Why is the weather in Kunming so good?

Why is it not cold in winter only in Yunnan? Let's look at an example first. Kunming, the capital of ancient Yunnan Province, was known as "an unbeaten city in spring, warm in winter and cool in summer". Kunming and Guilin in Guangxi are at the same latitude. The average temperature in January in the two places is basically the same, both around 7.8℃, but the altitude of Kunming is1892m, which is higher than that of Guilin1720m! If the vertical gradient of winter average temperature in Yunnan drops by 0.45℃ for every rise 100 m, and Guilin is corrected to the same altitude as Kunming, the average temperature in Kunming 1 month will be only 0℃. Conversely, if the temperature in Kunming is corrected to the height of Guilin, Kunming is also 7.8℃ higher than Guilin, that is, 15.6℃. Why is Yunnan particularly warm in winter? Yunnan is warm in winter for a reason, such as the land and the sky. First of all, there are tall mountains in eastern Yunnan, such as Wumeng Mountain, which block the cold air from Siberia from north to south and then to west. But even this would not be enough In winter, the dry and warm westerly airflow from southwest Asia prevails over Yunnan. The higher the airflow, the stronger it is (westerly jet at high altitude). So the mountain was blocked, the westerly airflow was blocked, and the heavens and the earth joined forces to finally block the cold air in the east of Yunnan Plateau. Yunnan is often bathed in warm westerly airflow in winter, which is naturally warm as spring. The eastern part of China, such as Guilin, is naturally colder because it is often "soaked" by the cold air sea going south frequently. This is why the eastern part of China at the same latitude has a subtropical climate, while the Yunnan Valley has a tropical climate. When winter came to Yunnan, the north wind in the eastern region roared south, and the temperature plummeted in a large area. Yunnan was still sunny, just like living in another world and having a paradise. Yunnan is not only rich in animal and plant resources, but also a province with strong local climate characteristics in China. Xishuangbanna in southern Yunnan is very warm in winter, and the temperature difference between winter and summer is greatly reduced, but the rainy season and dry season are very clear. So, like Indochina Peninsula in the south, the whole year is divided into dry season (11-March), hot season (April-May) and rainy season (June-September), that is, three seasons a year. Plants are flourishing in most parts of Yunnan, but the mountains in the north of Hengduan Mountain are the highest, and the foehn effect caused by mountainous areas has caused local valleys of Jinsha River to dry up. For example, the annual rainfall of Benzilan in Deqin County is only 336 mm (the annual rainfall of Gongshan, which is only 85 kilometers southwest, is 1667 mm).