Why is Liupanshui also called Du Liang?

Liupanshui, the cool capital of China, was awarded the title of "Cool Capital of China" by relevant meteorologists and evaluation by domestic authorities, and became the first city brand built by using climate resources in China. Experts from China Academy of Sciences, State Environmental Protection Administration and China Meteorological Bureau made a scientific analysis of the summer climate characteristics of Liupanshui City through observation and detection experiments, and concluded that it is "cool and comfortable, moist and fresh, with moderate ultraviolet radiation" and has its own characteristics, so it can be called "the cool capital of China". Zhu Degui, director of the Liupanshui Meteorological Bureau, said that Liupanshui is located at the intersection of the water vapor circulation in the Bay of Bengal, the cold air circulation in Siberia and the subtropical high circulation in the Pacific Ocean, with abundant rain and suitable temperature. Although it is located in the plateau above 1 1,800 meters above sea level, the ultraviolet radiation is weakened by the atmospheric clouds with a thickness of 1 1,000 meters and a humidity of 70%, which makes the ultraviolet radiation milder. The unique geographical location makes Liupanshui's climate cool, with no summer all year round and spring and autumn connected. By searching the observation data of more than 730 weather stations in China and comparing them with the national 17 summer resorts, experts found that Liupanshui is obviously superior in human comfort. The average temperature in summer is less than 20℃, and the average temperatures in June, July and August are 18.3℃, 19.8℃ and 19.2 respectively. I feel comfortable 96% of the time in summer, 9 1 day during the day and 89 days at night. The city belongs to subtropical humid monsoon climate zone. The overall temperature has not changed much, with annual average temperature 13- 14℃, monthly average temperature 13-6.3℃ and July average temperature 19.8-22.0℃. The frost-free period is 230-300 days. The rainfall is1200-1500mm. Warm in winter and cool in summer, the climate is pleasant. The terrain fluctuates greatly, and the climate difference in some areas is obvious. The total water volume of the city is about1421800 million cubic meters, of which the average annual flow of surface water is 6.4 billion cubic meters.