Why is inversion not conducive to the diffusion of air pollutants?

Under normal circumstances, the troposphere temperature is high near the ground, low at high altitude, the air near the ground rises and the air at high altitude sinks, forming convective motion, which will spread pollutants in the air.

However, when the troposphere near the ground temperature is low, the upper air temperature is high, or the rate of atmospheric temperature drop is lower than the vertical rate (the temperature drops by 0.6℃ for every vertical increase of 100m), the inversion phenomenon will occur. At this time, the atmospheric stratification is stable, and the air convection movement is weakened or stagnant, which is not conducive to the diffusion of atmospheric pollutants.

Extended data:

Positive influence of inversion temperature

1 can inhibit the occurrence of sandstorms, because the conditions for sandstorms are strong winds, dust and strong convection. ?

2. Inversion temperature appears at high altitude, which is extremely beneficial to aircraft flight. Because there will be no big bumps in the flight, the flight is smooth. At the same time, the clear skies in Wan Li have improved the visibility and made the flight safer.

3. It can be applied to grain planting to improve yield and quality.

negative impact

Main impact: air pollution. No matter what causes the inversion, it will have a great impact on air quality and hinder the vertical convection of air.

It hinders the diffusion of smoke, pollutants and water vapor condensate. Tens or even hundreds of meters thick inversion layer covers the city like a thick quilt. The pollutants near the ground have no way to go, so they have to "stay where they are". The more they accumulate, the thicker the smoke will be, covering the sky, and air pollution will inevitably increase. At the same time, air pollution poisoning incidents are mostly related to inversion.

If inversion occurs for several days, air pollutants will accumulate in large quantities, which is prone to air pollution poisoning. For example, in the industrial town of Donola in the United States, 1948+00, the temperature reversed for four consecutive days in June, and the air pollutants sulfur oxides and smog emitted by factories and residents could not spread in time, so that in this small town with only 14000 people, 5900 people fell ill and more than 20 people died within four days.

1952 The smog event in London, England was also related to fog and inversion. Smoke and sulfur dioxide emitted by factories and thousands of households stayed above the city, and 5000 people died in four days. The smog event in Mas Valley, Belgium, and the photochemical smog event in Los Angeles are all related to the inversion weather.

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