Initial leader velocities during intracloud lightning: Possible evidence for a runaway breakdown effect

Behnke, S. A.; Thomas, Ronald J.; Krehbiel, P. R.; Rison, W.

doi:10.1029/2004jd005312

Cited by 54 publications

(75 citation statements)

References 30 publications

(44 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We simulate the initial stages of the lightning tree development, where it can be assumed that the discharge is predominantly vertical and has a length scale, ℓ 0 , between tens of meters up to ∼2 km. Beyond this length the leader network starts to branch horizontally inside the thunderstorm charge centers [e.g., Rison et al , ; Thomas et al , ; Behnke et al , ]. Winn et al [, Figure 9] used electric field change data recorded at distances of ∼200 m from the lightning channels combined with VHF mapping to estimate leader step lengths of ∼50–600 m. Marshall et al [, Table 2] used an array of fast antennas to estimate vertical displacements in IBP bursts of ∼200–1800 m. For this reason, we assume that ℓ step can vary between tens of meters up to ∼1.5 km.…”

Section: Model Formulationmentioning

confidence: 99%

Physical mechanism of initial breakdown pulses and narrow bipolar events in lightning discharges

Silva

Pasko

2015

JGR Atmospheres

View full text Add to dashboard Cite

To date the true nature of initial breakdown pulses (IBPs) and narrow bipolar events (NBEs) in lightning discharges remains a mystery. Recent experimental evidence has correlated IBPs to the initial development of lightning leaders inside the thundercloud. NBE wideband waveforms resemble classic IBPs in both amplitude and duration. Most NBEs are quite peculiar in the sense that very frequently they occur in isolation from other lightning processes. The remaining fraction, 16% of positive polarity NBEs, according to Wu et al. (2014), happens as the first event in an otherwise regular intracloud lightning discharge. These authors point out that the initiator type of NBEs has no difference with other NBEs that did not start lightning, except for the fact that they occur deeper inside the thunderstorm (i.e., at lower altitudes). In this paper, we propose a new physical mechanism to explain the source of both IBPs and NBEs. We propose that IBPs and NBEs are the electromagnetic transients associated with the sudden (i.e., stepwise) elongation of the initial negative leader extremity in the thunderstorm electric field. To demonstrate our hypothesis a novel computational/numerical model of the bidirectional lightning leader tree is developed, consisting of a generalization of electrostatic and transmission line approximations found in the literature. Finally, we show how the IBP and NBE waveform characteristics directly reflect the properties of the bidirectional lightning leader (such as step length, for example) and amplitude of the thunderstorm electric field.

show abstract

Section: Model Formulationmentioning

confidence: 99%

Physical mechanism of initial breakdown pulses and narrow bipolar events in lightning discharges

Silva

Pasko

2015

JGR Atmospheres

View full text Add to dashboard Cite

show abstract

“…The model of Mansell et al [2002] may temporarily put one end of the tree on hold in case any deviation from neutrality arises. The models of Mazur and Ruhnke [1998], Bazelyan and Raizer [2000], Behnke et al [2005], and Riousset et al [2007] shift the potential of the leader such that its net induced charge is zero. The potential of the leader is the average ambient potential over the leader length [Bazelyan and Raizer, 2000].…”

Section: The Effect Of Negative and Positive Leader Speed Difference mentioning

confidence: 99%

“…As an essential element of the graph, our version uses dashed lines to provide a reference for slopes of leader traces corresponding to different 2-D radial speeds relative to the chosen point (note that Behnke et al [2005] used separate t-x and t-y plots to determine leader speeds). The slope of traces of sources is a proxy for leader propagation velocity, useful for qualitative purposes and rough estimates (which suffices for this study), but we do recognize that it is not the true 3-D leader speed.…”

Section: Der Velde and Montanyà: Asymmetries Of Leaders In Lightningmentioning

confidence: 99%

“…The key concepts of bidirectional leader theory are that shortly after initiation, positive and negative leaders are two ends of one "tree" which move simultaneously into opposite polarity charges while maintaining their original potential by balancing the positive and negative charges on the leader channel (zero net charge). Mazur and Ruhnke [1998] and Behnke et al [2005] explain that the potential of the conducting channel will adjust in order to maintain zero net charge induced on the channel by the cloud charge regions ("potential wells," refer to Figure 5 in both works). This concept allows a prediction of the behavior of a simple lightning flash by comparing the potential of the leader to the cloud potential profile.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Asymmetries in bidirectional leader development of lightning flashes

2013

View full text Add to dashboard Cite

Lightning flashes develop as a bidirectional tree, with a negative and a positive end propagating simultaneously into cloud charges of the opposite polarity. In recent years, this process has been modeled assuming that the bidirectional channel remains a zero‐net‐charge perfect conductor starting at the electric potential of its initial location. So far, both leader ends were treated identically. We summarize characteristics of bidirectional leader development of various lightning flashes registered by the Ebro 3‐D Lightning Mapping Array at the east coast of Spain, supplemented by high‐speed camera records. In order to follow the horizontal development of positive and negative leaders over time, a time‐distance‐altitude graph was designed, using the flash origin or a cloud‐to‐ground stroke as reference. The examples confirm that negative and positive leaders propagate at characteristic horizontal speeds (105 and 2 · 104 m s−1). The positive leader's low apparent speed corresponds to the phase when recoil processes are active. Very fast negative leaders (up to 8 · 105 m s−1) are detected in association with positive cloud‐to‐ground strokes. Negative leaders respawn repeatedly from the origin or as a retrograde negative leader at the positive branch. Positive leaders remain propagating throughout the flash or until reaching ground. We show that the velocity difference shifts the potential of the leader, increasing the gradient with cloud charge at the positive end while reducing it at the negative end. The positive section lowers its potential through retrograde negative leaders, eventually making it possible to emit a new negative leader into the upper positive potential well.

show abstract

“…TGFs have been shown to occur at the beginning of intra-cloud lightning flashes, just after the initiation occurs. For instance, Behnke et al (2005) measured the initial leader velocities during intracloud lightning and Fig. 28 Simulation of a relativistic feedback discharge inside a thundercloud.…”

Section: The Tgf-lightning Connectionmentioning

confidence: 99%

High-Energy Atmospheric Physics: Terrestrial Gamma-Ray Flashes and Related Phenomena

2012

View full text Add to dashboard Cite

It is now well established that both thunderclouds and lightning routinely emit x-rays and gamma-rays. These emissions appear over wide timescales, ranging from submicrosecond bursts of x-rays associated with lightning leaders, to sub-millisecond bursts of gamma-rays seen in space called terrestrial gamma-ray flashes, to minute long glows from thunderclouds seen on the ground and in or near the cloud by aircraft and balloons. In particular, terrestrial gamma-ray flashes (TGFs), which are thought to be emitted by thunderclouds, are so bright that they sometimes saturate detectors on spacecraft hundreds of kilometers away. These TGFs also generate energetic secondary electrons and positrons that are detected by spacecraft in the inner magnetosphere. It is generally believed that these x-ray and gamma-ray emissions are generated, via bremsstrahlung, by energetic runaway electrons that are accelerated by electric fields in the atmosphere. In this paper, we review this newly emerging field of High-Energy Atmospheric Physics, including the production of runaway electrons, the production and propagation of energetic radiation, and the effects of both on atmospheric electrodynamics.

show abstract

Initial leader velocities during intracloud lightning: Possible evidence for a runaway breakdown effect

Cited by 54 publications

References 30 publications

Physical mechanism of initial breakdown pulses and narrow bipolar events in lightning discharges

Physical mechanism of initial breakdown pulses and narrow bipolar events in lightning discharges

Asymmetries in bidirectional leader development of lightning flashes

High-Energy Atmospheric Physics: Terrestrial Gamma-Ray Flashes and Related Phenomena

Contact Info

Product

Resources

About