A Study of Preliminary Breakdown and Return Stroke Processes in High-Intensity Negative Lightning Discharges

Zhu, Yanan; Rakov, Vladimir A.; Tran, M. D.

doi:10.3390/atmos7100130

Cited by 21 publications

(27 citation statements)

References 24 publications

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“…Observe again that the average speed increases with increasing peak current, increasing streamer speed, and decreasing potential gradient. This result is in agreement with the results presented by Zhu et al [27], in which it was found that negative lightning flashes with faster stepped leaders tend to have higher first return stroke peak currents. However, it is the change in step length that influences the leader speed more than the time of formation.…”

Section: Stepped Leader Speedsupporting

confidence: 94%

“…Unfortunately, almost all the studies do not give the prospective return stroke peak current, and, for this reason, a direct comparison is impossible in the present study. The study also shows that the leader speed increases with increasing peak current and this tendency is also observed in the experimental data of Campos et al [26] and Zhu et al [27].…”

Section: Discussionsupporting

confidence: 82%

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Modeling the Stepping Process of Negative Lightning Stepped Leaders

Cooray

Arévalo

2017

Atmosphere

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A physical model based on the mechanism observed in experimental investigations is introduced to describe the formation of negative leader steps. Starting with a small length of a space leader located at the periphery of the negative streamer system of the stepped leader, the model simulates the growth and the subsequent formation of the leader step. Based on the model, the step length, the step forming time, and the propagation speed of stepped leaders as a function of the prospective return stroke peak current are estimated. The results show that the step length and the leader speed increase with increasing prospective return stroke current. The results also show that the speed of the stepped leader increases as it approaches the ground. For prospective return stroke currents in the range of 15 kA-60 kA, the step lengths lie within the range 5 m-100 m, the step forming times lie within the range 10 µs-250 µs, and the leader speed lies within the range 10 5 m/s −1.5 × 10 6 m/s. The results obtained are in reasonable agreement with the experimental observations.

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Section: Stepped Leader Speedsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 82%

Modeling the Stepping Process of Negative Lightning Stepped Leaders

Cooray

Arévalo

2017

Atmosphere

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“…Yoshida et al 30. reported upward positive leader (UPL) speeds of the order of 10 6 m/s (the corresponding leader current was of the order of kiloamperes) in rocket-triggered lightning, and Zhu et al 31. inferred similarly high speeds for exceptionally fast negative stepped leaders initiating return strokes with peak currents in excess of 100 kA in natural lightning.…”

Section: Discussionmentioning

confidence: 99%

Initiation and propagation of cloud-to-ground lightning observed with a high-speed video camera

Tran

Rakov

2016

Sci Rep

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Complete evolution of a lightning discharge, from its initiation at an altitude of about 4 km to its ground attachment, was optically observed for the first time at the Lightning Observatory in Gainesville, Florida. The discharge developed during the late stage of a cloud flash and was initiated in a decayed branch of the latter. The initial channel section was intermittently illuminated for over 100 ms, until a bidirectionally extending channel (leader) was formed. During the bidirectional leader extension, the negative end exhibited optical and radio-frequency electromagnetic features expected for negative cloud-to-ground strokes developing in virgin air, while the positive end most of the time appeared to be inactive or showed intermittent channel luminosity enhancements. The development of positive end involved an abrupt creation of a 1-km long, relatively straight branch with a streamer corona burst at its far end. This 1-km jump appeared to occur in virgin air at a remarkably high effective speed of the order of 106 m/s. The positive end of the bidirectional leader connected to another bidirectional leader to form a larger bidirectional leader, whose negative end attached to the ground and produced a 36-kA return stroke.

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“…Further, our results are also consistent with those of Zhu et al . [] who reported that the PB‐to‐RS interval was found to decrease with increasing RS peak currents for 3077 negative first strokes with peak currents equal to or greater than 50 kA occurring in an area including both land and ocean in and around Florida. In Figure d, the median leader duration for different ranges of NLDN‐estimated peak current ( I P bins) are shown for the five regions considered here.…”

Section: Duration Of Negative Stepped Leadermentioning

confidence: 99%

Negative first stroke leader characteristics in cloud‐to‐ground lightning over land and ocean

Nag

Cummins

2017

Geophysical Research Letters

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We examine downward leader characteristics for negative first return strokes, along with estimated first stroke peak currents, for lightning occurring over land and ocean reported by the U.S. National Lightning Detection Network (NLDN). For the first time, to the best of our knowledge, we report independent evidence that supports the observations by lightning locating systems of higher first stroke peak currents for lightning occurring over ocean than land. We analyzed lightning occurring in five circular regions, each with 50 km diameter. In western Florida, the median stepped‐leader duration was 17% shorter over ocean than over land and in eastern Florida the median durations were 21% and 39% shorter over two oceanic regions than over land. We infer that the shorter durations over ocean simply reflect the higher (25% in western Florida and 11%–16% in eastern Florida) oceanic return stroke peak currents reported by the NLDN. These findings indicate that the cloud charge structure for (at least some) oceanic storms are different than those for storms over land. The percentage of flashes that had at least one NLDN‐reported negative cloud pulse prior to the first negative cloud‐to‐ground stroke was found to be about the same over land and ocean. Using regression analysis, we found no evidence that the relationship between leader duration and first return stroke peak current is different over land and ocean.

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A Study of Preliminary Breakdown and Return Stroke Processes in High-Intensity Negative Lightning Discharges

Cited by 21 publications

References 24 publications

Modeling the Stepping Process of Negative Lightning Stepped Leaders

Modeling the Stepping Process of Negative Lightning Stepped Leaders

Initiation and propagation of cloud-to-ground lightning observed with a high-speed video camera

Negative first stroke leader characteristics in cloud‐to‐ground lightning over land and ocean

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