The Motion of Tropical Storms Under the Influence of a Superimposed Southerly Current

This study deals with the internal and the external influences governing the motion of tropical storms. A theoretical computation is made by assuming a storm to be a vr-vortex within a certain radius of which the air will move as a whole. The storm will describe a circular path if the fluid in which it is embedded does not possess a basic motion. If the fluid possesses a basic motion, say easterlies U, the storm will trace a trochoid, with a net westward progression with a speed U. The amplitude and period of oscillation depend on the wind speed U as well as on the size and intensity of the storm. When the storm comes under the influence of another atmospherical system possessing a south wind, the amplitude of oscillation will be greatly increased by this south wind and the storm will recurve northward. The manner of the recurvature will depend on how the storm enters this south current. Four different 24-hour paths of storms are given after entering the south wind. They are very different from each other; they end in 24 hours at different latitudes and different longitudes. But they have a common feature, i.e., slowing down before recurving and accelerating afterwards.