Definition of floating dust

Floating dust is a weather phenomenon in which dust or soil particles are suspended in the atmosphere, making the horizontal visibility less than 10 km.

English name: dust: refers to the weather phenomenon that dust and fine sand float evenly in the air, making the sky khaki and the horizontal visibility less than 10 km.

Haze, light fog, sandstorm, sand blowing, floating dust, smoke and other weather phenomena are all due to a large number of extremely fine dust particles or smoke particles floating in the air, which makes the effective horizontal visibility less than 10KM. Sometimes it is difficult for meteorological professionals to tell the difference. We must analyze and judge the weather background, sky conditions, air humidity, color and smell, satellite monitoring and other factors in order to draw the correct conclusion that smog is also called atmospheric brown cloud. In the ground meteorological observation standard of China Meteorological Bureau, the definition of haze weather is: "A large number of extremely fine dry dust particles float in the air evenly, which makes the air with horizontal visibility less than 10 km generally turbid, and makes bright objects in the distance slightly yellow and red.

The weakest intensity is called floating dust weather, commonly known as "falling yellow sand" When it appears, the distant objects are khaki, the sun is pale or yellowish, the visibility is less than 10 km, and more than 1 km, and there is basically no obvious wind. Atmospheric particles with a diameter less than 10 micron are called floating dust and sandstorm, both of which are caused by violent activities of large airflow in a specific area. Its * * * characteristics are obviously reduced visibility and cloudy sky. It mostly happens when cold air passes through the border in northern spring, but the difference is that the visibility affected by sand blowing weather is between 1 km and 10 km. The visibility of sandstorm and windy weather is even less than 1 km. As a kind of high-intensity sandstorm disaster, sandstorm can't happen in all windy places, but only in those areas with dry climate and sparse vegetation. Sandstorms mostly occur in April-May every year. Take the northwest of China as an example. At this time of year, the Hawaiian high is formed in the Pacific Ocean, the Indian low is formed in the Asian continent, and the strong south wind blows from the ocean to the land. The Mongolian high, which controls the mainland, began to move westward and northward, where cold and warm air currents met, and the heavy Siberian cold current came rapidly from west to east, often forming strong winds. The wind force that forms sandstorms is generally above 8, and the wind speed is about 25 meters per second. In addition, the formation of sandstorms requires sufficient sand sources, and dust can be blown off the ground by the wind.