I believe that everyone has this experience. The haze is more serious in winter. Once winter comes, there is a pungent smell in the air, which makes people very disgusted. So why is the haze the most serious in winter? Do you know why? Today's editor will come to popularize science for you.
There are two main reasons for the serious haze in winter, one is the climate characteristics, the other is the heating. In detail, it is reflected in the following points:
1. Poor air mobility in winter
In autumn and winter, the air mobility near the formation will be weaker, and the pollutants will accumulate easily and spread unfavorably. Generally speaking, there are four ways of pollutant diffusion: atmospheric turbulence (irregular movement of air micro cluster), convection diffusion, advection diffusion and strong weather activities (such as precipitation, gale, etc.). However, in autumn and winter, the above-mentioned four ways of diffusion have been reduced, and they can not be spread out for a while.
2. Cold air activity is decreasing in winter
Autumn and winter are the seasons with frequent cold air activities, which are not conducive to the occurrence of fog and haze. However, in recent years, with the decrease of cold air process in autumn and winter, global warming is also an important reason for the frequent occurrence of fog and haze in China. Since 1961, the cold air process has been decreasing in winter and autumn.
3. There is less precipitation in winter
Precipitation and snowfall can clear and wash the fog and haze in the atmosphere. Therefore, more precipitation in summer is not conducive to the occurrence of fog and haze, while less precipitation in autumn and winter is conducive to the occurrence of fog and haze. Statistics show that the number of precipitation days in autumn and winter has decreased since 1961.
4. Low air humidity in winter
When haze occurs, the weather conditions are characterized by stable and dry air mass, and there are many days when such weather conditions are met in autumn and winter. It is found that the humidity in autumn and winter is small, and in the past 50 years, the autumn shows a significant downward trend, and the autumn and winter show more and more dry signs, which is conducive to the increase of haze days and the decrease of fog days.
5. The inversion layer is easy to appear in winter
In winter, because of the obvious radiation cooling at night on the ground, the inversion layer is easy to appear in the low altitude of the atmosphere, and the atmosphere is in a static and stable state, which makes the pollutants unable to diffuse. The horizontal and vertical exchange and circulation capacity of the air becomes weak, and the pollutants discharged in the air are limited in the shallow atmosphere, and gradually gather into haze, resulting in air pollution.
At the same time, the frequency of fog days in winter is more, because the winter night is long, the chance of small wind in sunny days is more, the ground heat dissipation is faster, and the temperature drops more significantly. When the temperature drops to the lowest in the morning, the water vapor in the air is easy to reach saturation, condense into small water droplets, and the more small water droplets accumulate, the fog will be formed.
6. There is a lot of exhaust gas from heating in winter
The exhaust gas produced by heating coal in winter in the north. Affected by heating and so on, more pollutants are discharged in winter, which is also an important reason for the occurrence of smog days in winter. In winter, a large number of coal-fired, a large number of smoke and waste heat are released, and the temperature inversion occurs in the vertical direction of the atmosphere, which limits the vertical movement of the air in the low altitude of the atmosphere, makes the atmosphere more stable and unfavorable and the diffusion of pollutants. For haze weather, pollutant emission is the "culprit", and adverse meteorological diffusion conditions are the "accomplice". The fundamental way to solve air pollution is to reduce pollution emissions and green the environment.
In particular, the higher the buildings are built in the city, the blocking and friction effect makes the wind flow weaken obviously when passing through the city. The increase of calm wind is not conducive to the diffusion and dilution of aerosols in the atmosphere, and it is easy to accumulate around urban and suburban areas; the increase of aerosols in the air. With the growth of urban population, industrial development and the sharp increase of motor vehicles, the emission of pollutants and suspended solids increase greatly, which directly leads to the reduction of visibility. So it is easy to appear haze in winter.