@PhDThesis{Ballarotti:2015:ReLíPo,
author = "Ballarotti, Maur{\'{\i}}cio Grade",
title = "Redesenvolvimento do l{\'{\i}}der positivo no rel{\^a}mpago",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2015",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2015-04-23",
keywords = "rel{\^a}mpago, l{\'{\i}}der, descarga el{\'e}trica, descarga
atmosf{\'e}rica, quebra de rigidez, lightning, leader, electrical
discharge, atmospheric discharge, electrical breakdown.",
abstract = "Neste trabalho {\'e} caracterizado o processo interno do
rel{\^a}mpago chamado ent{\~a}o de \${{"}}\$l{\'{\i}}der de
recuo\${{"}}\$(LR), respons{\'a}vel pelo redesenvolvimento do
l{\'{\i}}der positivo atrav{\'e}s da quebra de rigidez nos
diversos tipos de rel{\^a}mpagos. {\'E} o processo que, de certo
modo, foi menos estudado e compreendido, ao mesmo tempo em que tem
sido observado indiretamente h{\'a} quase um s{\'e}culo. A
revis{\~a}o da literatura contemplou os seguintes t{\'o}picos: o
ambiente el{\'e}trico do rel{\^a}mpago na nuvem de tempestade;
os processos internos do rel{\^a}mpago nuvem-solo negativo
(quebra de rigidez preliminar, l{\'{\i}}der escalonado,
l{\'{\i}}der ascendente conectivo, descarga de retorno,
l{\'{\i}}deres subsequentes, corrente cont{\'{\i}}nua e
componente M, e processos K e J), do nuvem-solo positivo e dos
ascendentes; o l{\'{\i}}der de recuo; e o rel{\^a}mpago como um
l{\'{\i}}der bidirecional. Foram realizadas duas an{\'a}lises
paralelas de registros do l{\'{\i}}der positivo, com foco no seu
redesenvolvimento: uma baseada em c{\^a}mera r{\'a}pida com o
l{\'{\i}}der exposto fora da nuvem para 18 rel{\^a}mpagos
nuvem-solo positivos e ascendentes negativos, e outra baseada em
c{\^a}mera r{\'a}pida e antenas de campo el{\'e}trico com o
l{\'{\i}}der dentro da nuvem para 16 rel{\^a}mpagos nuvem-solo
negativos. As duas an{\'a}lises foram discutidas em comum nos
seguintes aspectos: caracter{\'{\i}}sticas do l{\'{\i}}der de
recuo (regime, sentido de propaga{\c{c}}{\~a}o, local de
inicia{\c{c}}{\~a}o e assinatura de campo el{\'e}trico); o
l{\'{\i}}der de recuo na estrutura do l{\'{\i}}der positivo
(propaga{\c{c}}{\~a}o do ramo que sofre a ocorr{\^e}ncia dos
l{\'{\i}}deres de recuo, localiza{\c{c}}{\~a}o de uma
s{\'e}rie de l{\'{\i}}deres de recuo, dire{\c{c}}{\~a}o de
propaga{\c{c}}{\~a}o do l{\'{\i}}der de recuo,
fun{\c{c}}{\~o}es do l{\'{\i}}der de recuo e extens{\~a}o de
sua propaga{\c{c}}{\~a}o, taxas de gera{\c{c}}{\~a}o e
particularidades nos diferentes tipos de rel{\^a}mpagos);
intera{\c{c}}{\~a}o do l{\'{\i}}der de recuo com outros
processos (agrupamento, interatividade, interatividade
c{\'{\i}}clica e taxas m{\'e}dias de gera{\c{c}}{\~a}o de
l{\'{\i}}deres de recuo durante diferentes processos no
nuvem-solo negativo); e sobre o mecanismo de disparo do LR. Um
resultado particularmente importante desta tese trata sobre o
papel de uma m{\'{\i}}nima diferen{\c{c}}a de potencial sobre o
ramo deca{\'{\i}}do para o disparo do l{\'{\i}}der de recuo.
Baseado em diversas evid{\^e}ncias sintetizadas ao longo das duas
an{\'a}lises, foi elaborado um modelo el{\'e}trico simplificado
do disparo do l{\'{\i}}der de recuo, aplic{\'a}vel a diferentes
tipos e situa{\c{c}}{\~o}es observadas de rel{\^a}mpagos. Tal
diferen{\c{c}}a de potencial {\'e} apresentada em
fun{\c{c}}{\~a}o da temperatura e do comprimento do ramo
deca{\'{\i}}do. Sugere-se a mudan{\c{c}}a na nomenclatura de
l{\'{\i}}der de recuo para l{\'{\i}}der de redesenvolvimento.
ABSTRACT: This thesis characterizes the internal lightning process
called recoil leader, which is responsible for the positive leader
redevelopment based on breakdown in many types of lightning
discharges. This process is somehow the least analyzed and
understood, at the same time that it has been indirectly observed
for almost a century. The literature review treated the following
subjects: thunderstorm electrical environment for lightning;
internal processes of the negative cloud-to-ground lightning
(preliminary breakdown, stepped-leader, upward connecting leader,
return stroke, subsequent leaders, continuing current and M
component, K and J processes), of the positive cloud-to-ground and
the upward lightning; recoil leader; and lightning as a
bidirectional leader. Two analyses of the positive leader were
performed in parallel, focusing on its redevelopment: one based on
high-speed camera records of exposed leader (outside the cloud) on
18 events of positive cloud-to-ground and negative upwards, and
the other based on high-speed camera and electric field antennas
records of hidden leader (inside the cloud) on 16 events of
negative cloud-to-ground lightning. Both analyses were discussed
together in the following topics: recoil leader characteristics
(regime, propagation direction, initiation location and electric
field signature); recoil leader in the positive leader structure
(branch propagation during recoil leader, location of a recoil
leader series, propagation direction and extent of the recoil
leader, recoil leader roles, generation rates, particular
behaviors in different lightning types); recoil leader interaction
with other process (grouping, interactivity, cyclic interactivity,
recoil leader generating rates during different processes of the
negative cloud-to-ground lightning); and about the recoil leader
triggering mechanism. A particularly important result of the
present thesis shows the key role of a minimum potential
difference over the decayed branch as an important condition for
recoil leader triggering. Based on several evidences synthesized
from both analyses, a simplified electrical model of the recoil
leader triggering was developed, and applied to different
lightning types and conditions. Such potential difference is
presented as a function of decayed branch temperature and length.
In terms of nomenclature, it is also suggested redevelopment
leader instead of recoil leader.",
committee = "Lago, Alisson Dal (presidente) and Pinto Junior, Osmar
(orientador) and Saba, Marcelo Magalh{\~a}es Fares (orientador)
and Souza, Jonas Rodrigues de and Piantini, Alexandre and
Martinez, Manuel Luiz Barreira and Ferro, Marco Antonio da Silva",
copyholder = "SID/SCD",
englishtitle = "Positive leader redevelopment in lightning",
language = "pt",
pages = "226",
ibi = "8JMKD3MGP3W34P/3J7Q4E8",
url = "http://urlib.net/ibi/8JMKD3MGP3W34P/3J7Q4E8",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}