The Symmetric Instability in Three Layer Model

The symmetric instability is studied by means of three layer model. The results show that there exist the greatest growing rate of the instable disturbance when the optimum coupling of air layer depth (i. e. the vertical scale of the disturbance) with its horizontal scale is obtained. However, the smaller Richardson number Ri is, the greater the ratio of the air layer depth to the horizontal scale of the most instable disturbance is