Why is sandstorm called "natural enemy" of spring?

Sandstorm is a natural phenomenon with great destructive power. Sandstorm, also known as sandstorm or dust storm, refers to the weather phenomenon that strong winds blow up dust and sand on the ground and make the air very turbid, and the horizontal visibility is less than 1 km. When sandstorms appear, the yellow sand is rolling and the sky is dark, which is common in the afternoon in winter desert areas and dry loose soil that has been short of rain for a long time. Meteorologically, floating dust, sand blowing and sandstorm are collectively referred to as dusty weather, and the differences between them are mainly distinguished by visibility and wind power. Floating dust refers to sand grains or dust uniformly suspended in the atmosphere, and its horizontal visibility is less than 1 kilometers; Sand blowing refers to blowing up the sand on the ground to make the air quite turbid, and the horizontal visibility is between 1 km and 1 km; When the strong wind blows up the sand on the ground, it makes the sky turbid and the horizontal visibility is less than 1 km, which is called sandstorm; When the horizontal visibility is less than 5m, it is defined as a strong sandstorm.

Modern scientific and technological research on planting trees and improving the environment shows that the occurrence of sandstorms has a certain relationship with human activities, but the fundamental reason is natural factors. There are three main reasons: first, there are vast deserts in the north and northwest of China, and the northern region is rainy and dry, and the land is bare, which provides inexhaustible dust. Second, there is a Mongolian cyclone, which drags a lot of dust into the sky. Third, there is a cold air flow that carries the dust involved in the high altitude to the distance. Without one of these three conditions, it is difficult to form a large-scale sandstorm. In recent years, sandstorm weather has frequently attacked Beijing, seriously affecting people's lives. It is a manifestation of environmental deterioration and has also become a hot issue of public concern. In the rainy season of 22, the precipitation in northern China was more than that in the previous year, so the vegetation coverage was better, and the dusty weather in 23 was obviously reduced. 22 was a year of frequent dust storms in northern China, which even affected southern China and South Korea. Especially in 21, the drought was more serious, and Hebei, Tianjin, Inner Mongolia, Liaoning and other places were severely affected by the drought, which led to frequent sandstorms. When dusty weather occurs, you should try to reduce going out, and avoid inhaling too much polluted air in the case of serious pollution. If you go out, you should add more clothes to avoid catching cold.

As early as in ancient Chinese history books, there are records of sand-dust phenomena, such as "Yellow wind comes from the northwest, uprooting trees and building houses", "flying sand is like rain", and in the fourth year of Song Zhenzong Tianxi (12), "Dinghai in April, strong wind rises from the northwest, flying sand breaks trees, and the days are dark for several hours, and in May, the storm starts to sound in the northwest, and loess covers the sky", which describes spring. People commonly call it "sandstorm", "yellow wind" or "black storm". Dust weather not only exists in China, but also occurs in many countries in the world.

There are four high-risk areas of sandstorms in the world: Central Asia, North America, Central Africa and Australia. Northwest China is an integral part of the high incidence area of sandstorms in Central Asia, and the number of sandstorm days in many areas is more than 3 days per year. The "black storm" in the United States and Canada in the 193s is a typical example. On May 12, 1934, the sandstorm was 24 kilometers long from east to west and 4 kilometers wide from north to south, sweeping almost two-thirds of the territory. About 3 million tons of topsoil was blown from the west coast to the northeast coast, which led to a serious reduction in winter wheat production in the United States, which was 5.2 billion kilograms less than that in the past 1 years. At that time, the "black storm" dealt a devastating blow to American agriculture, brought endless troubles to American society and people's lives, and caused unprecedented serious damage to the ecological environment.

Sandstorm is not without its merits. The large amount of dust it carries can inhibit acid rain in northern China, and it can also significantly inhibit acid rain in South Korea and Japan.

At present, the preliminary project of Beijing sandstorm monitoring and early warning service system has been successfully implemented. Among them, equipment such as solar photometer and aerosol monitor will continuously record basic data such as particle size, mineral composition, chemical composition and occurrence intensity of dust. It can effectively monitor and accurately warn the harm and influence caused by sandstorm.