, which is closer to the head, contains a significant number of free electrons and therefore is conducting. The characteristic length of the conducting part of streamer tail can be roughly estimated based on the speed of movement of streamer head 𝐴𝐴 𝐴𝐴str and the characteristic electron loss time scale 𝐴𝐴 𝐴𝐴𝑎𝑎 due to attachment and recombination, which is of the order of tens of nanoseconds (e.g., Francisco et al., 2021, Figure

show abstract

“…The research on positive leader has been primarily focused on investigating fundamental physical processes, initiation meteorological conditions, velocity‐current relationships, and analysis of two‐dimensional (2‐D) velocity (Kitagawa & Michimoto, 1994; Nag & Rakov, 2009; Saba et al., 2009; Yuan et al., 2017). Extensive studies have been conducted to explore leader stepping, cloud charge configurations, electric field ( E ‐field) waveforms, multiplicity and transferred charge (Qie et al., 2005; Lu et al., 2009, 2016; Saba et al., 2010; S. Huang et al., 2022; Wang et al., 2023). Nag and Rakov (2012) reported on the investigation of cloud charge configurations, identifying at least six configurations capable of producing downward positive lightning discharges.…”

Section: Introductionmentioning

confidence: 99%

Effects of Applied Voltage on Branching of Positive Leaders in Laboratory Long Sparks

Peng,

Li,

Pei

et al. 2024

Geophysical Research Letters

View full text Add to dashboard Cite

Positive leaders branch less frequently than negative counterpart, and the physical processes and properties of positive leader branching remain a mystery. We investigated 10 m laboratory discharges under four positive voltages using a high‐speed video camera. Positive leaders differ from negative leaders by either directly splitting or connecting with floating bidirectional leaders to form branching, and the number of leader branches shows a positive correlation with the applied voltage, that is, the branched channels increased from 1 to 4 when the voltage increased by a factor of 1.5. Grounding points are positioned beneath the electrode and are more concentrated with lower voltage. During the stable progression of the leader, there is a slight increase in its development speed as the applied voltage rises. When the voltage is increased by 70%, the average breakdown time decreases by 40%. These characteristics provide insights into the branching mechanism of positive leaders.

show abstract

Separate luminous structures leading positive leader steps

Cited by 11 publications

References 32 publications

Low Frequency Magnetic Field Observations of Natural Positive Leaders Featuring Stepwise Propagation

Low Frequency Magnetic Field Observations of Natural Positive Leaders Featuring Stepwise Propagation

Unusual Plasma Formations Produced by Positive Streamers Entering the Cloud of Negatively Charged Water Droplets

Effects of Applied Voltage on Branching of Positive Leaders in Laboratory Long Sparks

Contact Info

Product

Resources

About