Autumn rain in western China is a special weather phenomenon of rainy autumn in western China.

(1)① In autumn, there are frequent cold and warm air activities in China. The southwest warm and humid airflow from the Indian Ocean goes northward (2 minutes) along the western edge of the western Pacific subtropical high, and meets the cold air from high latitudes to form frontal rain. (2 points) ② There are many mountainous areas in western China, which is conducive to the uplift of warm and humid air flow and easy to form precipitation. (2 points) (2) Disadvantages: ① The autumn rain in West China is in the mature harvest period of rice and cotton, and continuous rain and insufficient light affect crop maturity and late harvest. (2 points) Benefits: (2) The water resources in western China have increased significantly, providing sufficient water sources for winter wheat sowing. (2 points) Analysis: (1) Reading the map, there are frequent cold and warm air activities in autumn in China. The southwest warm and humid airflow from the Indian Ocean goes northward along the western edge of the western Pacific subtropical high, and meets the cold air from high latitudes to form frontal rain. According to the first material, the autumn rain areas in West China mainly appear in Sichuan, Chongqing, Guizhou, eastern Yunnan, eastern and southern Gansu, Guanzhong and southern Shaanxi, western Hubei and other places, which are mountainous, conducive to the rise of warm and humid air currents and easy to form precipitation. (2) In September, the autumn rain in West China coincided with the mature harvest period of rice and cotton, and continuous rain and insufficient light affected the maturity and late harvest of crops. The favorable factor is that the autumn rain has obviously increased the water resources in West China and provided sufficient water for winter wheat sowing. Test center: regional climate characteristics and causes, and the impact of climate on agriculture.