从海上低空层卷入到台风外围环流的冷空气与台风东南侧暖气流交汇，形成锋面雨，是杭州雨带形成的原因。
The cold air involved into the outer circulation of the typhoon from the low levels met the warm air from the south-east and formed a front associated with the rainbands over Hangzhou .
锋面雨