In the part where northern and southern air masses collide with each other, a baiu front is formed for several thousands kilometers from east to west and it moves to the north gradually over several months.
北と南の気団が衝突した部分には、東西数千kmに渡って梅雨前線（ばいうぜんせん）ができ、数ヶ月に渡って少しずつ北上していく。