The strongest sandstorm weather has hit in the past decade. Why is this sandstorm so serious?

Recently, the news of the strongest sandstorm swept the major media, and its events included:

The dust from Mongolia entered our country, which had a serious impact on our country. There are many reasons. In March, the earth warmed up, the vegetation did not grow, the ice and snow melted, and the surface was bare. In the early stage, the temperature in Mongolia and northwest China was obviously high, generally 5-8℃, which was due to the melting of sand source snow and ice, sand? Active? It provides better auxiliary conditions. In addition, precipitation in most parts of Mongolia is relatively scarce recently, and the surface conditions are very favorable for sandstorms.

The Mongolian cyclone has strong transmission power, and the pressure gradient is large during the eastward movement, forming a strong wind. Abundant sand sources on the ground are blown into the sky and transported to the south under the action of high-altitude wind.

According to statistics, after entering March every year, the dusty weather in northern China enters a period of high incidence. The temperature rises rapidly in spring, and the northern sand source area begins to thaw. In addition, dust is difficult to suppress, which provides material conditions for the occurrence of dust. At the same time, at this time, cold air activities in the north are still frequent, and windy weather is frequent, which is easy to blow up the soil or sand on the surface, thus forming dusty weather.

What are the influencing factors?

1. Strong wind is the driving force of sandstorm, and dust source is the material basis of sandstorm. Unstable thermal conditions are conducive to the increase of wind power and the development of strong convection, thus carrying more dust and blowing higher. In addition, drought and lack of rain in the early stage, warming weather and rising temperature are the special weather and climate background for the formation of sandstorms.

2. The convective cells before the ground cold front develop into clouds or squall lines, which is a small and medium-scale system conducive to the development and strengthening of sandstorms; The topographic condition conducive to the increase of wind speed, that is, the narrow tube effect, is one of the favorable conditions for the formation of sandstorms.

Physical mechanism of sandstorm formation

3. Under the favorable large-scale environment, high-altitude dry and cold jet, strong vertical wind speed, wind shear and thermal instability stratification, the generation and development of small and medium-scale systems near the front area intensified the pressure and temperature gradient before and after the front area, forming a huge pressure and temperature gradient before and after the front area. Under the joint action of momentum downward transfer and gradient deviation wind, the wind speed in the near-surface layer rises sharply, causing dust on the surface and forming sandstorm or strong sandstorm weather.

Main hazards of sandstorm

(1) Strong wind: Strong wind accompanied by fine dust damages buildings and public facilities, causing death.

⑵ Sand burial: Farmland, channels, cottages, railways, grasslands, etc. are buried by a large number of quicksand in the form of quicksand, especially posing a serious threat to transportation.

⑶ Soil wind erosion: The dust source and affected area of each sandstorm will be harmed by wind erosion in different degrees, and the depth of wind erosion can reach 1 ~ 10 cm. It is estimated that the annual loss of soil fine matter caused by sandstorms in China is as high as 106 ~ 107 tons, most of which are below 10 micron, which seriously damages the land productivity of farmland and grassland in the source area.

⑷ Air pollution: In the source area and influence area of sandstorm, the inhalable particulate matter (TSP) in the atmosphere increases, and air pollution intensifies. ?

Dust storm prevention measures

1. Strengthen environmental protection and raise it to the height of legal system.

2. Restore vegetation, strengthen biological protection system and prevent sandstorms. Protect and restore forest and grass vegetation according to law, prevent further expansion of land desertification, and minimize dust sources.

3. According to the local conditions in different regions, formulate disaster prevention, disaster prevention and relief plans, actively promote various disaster reduction technologies, and build model projects, gradually promote them from point to area, and further improve the regional comprehensive defense system.

4. The long-term predatory exploitation of natural resources has caused serious damage to the natural ecological environment, and the deterioration of the environment has provided a rich source of dust for sandstorms.

5. Control population growth, reduce the pressure of human factors on land and protect the environment.

6. Strengthen the popular science propaganda on the relationship between the occurrence and harm of sandstorms and human activities, and make people realize that once the living environment is destroyed, it will be difficult to recover, which will not only aggravate natural disasters such as sandstorms, but also form a vicious circle, and people should consciously protect their living environment.