Onset voltages of atmospheric corona discharges on coniferous trees

In this article, the phenomenon of generation of corona discharges on the t ops of trees and plants is described. In the first part of the text, the co nditions for generation of this electric field which leads to formation of corona discharge and transfer of electric charge between atmosphere and Ear th, are discussed. Experimental results of the onset voltage and its depend ence on the discharge parameters are presented. The coincidence between rel eased species from corona burning point and surrounding atmosphere is also discussed. Equation for the calculation of critical intensity of the electr ic field and onset voltage in dependence on radius of the tip are also disc ussed and compared with experimental data and equations for current-voltage characteristics are described. The attempt to explain differences between theory and measured data is proposed. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.