Popular science knowledge handwritten newspaper materials

Dust is annoying to everyone, and it is harmful to the environment? Health is harmful to human health. Therefore, throughout the ages, people have always been "diligent, not dusty." However, have you ever thought that human beings can't live without dust? If there is really no dust in nature, what kind of situation will we face?

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. They 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 two sides, and some of them are even

What people regard as "waste" often has its existence value that cannot be ignored. Only by correctly understanding them can we seek advantages and avoid disadvantages and benefit mankind.

Is this it?

Or this one below.

Fine dry powder particles of soil or other substances; Something reduced to tiny parts; Fine powder.

Dust is the enemy of human health, so people especially hate it, because it carries many bacteria, viruses and eggs everywhere and spreads diseases. Industrial dust and fiber dust can make workers suffer from various incurable occupational diseases. Excessive dust will also cause environmental pollution, affect people's normal life and work, and induce human respiratory diseases.

However, the contribution of dust can never be erased. If there is no dust in the atmosphere, sunlight will not be absorbed, reflected, scattered and refracted, and the sky will be either too bright or too dark. Because dust is a hygroscopic particle, without its core, water vapor in the air can't condense and clouds in the sky can't form. Without the cover of clouds, the surface will become dry and barren, and the weather will be either too hot or too cold. Without dust, many harmful rays in the universe will break into the earth's surface without hindrance, posing a fatal threat to human beings and all kinds of creatures.

Although Dust has many shortcomings, its contribution is endless. It can make the earth get solar energy gently, and it can also make enough condensation nuclei in the atmosphere, increasing the chances of cloud and rain formation. Adjust the surface temperature to make it suitable for the survival and reproduction of life.