The diameter of dust particles is generally between one ten thousandth and one millionth of a millimeter. The dust that the human eye can see is a giant in the dust, and the tiny dust can only be seen under a high-power microscope. The main sources of dust are soil and rocks. After weathering, they split into fine particles. These particles float in the air with other organic particles.
Dust will absorb some sunlight and reflect it around, just like countless point light sources. The sunlight is greatly weakened by the reflection of dust, so it becomes soft. If there is no dust in the atmosphere, strong sunlight will make people unable to open their eyes.
Interestingly, dust particles also have a "strange temper", which tends to reflect purple, blue and cyan light with shorter wavelengths, and "likes" to absorb other colors with longer wavelengths. The sky we see on the ground is blue because of the high dust content in the lower atmosphere. If there were no dust in the atmosphere, the sky would be white.
Most dust is hygroscopic. Water vapor in the air must adhere to dust to condense into small water droplets. In this way, when the water vapor in the air reaches saturation, the dispersed water vapor will adhere? Dust forms stable water droplets that can float in the air for a long time. If there is no dust in the air, everything on the ground will be wet. What's more, there can be no clouds in the sky, and it is impossible to form rain and snow to adjust the climate, so it is impossible for water evaporated from the ground to return to the ground. If there is less and less water on the earth and it dries up completely, living things can't survive. In addition, due to the refraction of these small water droplets to the sun's light, there will be sunset glow, morning glow, idle clouds, rainbow halo and other colorful natural scenery. If there were no dust in the air, how monotonous nature would be!
The role of dust tells us that everything has its two sides.