High‐Speed Video Observations of Natural Lightning Attachment Process With Framing Rates up to Half a Million Frames per Second

Qi, Qi; Lyu, Weitao; Ma, Ying; Wu, Bin; Chen, Lyuwen; Jiang, Ruijiao; Zhu, Yanan; Rakov, Vladimir A.

doi:10.1029/2019gl085072

Cited by 13 publications

(15 citation statements)

References 35 publications

(62 reference statements)

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“…Qi et al (2016) recorded 23 space leaders in a natural lightning stepped-leader occurring 1-8 m ahead of the downward leader tip with lengths of 1-13 m. Jiang et al (2017) observed 31 space leaders occurring, on average, 3.6 m ahead of the leader tip. Srivastava et al (2019) and Qi et al (2019) reported average space-leader lengths of 2.1 and 3 m, respectively. Note that all lengths and distances in the studies discussed above are two-dimensional (2-D).…”

Section: Insights On Space-leader Characteristics and Evolutionmentioning

confidence: 99%

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Insights on Space‐Leader Characteristics and Evolution in Natural Negative Cloud‐to‐Ground Lightning

Khounate

Nag

Plaisir

et al. 2021

Geophysical Research Letters

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A space stem is a luminous plasma segment that has been observed to form ahead of the leader tip during the negative leader stepping process (Biagi et al., 2009(Biagi et al., , 2010Gorin et al., 1976). A space stem may eventually thermalize, undergo a sharp increase in conductivity, and develop into a space leader. Due to the intensification of electric field at its extremities, a space leader can start extending toward the pre-existing leader channel (PELC), eventually connecting with the PELC, leading to its extension and the completion of a new leader step. Characterizing the details of the formation and progression of space leaders is, therefore, essential for understanding the leader stepping process as well as the extent to which electrical characteristics of the PELC influence the formation and extension of space leaders. Gorin et al. (1976) first observed in laboratory spark experiments, space stems which were incepted in the vicinity of the negative leader tip and later evolved into space leaders that merged with the negative primary leader channel, leading to its extension. Biagi et al. (2009Biagi et al. ( , 2010 were the first to report separated luminous segments that they believed were space stems and space leaders in dart-stepped leaders of triggered lightning flashes using high-speed video cameras; they observed 1-4 m long luminous segments 1-10 m ahead of the leaders. Biagi et al. (2014) observed eight luminous segments 1-6 m in length and 3-8 m ahead of the downward stepped leader preceding the first stroke of an altitude-triggered flash. Hill et al. (2011) and

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Section: Insights On Space-leader Characteristics and Evolutionmentioning

confidence: 99%

“…(2019) and Qi et al. (2019) reported average space‐leader lengths of 2.1 and 3 m, respectively. Note that all lengths and distances in the studies discussed above are two‐dimensional (2‐D).…”

Section: Introductionmentioning

confidence: 97%

Insights on Space‐Leader Characteristics and Evolution in Natural Negative Cloud‐to‐Ground Lightning

Khounate

Nag

Plaisir

et al. 2021

Geophysical Research Letters

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“…Qi et al. (2019) estimated the SDs of four lightning flashes terminated on a building with 100 m height. Note that, the above studies on the SD were obtained from the optical observations of lightning flashes striking a particular object with a certain height.…”

Section: Introductionmentioning

confidence: 99%

“…Visacro et al (2017) discussed different approaches to estimate the SD and reported SDs of 17 cloud-to-ground lightning flashes striking a 60 m high grounded structure. Qi et al (2019) estimated the SDs of four lightning flashes terminated on a building with 100 m height. Note that, the above studies on the SD were obtained from the optical observations of lightning flashes striking a particular object with a certain height.…”

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confidence: 99%

Two‐Dimensional Striking Distance of Lightning Flashes to a Cluster of Tall Buildings in Guangzhou

Lyu

Wang

et al. 2021

JGR Atmospheres

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Based on the high‐speed video records of 54 lightning flashes striking on a cluster of tall buildings in Guangzhou and the return stroke peak currents provided by lightning location systems, this paper analyzed the two‐dimensional (2D) first‐return‐stroke striking distances (SD) of lightning flashes to buildings with a height ranging from 100 to 600 m. Three methods, including one proposed in this study, have been used to estimate the 2D SD. The results with different methods basically agree with each other and show that the height and the top geometry of the structure on which lightning terminates are key factors that affect the SD. The correlation between the SD and the peak return stroke current appeared very scattered, particularly in the cases when each building was considered separately. Besides, we found that: (a) the estimated 2D average initiation speed of upward connecting leader (UCL) on different buildings are similar, ranging from 4.9 to 23 × 104 m/s, with an average of 13.4 × 104 m/s; (b) about 87% (27/31) flashes that struck on buildings with simple top shape only have one upward leader observed, while for buildings with complicated top shape, only 26% (6/23) flash cases have one upward leader observed; (c) for the 36 flashes to four tall buildings with heights higher than 300 m, the 2D average speed ratio of the downward leader and the UCL is 0.74 during the last 0.1 ms before the first return stroke.

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“…However, most of the studies on the characterization of CG flashes are performed using electric and magnetic field measurement systems, perhaps because of the high cost of high‐speed cameras. Another reason could be the smaller coverage area of high‐speed cameras (from 350 m to about 17 km, e.g., (Qi et al., 2018, 2019; Tran & Rakov, 2015, 2017; Wang et al., 2020)) in comparison with field measurements (from few meters to hundreds of kilometers, e.g., (Haddad et al., 2012; Leal & Rakov, 2021a, 2021b; Y. Zhu, Rakov et al., 2015)).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Negative Cloud‐To‐Ground Flashes Observed in the Brazilian Amazon Region

et al. 2021

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Among the different types of lighting that occur on Earth, the cloud-to-ground (CG) lightning is the one most studied and investigated phenomenon because of its real threat to human beings, electric power systems, telecommunication systems, and electrical and electronic systems in general. The downward CG flashes consist of a single return-stroke (RS) or a first RS, followed by several subsequent strokes (SS). The CG lightning flash usually involves a preliminary breakdown (PB) process followed by a downward leader and a RS that connects to the ground during the attachment process. In negative RS, negative charge is effectively transported to the ground, and in positive RS, the opposite charge transfer occurs (Uman, 1987). The incidence of CG flashes is estimated to be 25% of all lightning occurrences on Earth (Rakov, 2016;Rakov & Uman, 2003). In the U.S, according to Medici et al. (2017), the incidence of CG flashes varies from 15% to 44%. The characteristics of CG lightning are in the field of interest for engineering applications, geophysical research, meteorology, among other fields of study.It is known that lightning parameters can vary from one storm to another (Saraiva et al., 2010;Y. Zhu, Rakov et al., 2015). Also, lightning parameters can change from one region to another region of the globe due to the regional physiography and atmospheric conditions (Kilinc & Beringer, 2007;Kuleshov, 2004;Mushtaq et al., 2018) and, mainly regarding different latitudes (Pinto et al., 1997;Thomson, 1980b). However, Thomson (1980b) suggested that those differences could be because of the different methodologies employed to measure the parameters, for instance, different sample rates of digitizers, different trigger thresholds, and different equipment in general. Recently, Cooray et al. (2020), developed a theory to explain why the peak current in negative return strokes increases as the latitude decreases. They showed that this dependence is related to the difference in the heights of the charge centers in the thunderclouds at different geographical regions. The Amazon region is located in the low latitude region, and so, high-intensity lightning flashes are expected. Those high-intensity CG flashes were observed by Almeida et al. (2012) in the eastern Amazon region.

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High‐Speed Video Observations of Natural Lightning Attachment Process With Framing Rates up to Half a Million Frames per Second

Cited by 13 publications

References 35 publications

Insights on Space‐Leader Characteristics and Evolution in Natural Negative Cloud‐to‐Ground Lightning

Insights on Space‐Leader Characteristics and Evolution in Natural Negative Cloud‐to‐Ground Lightning

Two‐Dimensional Striking Distance of Lightning Flashes to a Cluster of Tall Buildings in Guangzhou

Characteristics of Negative Cloud‐To‐Ground Flashes Observed in the Brazilian Amazon Region

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