Why is southern Jiangxi cooler than northern Jiangxi?

There are more people in southern Jiangxi than in northern Jiangxi. Gannan is on the edge of "subtropical high". Due to the uplift of mountainous areas in southern Jiangxi, there are strong convective weather and convective rain in the afternoon and evening. Moreover, Gannan is mountainous, with high altitude and high vegetation coverage. It is closer to the ocean than northern and central Jiangxi, and is greatly affected by typhoons, forming a cool summer climate in Gannan. August 10 underground hail such as Xunwu and Ningdu in Ganzhou is the influence of this strong convective weather. Hail generally does not appear in winter, but is the result of strong convective weather in summer and autumn.