The basic reason for the formation of the smog area at the eastern foot of Taihang Mountain is the total amount of pollutants such as PM2.5 discharged into the air by human activities (automobile exhaust, enterprise exhaust and dust, etc.). ) There are too many of them. Take the urban area of Beijing as an example. After a northwest wind blows the air clean (the value of PM2.5 is below 50 points), the clean air can only last for about one day, because the value of PM2.5 pollutants added here is around 50-70 points every day. In this case, as long as there are 2-3 days of calm weather, Beijing urban area will enter a state of heavy pollution.
2. The high-rise buildings at the eastern foot of Taihang Mountain are an important factor for the quiet weather.
According to man-made terrain climatology, man-made tall buildings and huge buildings will change the climate of the local area, its surrounding areas and even distant areas to some extent. This is because tall buildings and huge buildings are essentially equivalent to new mountains and hills on the earth, which will increase the roughness of the surface and thus increase the wind resistance accordingly (the height range is 4-5 times that of buildings).
The water vapor preserved in Taihang Mountain is losing.
Taihang Mountain used to be a land of dense forests and abundant water, which was recorded in Shan Hai Jing and a large number of ancient books. Beishan Classic, the third mountain range in Wuzang Mountain Classic, describes the landform of Taihang Mountain 4,200 years ago. At that time, many water systems originated from Taihang Mountain, and there were many large lakes in North China Plain (refer to the huge painting of 42 square meters, such as Landscape of Sanguisorba, Classic Map of Mountains and Seas, Dictionary of Mountain and Seas Appreciation, decameron of Mountains and Seas, etc. ). Since then, because Beijing was the capital of the Yuan, Ming and Qing Dynasties, a large number of trees in Taihang Mountain have been cut down for building and heating, resulting in the destruction of the original forest vegetation here, and the amount of water flowing from Taihang Mountain to Bohai Sea has also decreased accordingly.
4. The evaporation of water vapor in Bohai Sea is decreasing.
Most of the water vapor preserved in Taihang Mountain comes from the evaporated water vapor in Bohai Sea, and the transporter is the east wind blowing from Bohai Sea. In addition, there is a small amount of water vapor from south wind, southeast wind, southwest wind and northeast wind. There is no doubt that the water resources around Bohai Sea mainly depend on the evaporation of water vapor in Bohai Sea. Therefore, once the evaporation of water vapor in the Bohai Sea is decreasing, it will inevitably lead to the decrease of water resources around the Bohai Sea. On the other hand, the decreasing trend of water resources around Bohai Sea indicates that the evaporation of water vapor in Bohai Sea is decreasing. The decrease of water vapor evaporation in Bohai Sea may also be one of the factors for the formation of the smog belt at the eastern foot of Taihang Mountain.