@InProceedings{SaraivaCWZAPHBBMB:2014:OpEvIn,
author = "Saraiva, Ant{\^o}nio Carlos V. and Campos, Leandro Zanella de
Souza and Williams, Earle R. and Zepka, Gisele dos Santos and
Alves, J{\'e}ferson and Pinto Jr., Osmar and Heckman, Stan and
Buzato, Tiago Santos and Bailey, Jeffrey C. and Morales, Carlos A.
and Blakeslee, Richard J.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Massachusetts
Institute of Technology} and {Instituto Nacional de Pesquisas
Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais
(INPE)} and {Instituto Nacional de Pesquisas Espaciais (INPE)} and
Earth Networks Germantown, MD, USA and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {University of Alabama in
Huntsville} and {Universidade de S{\~a}o Paulo (USP)} and {NASA
Marshall Space Flight Center}",
title = "Optical evidences of the inception mechanisms of natural bipolar
cloud-to-ground lightning",
booktitle = "Proceedings...",
year = "2014",
organization = "International Lightning Detection Conference, 23. (ILDC); and
International Lightning Meteorology Conference, 5 (ILMC).",
publisher = "Vaisala",
note = "Informa{\c{c}}{\~o}es Adicionais: High-speed video records of
two bipolar cloud-to-ground flashes were analyzed in detail. They
were both initiated by single positive return strokes and were
followed by more than one subsequent negative stroke. Due to the
elevated cloud-base height of its parent thunderstorm, the
initiation processes of each subsequent stroke could be registered
optically below cloud base. In the first event (Case 1) it was
possible to observe that all four subsequent negative strokes were
initiated by recoil leaders that retraced one horizontal channel
segment previously ionized by the positive leader that preceded
the first stroke. Those recoil leaders connected to the original
vertical channel segment and propagated towards ground, producing
four subsequent strokes that had the same ground contact point of
the original positive discharge. The second event (Case 2), on the
other hand, presented fifteen subsequent strokes that were
initiated by recoil leaders that did not reach the original
channel of the positive stroke. They diverged vertically towards
ground, making contact approximately 11 kilometers away from the
original positive strike point. These are the first optical
evidences that both single- and multiple-channel bipolar flashes
occur as a consequence of recoil leader activity in the branches
of the initial positive return stroke. For both events their total
channel length increased progressively with time at a growth rate
equivalent to a propagation speed of the order of 104 m/s,
comparable to those reported for typical positive leaders..",
keywords = "bipolar lightning, atmospheric electricity, recoil leaders,
bidirectional leader model, dart leaders, positive lightning.",
abstract = "High-speed video records of two bipolar cloud-to-ground flashes
were analyzed in detail. They were both initiated by single
positive return strokes and were followed by more than one
subsequent negative stroke. Due to the elevated cloud-base height
of its parent thunderstorm, the initiation processes of each
subsequent stroke could be registered optically below cloud base.
In the first event (Case 1) it was possible to observe that all
four subsequent negative strokes were initiated by recoil leaders
that retraced one horizontal channel segment previously ionized by
the positive leader that preceded the first stroke. Those recoil
leaders connected to the original vertical channel segment and
propagated towards ground, producing four subsequent strokes that
had the same ground contact point of the original positive
discharge. The second event (Case 2), on the other hand, presented
fifteen subsequent strokes that were initiated by recoil leaders
that did not reach the original channel of the positive stroke.
They diverged vertically towards ground, making contact
approximately 11 kilometers away from the original positive strike
point. These are the first optical evidences that both single- and
multiple-channel bipolar flashes occur as a consequence of recoil
leader activity in the branches of the initial positive return
stroke. For both events their total channel length increased
progressively with time at a growth rate equivalent to a
propagation speed of the order of 104 m/s, comparable to those
reported for typical positive leaders.",
conference-location = "Tucson",
conference-year = "mar. 18-19, 2014 / mar. 20-21, 2014",
label = "lattes: 4161737266837399 2 SaraivaCWZAPHBBMB:2014:OpEvIn",
language = "en",
targetfile = "Saraiva et al-Optical evidences of the inception mechanisms of
natural bipolar CGL-2014-ILDC-ILMC.pdf",
volume = "1",
urlaccessdate = "24 abr. 2024"
}