台风移动的一个简单模型

A SIMPLE PATTERN OF TYPHOON TRACKS

本文分析了在江河中摆渡船的运行，并将台风比拟为摆渡船，给出了台风移动的一个简单模型。研究指出：若船速为，流速为，船驶向对岸的目标为Ｆ，则当时，船的运行轨迹为一直线；而当时，船的运行轨迹为以Ｆ为焦点的抛物线，将上述分析应用于台风，则台风速度相当于，台风环境空气的速度（即引导气流）相当于，因台风主要是切向运动，可利用角动量守恒原理计算它在台风范围内的平均值来表示，而按通常的引导气流计算方法求得。

In this paper the movement of ferry-boat is analyzed. Comparing the typhoon with the ferry-boat a simple pattern of typhoon tracks is presented. The research shows that let VI and VZbe the ship and current velocities, respectively, the ship takes aim at F, such that whenl 6, I W I V, l, the track of ferry-boat is a straight line; when 1 V, I ￣ I V, I its track is aparabola with the focus F. Applying the above analysis to the typhoon tracks and comparing thetyphoon with the ferry--boat and are corresponding to the velocities of typhoon and steering flow,respectively. Because the prime motion in typhoon is tangential,1 is regarded asthe mean value of the tangential velocity 'which is calculated by means of the conservation of angular momentum, while,I is obtained by the steering flow.