Dust absorbs some solar radiation. A moderate amount of dust in the air can absorb a little solar radiation of various wavelengths, which will reduce the intensity of solar radiation reaching the ground. Otherwise, the days of high temperature ≥35℃ in summer will increase.
Therefore, dust can adjust the surface temperature and make it more suitable for the survival and reproduction of life. However, if there is too much dust accumulation, it is necessary to prevent the ground long-wave radiation from radiating outward, resulting in a "greenhouse effect", warming the climate and causing a series of vicious cycles.
The role of dust
Without dust, clouds in the sky are difficult to form. Because clouds are composed of water droplets and ice crystals suspended in the air. Without dust, water vapor cannot condense. Dust is a kind of hygroscopic particle, which can play the role of condensation nucleus, so that the surrounding water vapor condenses on it, which is directly related to the formation of clouds and rain.
Without condensation, water vapor in the air is difficult to condense. Even if the air is saturated and the relative temperature reaches 300%~400%, it is still difficult to condense. But as long as some hygroscopic particles such as dust and smoke particles are added, the water vapor will condense immediately. These particles will adsorb water vapor on their surfaces and form embryos of water droplets, so they are called "condensation nuclei".
The radius of particles is generally between10.3-10.7 mm. The larger the particles, the stronger the adsorption of water vapor molecules, and the easier it is for water vapor molecules to gather on them. It is foggy over industrial areas and big cities, because there is more dust in the urban air.