Estudo dos relâmpagos na região sudeste do Brasil em função das características geográficas / A study of geographic influences on the lightning characteristics in the southeastern area of Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

This work presents a study of geographic influences on the lightning characteristics in Minas Gerais, in the Southeastern Brazil, within an area delimited by 18° to 21° S and 43° to 47° W. The period of study was eight years, from October 1988 to November 1996. The lightning and meteorological data were obtained, respectively, by a Lightning Position and Tracking System (LPATS), detection system with an almost constant configuration over the period of study and by National Centers for Environmental Prediction (NCEP). The data showed that several geographic factors affect simultaneously the lightning characteristics. The synoptic conditions, climate, topography and urban centers affect the occurrence and the intensity of lightning, causing more activity in the South part than in the North part of the region studied. The altitude is apparently responsible for the lower flash densities and higher average currents found in the North part as compared to the South part of the region studied. In the Southeast, were to urban center are found (the cities of Belo Horizonte and Contagem), was found an increase in the number of negative flashes and a decrease in the percentage of positive flashes over those urban centers and in the downwind area. The urban heat islands and the urban pollution apparently cause a variation in the thunderstorms? charge distribution affecting the polarity and the density of the flashes. Another factor investigated was the type of soil, but no evidence of its influence on lightning characteristics was found.

ASSUNTO(S)

altitude urban areas industrial areas charge distribution áreas urbanas geologia distribuição de cargas lightning distribuição geográfica metropolitan areas electric discharges descargas elétricas áreas industriais cloud-to-ground discharges altitude descargas nuvem-solo distribuição de corrente geographic distribution current distribution áreas metropolitanas geology relâmpagos

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