The weather in Changsha is so hot. What caused it? Has anyone investigated it?

Changsha, Wuhan, Nanchang and Chongqing are hot cities. Why they are angry is mainly due to geography. These cities are located in the middle of China, and they are not affected by the external climate in summer, so the climate is a bit extreme. It's hot in summer, and there may be ice disaster in winter. Then, the city is hotter than the countryside, mainly because the houses are tall and there are many cars, and it is difficult to disperse the hot air with no amount of concrete. If there are fewer trees in the city, the weather will be hotter.