How is the haze weather formed?

Natural climate is the main reason that affects the number of days of urban haze.

Large-scale haze weather mainly appears in the situation of large-scale atmospheric circulation with weak cold air and good water vapor conditions in autumn and winter, and the low altitude near the ground is still wind or breeze. Therefore, mountainous areas and valley areas (some cities in Shanxi, Changsha in Hunan, etc. ) and plain rivers and lakes (such as Nanjing, Hefei, Hangzhou, etc. It is easier to form haze weather, while dry and windy areas are not easy to form.