Determining the morphology of tornado-like vortices depending on thermal gradients: A numerical study

Abstract

In this work, we study the role of the horizontal temperature differences on the top and bottom, their combined effect, and their relation to the vertical temperature difference in the development of traditional or reversed funnel-shaped vortices in a rotating cylinder inhomogeneously cooled on the top and heated at the bottom. These thermal inhomogeneities on upper and lower levels are observed in the formation of atmospheric vortices. Our numerical results show that if the thermal inhomogeneity is stronger on the top, an axisymmetric traditional funnel-shaped tornado-like vortex with an inner updraft of warmer air is developed. On the contrary, if the thermal inhomogeneity is stronger at lower levels, an axisymmetric reversed funnel-shaped vortex develops with an inner downdraft of cooler air. When thermal inhomogeneities are equal at both levels, it is the grade of localization of the heating (at the bottom) or the cooling (at the top), which determines the formation of a V-vortex or an inverted V-vortex, respectively. We perform a force balance analysis to give a physical insight into the phenomena. The results evidence the relevance of the thermal conditions on the vortical structures developed, and they may contribute to the understanding of the morphology of atmospheric vortices, such as tornadoes or cold air funnels.