Theory on the Funnel Structure of Tornado

Abstract Tornado is a small‐scale system whose horizontal and vertical velocities are maximum in the atmosphere. From the governing equations satisfying the balance among pressure gradient force, inertial centrifugal force and viscous force, the three‐dimensional velocities of tornado are obtained, and then its funnel structure is shown theoretically. Here it is shown that the funnel structure consists of vortex flow and jet flow, where vortex flow is resulted from inertial centrifugal force and jet flow from strong convection by the horizontal convergence. At the same time, it is shown that the tornado is formed under the very unstable atmospheric stratification conditions.