The first is the influence of latitude factors. Followed by terrain factors and climate factors. Hunan is to the north and Guangdong is to the south. Hunan is a hilly area with many mountains. The force of cold air going south has been weakened a lot. After passing through the Nanling Mountains to reach Guangdong, it is no longer there. Although Hunan and Guangdong both have a subtropical monsoon climate, the deep interior of Hunan is more inclined to a continental climate. Guangdong is close to the sea and is affected by marine factors, so it is somewhat inclined to a humid subtropical climate. Guangdong belongs to the Pearl River Delta plains, and the Pearl River tributaries penetrate deep into the hinterland of Guangdong, making them more susceptible to the warm and humid factors of ocean currents.