Physical processes during development of lightning flashes

Mazur, Vladislav

doi:10.1016/s1631-0705(02)01412-3

Cited by 104 publications

(124 citation statements)

References 23 publications

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“…Indeed, when looking at masking in ÀIC flashes which have negative leaders at low altitudes, it is hard to find consistent traces of recoil sources during negative leaders and masking is close to 100% (recoil sources only appearing during breaks in negative leader activity). The examples shown by, e.g., Thomas et al [2000Thomas et al [ , 2001, Mazur [2002], and Rust et al [2005] also support this.…”

Section: Masking Of Positive Leaders and Retrograde (Recoil) Leadersmentioning

confidence: 53%

“…The located sources are mainly coming from negative leaders moving through regions of positively charged cloud particles, but typically weaker sources from positive leader traces inside the negative charge region are often detected as well. These are caused by negative recoil leaders [e.g., Mazur, 2002]. So effectively, the LMA detects negative breakdown at both negative and positive leader sections.…”

Section: Lightning Detection Systemsmentioning

confidence: 99%

“…The lower altitude recoil sources (light blue) between 0.4 and 0.7 s into the flash lie close to the reference slope of 2 · 10 4 m s À1 and can be traced back to the earlier low-altitude sources (green) and the flash origin. The recoil sources clearly continue to be active for almost 200 ms longer than the negative leaders (well known as the junction stage of the flash [Mazur, 2002]). A few very fast events also appear during this stage, mainly within 5 km from the origin, around 6 km altitude like the earlier recoil processes.…”

Section: Examples Of Simple Intracloud Flashes (+Ic)mentioning

confidence: 99%

“…[2] Our current understanding of macroscopic processes going on in lightning flashes is based on the concept of bidirectional leader propagation, proposed by Kasemir [1960] and explored further by Mazur andRuhnke [1993, 1998]. 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).…”

Section: Introductionmentioning

confidence: 99%

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Asymmetries in bidirectional leader development of lightning flashes

2013

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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.

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Section: Masking Of Positive Leaders and Retrograde (Recoil) Leadersmentioning

confidence: 53%

Section: Lightning Detection Systemsmentioning

confidence: 99%

Section: Examples Of Simple Intracloud Flashes (+Ic)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Asymmetries in bidirectional leader development of lightning flashes

2013

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“…The lightning parameterization, on the other hand, maintains a strong feedback between the positive and negative branches to maintain neutrality (before ground contact), and assumes that channels always maintain high conductivity. The assumption of continuously highly conductive and connected channels throughout the discharge is certainly not the case in most lightning, as evidenced, for example, by current cut-off and recoil leaders (e.g., Mazur 2002), where the channel is inferred to have cooled to lower conductivity and is then re-ionized to higher conductivity by the passage of a potential wave. The simulated −CG flashes therefore very likely overestimate the amount of charge brought up to the negative charge region, and thus could reduce the potential bias on the next flash so that it does not reach ground, as may have been the case in the observed storm for the first low IC flash.…”

Section: A Initial and Cg Lightning Activitymentioning

confidence: 99%

Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

Mansell

Ziegler

Bruning

2010

Journal of the Atmospheric Sciences

416

312

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Electrification and lightning are simulated for a small continental multicell storm. The results are consistent with observations and thus provide additional understanding of the charging processes and evolution of this storm. The first six observed lightning flashes, all negative cloud-to-ground (CG) flashes, indicated at least an inverted dipole charge structure (negative charge above positive). Negative CG flashes should be energetically favorable only when the negative charge region contains appreciably more charge than the lower positive region. The simulations support the hypothesis that the negative charge is enhanced by noninductive charge separation higher in the storm that also causes development of an upper positive charge region, resulting in a "bottom-heavy" tripole charge structure. The two-moment microphysics scheme used for this study can predict mass mixing ratio and number concentration of cloud droplets, rain, ice crystals, snow, graupel, and hail. (Hail was not needed for the present study.) Essential details of the scheme are presented. Bulk particle density of graupel and hail can also be predicted, which increases diversity in fall speeds. The prediction of hydrometeor number concentration is critical for effective charge separation at higher temperatures (−5 < T < −15) in the mixed-phase region, where ice crystals are produced by rime fracturing (Hallett-Mossop process) and by splintering of freezing drops.

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Numerical study on relationship between lightning types and distribution of space charge and electric potential

et al. 2014

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The favorable factors that affect the initiation of intracloud (IC) lightning and cloud-to-ground (CG) flashes are investigated by using a fine resolution two-dimensional lightning model. Simulation results indicate that potential at initiation point is a key to decide whether downward leader reaches ground. The absolute values of initiation potential of CG flashes are greater than 30 MV, while the absolute values of initiation potential of IC lightning are basically less than 30 MV. Since potential field is determined by space charge distributions, polarities and types of lightning discharges are also dependent on relative locations and magnitudes of positive and negative charge zones near initiation points. In general, dipoles (positive charge above negative) initiate normal IC lightning and positive CG flashes and inverted dipoles are associated with inverted IC lightning and negative CG flashes. The magnitude of upper charge near initiation point is generally larger than that of lower charge when CG flashes occur, and the two are comparable when IC lightning occur. For CG flashes, the magnitude of lower charge near initiation points should be enough for initiation breakdown, but not so strong that the lower potential well prevents propagation to ground. In addition, CG flashes are initiated within various special charge distributions, only if the reference potentials at initiation point are far away from 0 MV.

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Physical processes during development of lightning flashes

Cited by 104 publications

References 23 publications

Asymmetries in bidirectional leader development of lightning flashes

Asymmetries in bidirectional leader development of lightning flashes

Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

Numerical study on relationship between lightning types and distribution of space charge and electric potential

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