Judgment Criteria for the Four Great Stoves

The New Four Hot Stoves announced in 2010, an analysis and study of "hot cities", consider factors including heat index (an index that mainly considers the comprehensive impact of temperature and relative humidity on human comfort), Number of high temperature days, number of consecutive high temperature days, average maximum and minimum temperatures in summer, etc. Scientifically, the number of days with high temperatures above 35°C, as well as the extreme high temperature value and relative humidity are used to measure the heat of a city. There are more than 20 days with the highest temperature exceeding 35°C in a year, and there have been days above 40°C. In hot weather, people call such cities "furnaces".

Different from indicators such as the number of extreme maximum temperatures or high-temperature weather (daily maximum temperature 35°C), the heat index comprehensively considers the impact of temperature and relative humidity on human comfort, and has a unique calculation formula. Usually It is believed that the greater the heat index value, the more uncomfortable the human body will feel. Because under high temperature conditions, if the air is dry, heat can be dissipated through sweating and the evaporation of sweat, but if the air humidity is too high, the efficiency of the person's cooling system will decrease, and the sweat cannot evaporate away, making you feel very uncomfortable. .

Nanjing, Chongqing, Wuhan, Nanchang and other cities do rank at the top of the list for hot days every year. According to statistics, the four major cities have an average of 19.3 days per year of high temperatures above 35°C in summer, and an average of 4.5 days per year of high temperatures above 37°C; an average of 13.2 days per year of minimum temperatures above 28°C at night, and an average of 13.2 days per year of minimum temperatures above 30°C every year. 1.9 days. Coupled with the sweltering heat of "no wind in the city", it is no wonder that it has the name of "stove".

After the China Meteorological Administration announced the "New Four Furnaces" in July 2013, some people in the industry questioned that it was inappropriate to only use the number of high-temperature days to represent the "furnace" cities. Temperature, humidity, wind speed, high temperature duration, Factors such as nighttime temperature must be taken into consideration, especially the "sensory temperature" that ordinary people can best understand. Rather than a "stove", it might as well be replaced by a "heat index". According to the results of the 2010 study, although the traditional "hot pot" cities such as Wuhan and Nanjing that the public used to know are still on the list, they have dropped out of the "top four" rankings.

The low ranking of Wuhan and Nanjing has a lot to do with the temporal changes in China's climate. Meteorological research shows that climate change in northern and southern China has an oscillation cycle of about 20 to 30 years. In the 1990s, the Yangtze River Basin had more precipitation and severe floods, so the temperature was relatively low and there were fewer high-temperature days. Looking at the entire 30-year time scale, due to the influence of the 1990s, the temperature growth rate of cities in the Yangtze River Basin is not as fast as other cities, especially slower than many cities in northern China. The official Weibo account of China Meteorological Channel @China Meteorology released a new ranking of the "Four Hot Stoves" in the Mainland in mid-July. Fuzhou became the king of high temperatures and won the title of "Champion", with Chongqing and Hangzhou ranking second and third. Nanjing fell out of the top ten, ranking 14th.

The new ranking of "stove cities" in the Mainland: 1 Fuzhou 2 Chongqing 3 Hangzhou 4 Haikou 5 Changsha 6 Nanchang 7 Wuhan 8 Nanning 9 Xi'an 10 Guangzhou 11 Shijiazhuang 12 Zhengzhou 13 Hefei 14 Nanjing 15 Jinan 16 Shanghai