The smog problem in the north is more serious than that in the south. When is the foggy weather more serious in a day?

Smog weather is mainly composed of sulfur dioxide, nitrogen oxides and inhalable particles, especially in areas with relatively prosperous modernization, just as the smog problem in the north is much stronger than that in the south.

When is the worst smog in a day?

In the morning, that is, from 7: 00 to 8: 00, air pollutants began to increase rapidly, 10, and began to decrease in the evening, then returned to a lower value in the evening. This situation is closely related to the formula calculation mentioned above. Because of the water vapor in broad daylight and the action of the sun, the air pollutants discharged for the first time have secondary reflection and then accumulate rapidly. Moreover, people's theme activities also reach the peak in broad daylight, and the promotion and accumulation of waste gas emissions promote environmental pollution to reach the peak in the afternoon, while at night, because of the reduction of sunlight, secondary reflection is reduced, and pollution emissions are also reduced because of the reduction of people's theme activities, thus promoting environmental pollution to be alleviated. However, the smog curve in Beijing is different from the general environmental pollution curve. Environmental pollution usually reaches the highest value at night, but it is in the whole process of continuous accumulation in broad daylight. This also shows that environmental pollution in Beijing has its uniqueness.

How did the haze weather come about?

Undoubtedly, the ignition of non-renewable resources is the key source of PM2.5 in China. According to the statistics released by the environmental protection bureaus in Shanghai and Beijing, 40 ~ 75% of the heavy metals in PM2.5 components exceed the standard from the ignition of non-renewable resources, and more than 50% of the black carbon comes from the ignition of non-renewable resources. The main source of pollution emission in big cities is the burning of non-renewable resources such as raw coal and motor vehicles.

Haze usually forms in the early hours of the morning, so the concentration is the highest and the harm is the greatest in the morning.

The concentration level of PM2.5 is affected by pollution source emissions and meteorological conditions, and has obvious seasonal and time-varying characteristics. Although there are differences in specific values between the north and the south due to the daily and seasonal changes of humidity and temperature, the overall trend is roughly the same, that is, high in autumn and winter, low in summer, high in the morning and evening, and low in the afternoon.

Except for special weather, the concentration of PM2.5 is generally higher in the morning and evening, and the lowest in the afternoon. Generally speaking, 8:00- 10 every morning and 6:00-8:00 every night are the peak hours of commuting, and the massive emission of automobile exhaust is one of the reasons for the highest PM2.5 value in the air during these two periods.

In addition, it depends on the weather and diffusion conditions of the day. Inversion is very important in it. What is inversion? In general, the temperature decreases with the elevation, and the low-level air is hot and the high-level air is cold. The cold air will sink again, and the hot air will float slightly, thus forming convection.