Why is the air pollution getting more and more serious in autumn and winter, and the clear sky in Wan Li can only last for one or two days?

I haven't lived in other provinces and cities for a long time and have no say in their air quality. But I have lived in Chengdu, Sichuan for a long time, and I still have a say in the air quality here.

I remember when I returned to Chengdu in 2009, all localities were vigorously engaged in construction. Either build roads and bridges or develop real estate, and the number of cars is unlimited. At that time, the air quality was not very good, especially in autumn and winter, and it was gray every day, so it was rare to see a thorough sky. Even if it is sunny, I think the sun is "hairy", not the kind of clear sky and red sun that we often see in summer.

Generally speaking, the air quality in Chengdu has improved a lot in recent years. Especially in recent years, environmental protection rectification and car tail number restriction have played a great role in improving Chengdu's air quality. The sky in Chengdu is getting bluer and bluer, and the number of seeing snow-capped mountains is increasing every year.

Then why is the air pollution in Chengdu serious in autumn and winter? Personally, I think there are several reasons.

First, geographical factors.

As we all know, Sichuan is a basin surrounded by mountains, forming a circular barrier. Chengdu is located in the hinterland of the basin, which leads to the timely diffusion of pollutants.

The second is the factor of less precipitation in autumn and winter.

It's rainy and windy in summer, so pollutants can't gather. There is little rain and wind in autumn and winter, which leads to easy accumulation of pollutants. If there is no effective way to remove pollutants, the air quality will get worse and worse.

Third, atmospheric factors.

Static heavy pollution weather refers to the large-scale accumulation of pollutants due to meteorological conditions that are not conducive to the diffusion of atmospheric pollutants. According to the Chengdu Meteorological Observatory, Chengdu is very quiet these days and the pollution is serious. To improve air quality, there must be cold air or rain.

The above is just my humble opinion on the deterioration of air quality in Chengdu in autumn and winter. If there is anything inappropriate or incomplete, please correct me or supplement it completely.