Estudos sobre Campos Eletricos e Condutividade Associados a Nuvens Eletrificadas na Regiao da America do Sul (Study on Electric Fields and Conductivity Associated with Electrified Clouds in the Region of South America)

摘要

A study of quasi-static electric field and electric conductivity in the Earth's atmosphere, in association with tropospheric electrified clouds is presented. Electric field and conductivity data, obtained by a double-probe balloon-borne detector launched from Cachoeira Paulista, Brazil on April 2, 1980, together with radiosonde balloon, meteorological radar and infrared data, all by a sensor on board the SMS-2 meteorolodial satellite, all measured simultaneously for the first time at the South Hemisphere, are discussed. A theory regarding the calculations of the electric field at the stratosphere due to an electrified cloud is presented. An application of this theory for estimating the distance between a detector and an electrified cloud, using the ratio between the horizontal and the vertical electric fields, is suggested. An analytic theory about atmospheric conductivity measurements by using electric field probes is developed. The analysis of the electric field data showed that they are associated with electrified clouds near the detector, with charges of the order of a few coulombs and without a shielding layer. The analysis of the conductivity measurements showed variations by a factor of two. Such variations, which can be regarded as one of the first evidences that the global atmospheric electric circuit is not static, could play an important role in the study of time variations in this circuit, mainly if it is considered that they occur in a region where the thunderstorm activity is very intense, such as in the South American region.