@InProceedings{CamposSabaKrid:2012:MaReLe,
author = "Campos, Leandro Zanella de Souza and Saba, Marcelo Magalh{\~a}es
Fares and Krider, E. Philip",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {ATMO/ECE 489/589 at
The University of Arizona.}",
title = "High-Speed Video and Electric Field Observations of Type Beta-2
Leaders in Negative Lightning: A Manifestation of Recoil Leaders
Initiated Inside the Cloud?",
booktitle = "Proceedings...",
year = "2012",
organization = "International Lightning Detection Conference, 22.",
publisher = "Vaisala",
note = "Informa{\c{c}}{\~o}es Adicionais: Schonland et al. (Progressive
lightning, 6, Proc. Roy. Soc. (London), A168, 455-469, 1938), in
their seminal streak camera studies of lightning, have identified
four events of a peculiar type of negative stepped leader that
they termed \β and 2 , a rather rare variant of the type
\β and leader and in it the second and slower stage of the
leader is associated with the appearance of one or more fast dart
streamers, which travel rapidly down from the cloud along the
previously formed track and cease when they have caught up with
the slower leader-tip . During two different campaigns between
2007 and 2011 in Tucson, Arizona, USA, and in S{\~a}o Jos{\'e}
dos Campos, S{\~a}o Paulo, Brazil, we recorded seven downward
leaders that fit in the type \β and 2 description given by
Schonland et al. (1938). All cases occurred between about 5 and 32
km from a high-speed camera that was operating at 4000 frames per
second and three of them could also have their electric field
changes measured. All the dart streamers that we observed had
speeds between 106 and 107 m s-1, in agreement with previous
observations of recoil leaders (RLs). Also, during the development
of the three cases whose electric field change data was available
it was possible to identify a sequence of microsecond-scale pulses
preceding the development of the Considering the similarities in
the optical and electric field signatures of both phenomena, we
propose that the type \β and 2 negative leaders are the
visible manifestation of the development of RLs that were
initiated inside the cloud and propagate below the cloud-base
during the development of a bipolar, bidirectional leader that
precedes a lightning flash to ground. The RLs are initiated in and
propagate through channels that were previously ionized by the
in-cloud positive portion of a bidirectional leader, eventually
connecting to one of its active branches. When they do an intense
return pulse of luminosity that optically appears as the dart
streamer reported by.",
keywords = "Lightning Physics, Atmospheric Electricity, High-speed video
observations, Recoil leaders, Lightning Leaders.",
abstract = "Schonland et al. (Progressive lightning, 6, Proc. Roy. Soc.
(London), A168, 455-469, 1938), in their seminal streak camera
studies of lightning, have identified four events of a peculiar
type of negative stepped leader that they termed \β2, a
rather rare variant of the type \β leader and in it the
second and slower stage of the leader is associated with the
appearance of one or more fast dart streamers, which travel
rapidly down from the cloud along the previously formed track and
cease when they have caught up with the slower leader-tip. During
two different campaigns between 2007 and 2011 in Tucson, Arizona,
USA, and in S{\~a}o Jos{\'e} dos Campos, S{\~a}o Paulo, Brazil,
we recorded seven downward leaders that fit in the type \β2
description given by Schonland et al. (1938). All cases occurred
between about 5 and 32 km from a high-speed camera that was
operating at 4000 frames per second and three of them could also
have their electric field changes measured. All the dart streamers
that we observed had speeds between 106 and 107 m s-1, in
agreement with previous observations of recoil leaders (RLs).
Also, during the development of the three cases whose electric
field change data was available it was possible to identify a
sequence of microsecond-scale pulses preceding the development of
the Considering the similarities in the optical and electric field
signatures of both phenomena, we propose that the type \β2
negative leaders are the visible manifestation of the development
of RLs that were initiated inside the cloud and propagate below
the cloud-base during the development of a bipolar, bidirectional
leader that precedes a lightning flash to ground. The RLs are
initiated in and propagate through channels that were previously
ionized by the in-cloud positive portion of a bidirectional
leader, eventually connecting to one of its active branches. When
they do an intense return pulse of luminosity that optically
appears as the dart streamer reported by Schonland et al. (1938)
is produced and propagates until it reaches the lower tip of the
negative downward portion. After the RL process is completed the
downward negative stepped leader portion of the bidirectional
leader continues its development normally, with the possibility of
occurrence of other RLs, until it reaches the ground and produces
a return stroke.",
conference-location = "Broomfield Tucson",
conference-year = "2-3 Apr. 2012",
label = "lattes: 4161737266837399 1 CamposSabaKrid:2012:MaReLe",
language = "en",
targetfile = "High-Speed Video and Electric Field Observations of Type Beta-2
Leaders in.pdf",
volume = "1",
urlaccessdate = "28 abr. 2024"
}