@PhDThesis{Paiva:2021:EsLíPo,
               author = "Paiva, Amanda Rom{\~a}o de",
                title = "Estudo dos l{\'{\i}}deres positivos em descargas 
                         atmosf{\'e}ricas",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2021",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2020-08-27",
             keywords = "descargas atmosf{\'e}ricas, l{\'{\i}}der ascendente conectivo, 
                         l{\'{\i}}der ascendente n{\~a}o conectivo, pincel corona, 
                         agulhas, atmosferic discharges, upward connecting leaders, 
                         unconnected upward connecting leaders, corona brush, needle.",
             abstract = "Essa tese apresenta como se comportam os l{\'{\i}}deres 
                         positivos que est{\~a}o presentes em todos os rel{\^a}mpagos. 
                         Com particular relev{\^a}ncia, suas propriedades e 
                         caracter{\'{\i}}sticas determinam o funcionamento dos para-raios 
                         e s{\~a}o a chave para explicar a ramifica{\c{c}}{\~a}o 
                         presente nos rel{\^a}mpagos negativos ascendentes e a intrigante 
                         presen{\c{c}}a de m{\'u}ltiplas descargas nos raios negativos 
                         descendentes. Os para-raios protegem edif{\'{\i}}cios h{\'a} 
                         mais de 260 anos, no entanto at{\'e} recentemente n{\~a}o havia 
                         registros do seu modo de atua{\c{c}}{\~a}o. Os registros 
                         apresentados neste estudo mostram o funcionamento do para-raios em 
                         edif{\'{\i}}cios, e mostram tamb{\'e}m que outros 
                         l{\'{\i}}deres ascendentes n{\~a}o conectivos, isto {\'e}, que 
                         n{\~a}o logram obter conex{\~a}o, podem surgir oriundos de 
                         outros para-raios ou estruturas pr{\'o}ximas. Essas 
                         observa{\c{c}}{\~o}es s{\'o} foram poss{\'{\i}}veis com a 
                         utiliza{\c{c}}{\~a}o de c{\^a}meras de alta velocidade, 
                         principal instrumento utilizado nesse trabalho. Esses 
                         l{\'{\i}}deres, denominados de L{\'{\i}}deres Ascendentes 
                         Conectivos (LACs) e L{\'{\i}}deres Ascendentes 
                         N{\~a}o-Conectivos (LANCs) de polaridade positiva apresentam com 
                         frequ{\^e}ncia a presen{\c{c}}a de pincel corona em suas 
                         extremidades, sendo estas caracterizadas por uma avalanche de 
                         el{\'e}trons que aceleram em dire{\c{c}}{\~a}o {\`a} ponta do 
                         l{\'{\i}}der positivo. Realizando uma an{\'a}lise minuciosa de 
                         diferentes tipos de l{\'{\i}}deres positivos (ascendentes, 
                         descendentes e conectivos) foi poss{\'{\i}}vel estudar o 
                         comportamento do pincel corona. A partir desta an{\'a}lise, 
                         descobriu-se que as ramifica{\c{c}}{\~o}es dos l{\'{\i}}deres 
                         positivos est{\~a}o fortemente ligadas a bifurca{\c{c}}{\~o}es 
                         do pincel corona. Quando a bifurca{\c{c}}{\~a}o do pincel corona 
                         {\'e} malsucedida, observou-se a presen{\c{c}}a de agulhas no 
                         canal dos l{\'{\i}}deres positivos. Essas agulhas nunca haviam 
                         sido observadas por c{\^a}meras de alta velocidade e a sua 
                         exist{\^e}ncia pode ser a resposta para uma das mais fundamentais 
                         perguntas acerca dos raios: porque possuem m{\'u}ltiplas 
                         descargas de retorno. ABSTRACT: This thesis seeks to show how 
                         positive leaders behave, who are present in all lightning strikes. 
                         With particular relevance, its properties and characteristics 
                         determine the functioning of the arresters and are the key to 
                         explain the branching present in the negative upward lightning 
                         strikes and the intriguing presence of multiple discharges in the 
                         negative downward lightning. Lightning rods have protected 
                         buildings for more than 260 years, however, until recently, there 
                         was no record of their operation. The records presented in this 
                         study show the operation of the lightning rod in buildings, and 
                         also show that other unconnected upward connecting leaders (UUL), 
                         that is, who are unable to obtain a connection, may arise from 
                         other lightning rods or nearby structures. These observations were 
                         only possible with the use of highspeed cameras, the main 
                         instrument used in this work. Positive polarity leaders (UCLs and 
                         UUCLs) often have the presence of a corona brush at their ends, 
                         which are characterized by an avalanche of electrons that 
                         accelerate towards the tip of the positive leader. Performing a 
                         thorough analysis of different types of positive leaders (upward, 
                         downward and connecting) it was possible to study the behavior of 
                         the corona brush. From this analysis, it was discovered that the 
                         ramifications of positive leaders are strongly linked to 
                         bifurcations of the corona brush. When the bifurcation of the 
                         corona brush is unsuccessful, the presence of needles in the 
                         channel of positive leaders was observed. These needles had never 
                         been observed by high-speed cameras and their existence may be the 
                         answer to one of the most fundamental questions about lightning: 
                         why they have multiple return discharges.",
            committee = "Wrasse, Cristiano Max (presidente) and Saba, Marcelo 
                         Magalh{\~a}es Fares (orientador) and Schumann, Carina 
                         (orientadora) and Naccarato, Kleber Pinheiro and Alval{\'a}, 
                         Pl{\'{\i}}nio Carlos and Ferro, Marco Ant{\^o}nio da Silva and 
                         Saraiva, Antonio Carlos Varela",
         englishtitle = "Study of positive leaders in atmospheric discharges",
             language = "pt",
                pages = "87",
                  ibi = "8JMKD3MGP3W34R/42U33TB",
                  url = "http://urlib.net/ibi/8JMKD3MGP3W34R/42U33TB",
           targetfile = "publicacao.pdf",
        urlaccessdate = "18 maio 2024"
}