Fouth Report on Vortical Motion; The Function of Steering Line

Abstract

It is explained that along the steering line, there exists a roll of horizontal vortex, which is maintained by the difference of temperature and velocity of air currents at the sliding surface. Near a cyclone there is gradual increase of ascending current as approaching the centre and the end of the said roll is lifted up and winds in the centre, and feeds the vorticity of the centre. The vorticity and cosequantly the kinetic energy of a storm is mainly maintained by this process. This view stands quite in harmony with the theory of Margules, the fact of W. H. Dines and the discovery of J. Bjerknes and H. Solberg.