Activation of Abundant Recoil Leaders and Their Promotion Effect on the Negative‐End Breakdown in an Intracloud Lightning Flash

Jiang, Rubin; Yuan, Shanfeng; Qie, Xiushu; Liu, Mingyuan; Wang, Dongfang

doi:10.1029/2021gl096846

Cited by 16 publications

(17 citation statements)

References 38 publications

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“…Bright positive leaders have been observed in high speed video in other studies, but the reported leader speed is typically one to two orders of magnitude higher (10 5 –10 6 m/s) (Campos et al., 2014; Kong et al., 2015; Saba et al., 2008), suggesting the reported optical positive leaders develop under different circumstances as compared to the slow in‐cloud development as presented in this paper. Some studies have reported optical observations with evidence of dim or dark positive leaders extending on the order of 10 4 m/s (Jiang et al., 2022; Kong et al., 2008; Wang et al., 2019).…”

Section: Discussionmentioning

confidence: 99%

Insights Into Lightning K‐Leader Initiation and Development From Three Dimensional Broadband Interferometric Observations

Jensen,

Shao,

Sonnenfeld

2023

JGR Atmospheres

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We report detailed observations of K‐leaders and the activity between them with the three‐dimensional Broadband Interferometric Mapping and Polarization system (BIMAP‐3D) at Los Alamos National Laboratory. It is found that K‐leaders have a general propagation trend of initial acceleration and then gradual deceleration, and the corresponding very high frequency (VHF) radiation power is exponentially correlated with the leader speed. Based on the 3D development and simultaneous electric field change measurement, some simple K‐leaders can be modeled with time‐evolving point charges at the propagating leader tip and at the stationary origin. We found that the charge magnitude increases during the initial acceleration stage and stays relatively constant for the rest of the development. K‐leaders are observed to interact with other branches; the branches affect the leader's propagation speed, and may affect the charge transfer. After the occurrence of a K‐leader, VHF emissions are quenched for several milliseconds. VHF sources then reappear in an impulsive and scattered manner as “twinkling,” and these sources are found not uniquely on the so‐called needles, but also on the main channel. These twinkling sources start near the apparent positive leader tip, and extend back toward the direction of the flash origin at about 105 m/s, while the apparent positive tip continues to extend forward at about 104 m/s. The twinkling extending toward the direction of flash origin appears to initiate the following K‐leader, although it may be interrupted by a K‐leader along a different branch, or simply die out without more K‐leader activity.

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Section: Discussionmentioning

confidence: 99%

Insights Into Lightning K‐Leader Initiation and Development From Three Dimensional Broadband Interferometric Observations

Jensen,

Shao,

Sonnenfeld

2023

JGR Atmospheres

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“…Jiang et al. (2022) combined optical images and mapping of VHF radiation sources, and hypothesized that long dart leaders (referred to as recoil leaders in that work) activated negative breakdown at the opposite end of a corresponding channel network at the time when the regular pulse trains were observed.…”

Section: Introductionmentioning

confidence: 99%

“…Using an array of 12 electric field antennas, Shi et al (2020) found that a majority of pulse trains propagated through the main negative charge region. Jiang et al (2022) combined optical images and mapping of VHF radiation sources, and hypothesized that long dart leaders (referred to as recoil leaders in that work) activated negative breakdown at the opposite end of a corresponding channel network at the time when the regular pulse trains were observed.…”

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confidence: 99%

A Strong Pulsing Nature of Negative Intracloud Dart Leaders Accompanied by Regular Trains of Microsecond‐Scale Pulses

Kolmašová

Scholten²,

Santolı́k

et al. 2023

Geophysical Research Letters

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Lightning processes often occur in repeating patterns with rates ranging from units of microseconds to fractions of a second. Among these processes, the most explored ones are parts of lightning flashes, which take place below the thundercloud, as the Return Strokes (RSs), stepped leaders, dart leaders, dart-stepped leaders, and M-components in cloud-to-ground (CG) discharges, which have been investigated for many decades. Both optical and electromagnetic records confirm that individual lightning strokes within multi-stroke flashes are typically separated by several tens of milliseconds (Poelman et al., 2021). The repetition rate of stepped leader pulses is about several tens of kHz (Lu et al., 2008) and the dart-stepped leader pulses occur in a succession, which is as short as several microseconds (Jiang et al., 2014). The incloud processes, as lightning initiation or propagation of intracloud (IC) leaders, are usually not visible for high-speed cameras. When exploring them, we have to rely on electromagnetic measurements. Sequences of initial (or preliminary) breakdown (IB) pulses are believed to accompany the initiation of majority of CG and IC discharges in their electromagnetic records (Marshall Abstract We report the first observations of negative intracloud (IC) dart-stepped leaders accompanied by regular trains of microsecond-scale pulses, simultaneously detected by shielded broadband magnetic loop antennas and the radio telescope Low Frequency Array (LOFAR). Four investigated pulse trains occurred during complicated IC flashes on 18 June 2021, when heavy thunderstorms hit the Netherlands. The pulses within the trains are unipolar, a few microseconds wide, and with an average inter-pulse interval of 5-7 μs. The broadband pulses perfectly match energetic, regularly distributed, and relatively isolated bursts of very high frequency sources localized by LOFAR. All trains were generated by negative dart-stepped leaders propagating at a lower speed than usual dart leaders. They followed channels of previous leaders occurring within the same flash several tens of milliseconds before the reported observations. The physical mechanism remains unclear as to why we observe dart-stepped leaders, which show mostly regular stepping, emitting energetic microsecond-scale pulses. Plain Language SummaryLightning phenomena inside thunderclouds can be explored using their electromagnetic radiation. To study these processes at small temporal and spatial scales, we combine broadband magnetic loop antennas with the Low Frequency Array (LOFAR) radio telescope. Measurements of broadband antennas acquired during a severe Dutch thunderstorm showed pulse sequences composed of tens microsecond-scale unipolar pulses, which were surprisingly regularly distributed. Such regular pulse trains have been rarely reported from previous observations. When we thoroughly lined up the timestamps of both simultaneously measuring observational systems, we found that the regular broadband pulses perfectly match with localized isolated bursts of ener...

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“…The positive ends of these BLs retracted the decaying channel of the preceding attempted leader at higher speeds than the negative ends which propagated downwards along the remnants of the channel created by the previous stroke or initiate a continuous current. Jiang et al 21 reported an intracloud lightning flash where a positive leader from the cloud induced a bidirectional luminous segment ahead of the leader tip. It follows that various reasons contribute to the formation of bidirectional leaders.…”

Section: Introductionmentioning

confidence: 99%

Three types of bidirectional leader development in triggered lightning flashes

Wang

et al. 2023

Sci Rep

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Eight cases of bidirectional leader (BL) development in artificially triggered lightning flashes are reported with synchronous high-speed camera images and electric field signals. Based on optical progressing characteristics, the eight cases can be divided into three types: a reflection type, a discontinuity type, and an inducement type. For the reflection type, the tail of a dart leader may begin to extend backward when the leader’s head reaches a branch point, or the top of the exploded triggering wire. For the discontinuity type, the initiation of a bidirectional leader below a decayed attempted leader may occur more than once preceding one return stroke. For the inducement type, the approach of another leader with the same polarity will turn a dart leader into a bidirectional leader. The reflection type and inducement type are first observed here. Two cases of the discontinuity type are observed, and both are multiple-bidirectional leaders observed for the first time. For the reflection type and inducement type, there are fluctuations in the electric field related to the BL development. The dissipation of the downward leader slows down the negative increase of the electric field. Once the BL development starts, the downward negative end of the BL moves towards the ground with the E-field negatively increasing. For the discontinuity type, the close electric field result shows no fluctuations. The BL development has a much longer duration than the other two BL types.

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Activation of Abundant Recoil Leaders and Their Promotion Effect on the Negative‐End Breakdown in an Intracloud Lightning Flash

Cited by 16 publications

References 38 publications

Insights Into Lightning K‐Leader Initiation and Development From Three Dimensional Broadband Interferometric Observations

Insights Into Lightning K‐Leader Initiation and Development From Three Dimensional Broadband Interferometric Observations

A Strong Pulsing Nature of Negative Intracloud Dart Leaders Accompanied by Regular Trains of Microsecond‐Scale Pulses

Three types of bidirectional leader development in triggered lightning flashes

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