Role of Electromagnetic Mechanisms in Downburst and Tornado Formation

Abstract

Basing on elecrohydrohynamic (EHD) equations, the article has researched role of thundercloud charge structure, atmospheric electric field (AEF) perturbations under it and giant dielectric permittivity effect (GDPE) in downburst and tornado formation. The authors have first suggested the formula qualitatively describing the process of thundercloud charge structure change from dipole to tripole one and simultaneously accounting the AEF presence even in case of fair weather. Thundercloud vorticity amplification during its recharging process, i.e. its transformation to the tornado-cyclone, is shown to be possible due to electromagnetic forces, not Coriolis ones. Besides that, dipole and tripole cloud charge distributions can create necessary conditions for generating downburst and tornado funnel correspondingly. The paper presents electrohydrodynamic model of forming downburst from a dipole cloud. The work considers total influence of tripole thundercloud charge structure and GDPE on tornado funnel formation and appearing number of accompanying specific phenomena. Using the formula of atmospheric electric field perturbations, the authors have theoretically explained frequently described “hill” ascent on the water surface toward the funnel descending. The authors have also shown that strong AEF perturbations can lead either to funnel descent or to its hanging above the ground.