Why can high temperature days in summer reduce the concentration of pollutants?

In the troposphere, the temperature decreases with the elevation, with an average increase of 100 m, and the temperature decreases by about 0.65℃. The reason why the temperature decreases with the increase of altitude is that the main heat source of troposphere atmosphere is ground long-wave radiation. The higher off the ground, the less heated and the lower the temperature. However, under certain conditions, the temperature in the troposphere will also increase with the increase of height, which is the so-called "inversion phenomenon". Due to the great influence of the surface, the horizontal distribution of meteorological elements (temperature, humidity, etc.). ) uneven. The regular vertical movement of air and the irregular turbulence are quite intense. The water vapor, dust and heat in the upper and lower layers are exchanged and mixed. Because more than 90% of water vapor is concentrated in the troposphere, many weather phenomena such as clouds, fog, rain and snow occur in the troposphere.

The reason why the stratosphere is contrary to the troposphere, and the temperature rises with the increase of height is because its bottom absorbs the ultraviolet rays of the sun and is heated. So on this floor, the temperature will rise because of the height. The temperature at the top of the stratosphere hovers around 270K, which is similar to the ground temperature. The top of the stratosphere is called the stratosphere top. Above the stratosphere top, the temperature will drop again with the height. As for vertical temperature stratification, the stratosphere is relatively stable because the high temperature layer is above and the low temperature layer is below. This is because there is no traditional convection activity and connected airflow. This layer is warming because the ozone layer absorbs the ultraviolet rays of the sun, thus heating the top of the stratosphere. As for the bottom of the stratosphere, the conduction from the top and the convection in the lower troposphere cancel each other out just there.