Construção de um instrumento para a medida e estudo do campo elétrico da atmosfera

Abstract

An equipment was constructed for utilizing with the aim at performing the measurement of vertical atmospheric electric field next to the earth surface in Pelotas town, in fair-weather conditions (sky free of clouds) and it uses as a sensor a field mill of the rotating dipole type in stainless steel with 30 centimeter length. This aerial is set in motion by a three-phase motor with 4 poles (approximately 1800 rpm rotation). After the signal is amplified, a synchronous rectifier and a low-pass filter are utilized for separating the signal generated by the vertical atmospheric electric field from the one by the horizontal atmospheric electric field. The resulting signal will be digitized and applied to the inlet access of a computer for performing the data acquiring generated by the equipment. These data will enable to establish the relationship between the vertical atmospheric electric field value and the meteorological parameters in the future, for example, the global temperature. The equipment will be installed in wooden support of 3 meter height. The principal instrument prototypes tested which were proposed to construct, were described and evaluated. A study about the origin and the variation of the vertical atmospheric electric field according to the altitude and daytime, the global electric circuit and the mechanisms of thunderclouds electrization was made. It was also included a review of the instrument types utilized for the maeasurement of the atmospheric electric field since the 20th century starting.