Triggered lightning strokes originating in clear air

Waldteuffl, P.; Metzger, Philip T.; Boulay, J. L.; Laroche, Pierre; Hubert, P.

doi:10.1029/jc085ic05p02861

Cited by 25 publications

(18 citation statements)

References 6 publications

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“…The actual position of the neutral point is unknown. Similar images were reported by Waldteufel et al (1980) and Saraiva et al (2014). In one case (Stroke 4; see Figure 4), the bidirectional leader and the RS were separated by a no-detectable-luminosity frame.…”

Section: Discussionsupporting

confidence: 79%

Evolution of an Upward Negative Lightning Flash Triggered by a Distant +CG From a 257‐m‐Tall Tower, Including Initiation of Subsequent Strokes

Zhu

Ding

Rakov

et al. 2019

Geophysical Research Letters

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Using the high‐speed optical and electric field records, in conjunction with Earth Networks Total Lightning Network and radar data, we examined in detail the morphology and evolution of an upward negative flash containing six downward leader/upward return stroke sequences terminated on a 257‐m tower in Florida. The upward flash was induced (triggered) by a single‐stroke 50‐kA +CG that occurred about 45 km from the tower. The in‐cloud part of +CG was optically detected to extend toward the tower and appeared to stop at a height of about 3 km above the tower top. The six leader‐return‐stroke sequences were each initiated by a bidirectional leader utilizing the remnants of branches created during the initial stage. Electric field signatures of bidirectional leaders were similar to K‐changes. The upper end of the return‐stroke channel in all six cases exhibited branching and appeared to extend to higher altitudes or/and move closer to Lightning Observatory in Gainesville with increasing stroke order.

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Section: Discussionsupporting

confidence: 79%

Evolution of an Upward Negative Lightning Flash Triggered by a Distant +CG From a 257‐m‐Tall Tower, Including Initiation of Subsequent Strokes

Zhu

Ding

Rakov

et al. 2019

Geophysical Research Letters

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“…[42] The first four strokes of the Debby flash appear to have initiated between 2.8 km and 4.4 km in altitude. Waldteufel et al [1980] analyzed a triggered lightning flash in which 10 strokes were observed, using optical and electric field measurements, to originate in "clear air" at fairly low altitudes. The majority of the 10 strokes originated between 0.5 km and 2 km above ground level.…”

Section: Summary and Discussionmentioning

confidence: 99%

Rocket‐and‐wire triggered lightning in 2012 tropical storm Debby in the absence of natural lightning

et al. 2013

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[1] Lightning Mapping Array source locations, channel base currents, and electric field waveforms are presented for a lightning flash triggered in the rainbands of 2012 tropical storm Debby. The National Lightning Detection Network reported no natural cloud-to-ground discharges within 60 km of the North Florida triggering site for at least 20 h before and 8 h after the triggered flash. Additionally, local electric field mill and wideband antenna networks show no close cloud or cloud-to-ground flashes. The triggering rocket was launched with negative charge overhead producing an electric field at the ground of 5 kV m À1 and in coordination with X-band, dual-polarimetric radar observations of streamers of enhanced precipitation descending from the melting level as they approached the site. The Debby flash consisted of an initial stage (IS) followed by eleven leader/return stroke sequences. The flash exhibited all the processes of normal triggered and natural cloud-to-ground lightning: leader/return stroke sequences, continuing currents, K events, and M components. Additionally, the flash exhibited several exceptional characteristics: three return stroke peak currents greater than 25 kA, one very long, 352 ms, continuing current that transferred about 35 C of charge to ground, and a relatively short, 202 ms, IS containing no initial continuous current pulses. Following a near-vertical upward positive leader attaining 2.8 km height, the IS branched and propagated horizontally at 3.5 km altitude. The flash, exhibiting strokes and continuing current, then ascended to and propagated horizontally at 5.5 km, extending about 25 km south and 15 km east. The 0°C level was near 4.5 km above sea level. It follows from the above that clouds that are not producing natural lightning can represent a triggered lightning hazard to launch vehicles and aircraft.

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“…Of particular interest, a second return stroke followed the first after only 1.3 ms (bottom‐right panel of Figure ; see also, for reports on short interstroke intervals; Rakov & Uman, ; Saba et al, ; Uman & Voshall, ). LMA sources at the time of the second stroke and the ratio of the leader to return stroke field change indicate that the second stroke occurred in clear air below 1 km (see also, for reports of flashes in clear air; Krider, ; Waldteufel et al, ). Additionally, the final current pulse before the return stroke (bottom‐left panel of Figure ) does not have a coincident d E /d t pulse measured (typically due to stepping of the downward leader), suggesting that that current pulse is associated with stepping of the upward connecting leader (see also Biagi et al, , ; Guimaraes et al, ; Hill et al, ; Visacro et al, , ).…”

Section: Methodsmentioning

confidence: 98%

High‐Speed Video and Lightning Mapping Array Observations of In‐Cloud Lightning Leaders and an M Component to Ground

et al. 2019

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High‐speed video (46,000 frames per second) and lightning‐mapping‐array (LMA) data are correlated to determine three‐dimensional properties of in‐cloud lightning leaders (altitudes ranging from 2.78 to 3.81 km) observed in a rocket‐and‐wire triggered lightning flash. Three positive leaders were observed with speeds ranging from 6.1 × 104 to 1.0 × 105 m/s, one of which branched within the camera frame. The upper branch was then traversed twice by attempted negative leaders propagating toward the main channel to ground (speeds of 2.4 × 106 and 1.1 × 107 m/s). Both attempted negative leaders terminated abruptly at the branch point of the remnant channel. In the remnants of a separate positive leader channel, a bidirectional leader initiated, which resulted in an M component whose luminosity and current were measured at ground. Analysis shows that the luminosity wave associated with the entire M component process (propagating 8.8 km from initiation to ground) is highly dispersive, with calculated group velocities ranging from 1 × 107 to 5 × 107 m/s over the dominant signal bandwidth of DC (0 Hz) to 2 kHz.

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Triggered lightning strokes originating in clear air

Cited by 25 publications

References 6 publications

Evolution of an Upward Negative Lightning Flash Triggered by a Distant +CG From a 257‐m‐Tall Tower, Including Initiation of Subsequent Strokes

Evolution of an Upward Negative Lightning Flash Triggered by a Distant +CG From a 257‐m‐Tall Tower, Including Initiation of Subsequent Strokes

Rocket‐and‐wire triggered lightning in 2012 tropical storm Debby in the absence of natural lightning

High‐Speed Video and Lightning Mapping Array Observations of In‐Cloud Lightning Leaders and an M Component to Ground

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