What is the cause of sandstorm? What are the disadvantages?

The cause of sandstorm weather is favorable for windy or windy weather situation. Favorable dust source distribution and favorable air instability conditions are the main reasons for the formation of dust storms or strong dust storms. Strong wind is the driving force of sandstorm, and the source of sandstorm 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 winding it 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; The convective cells before the ground cold front develop into clouds or squall lines, which is a small and medium-sized 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. The physical mechanism of sandstorm formation, under the extremely favorable large-scale environment, high-altitude dry and cold jet, strong vertical wind speed, wind direction shear and thermal instability stratification, causes the formation and development of small and medium-scale systems near the front area, intensifies the pressure and temperature gradients before and after the front area, and forms huge pressure and temperature gradients 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 hazard of sandstorm (1) Strong wind: Strong wind accompanied by fine dust destroys 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. Taking 1993 "5.5" sandstorm as an example, the outdoor air TSP concentration in Jinchang, Gansu Province reached 10 16 mg/m3, and the indoor air TSP concentration was 80 mg/m3, exceeding the standard by 40 times. From March to April, 2000, Beijing was affected by sandstorms, and the number of days when the air pollution index reached Grade 4 or above was 10, which also affected many cities in eastern China. From March 24th to 30th, the daily pollution index of Nanjing, Hangzhou and other cities 18 exceeded Grade IV. Hazards of Sandstorm Weather Sandstorm weather is a disastrous weather in northwest China and northern North China, which can cause houses to collapse, traffic power supply to be blocked or interrupted, fires, casualties and so on. It pollutes the natural environment, destroys the growth of crops and causes serious losses and great harm to the national economic construction and the safety of people's lives and property. The hazards of sandstorms are mainly in the following aspects: 1. The ecological environment has deteriorated. When sandstorms occur, there are dust and floating dust wrapped in strong winds everywhere, and the number of people passing through areas with air turbidity, choking nose and eyes, respiratory diseases and other diseases increases. For example,1A serious sandstorm occurred in Jinchang on May 5, 993. The dust content in outdoor air is 10 16 mm/cm3, and the dust content in indoor air is 80 mm/cm3, which is 40 times higher than the national standard for dust content in living quarters. 2. Production and life are affected. A lot of dust carried by sandstorm weather blocked the sun, and the weather was gloomy, which led to the decrease of solar radiation. A few hours to ten hours of poor visibility can easily make people feel depressed and reduce the efficiency of work and study. In light cases, a large number of livestock can be infected with respiratory and gastrointestinal diseases, and in severe cases, a large number of "spring-deficient" livestock will die, and fertile soil, seeds and seedlings in farmland will be scraped away. Sandstorm will also aggravate the wind erosion and desertification of the surface soil, cover thick dust on the leaves of plants, affect normal photosynthesis and cause crop yield reduction. 3. Loss of life and property1993 On May 5, 2003, severe sandstorms occurred in Jinchang, Wei Wu, Minqin, Baiyin and other cities in Gansu Province, affecting 2,535,500 mu of farmland, losing 42,800 trees, resulting in a direct economic loss of 236 million yuan, 50 deaths and serious injuries 153 people. On April 12, 2000, strong sandstorms occurred in Yongchang, Jinchang, Wei Wu and Minqin. According to incomplete statistics, the direct economic losses of Jinchang and Wei Wu alone amounted to15.34 million yuan. 4. Traffic safety (traffic accidents such as airplanes and automobiles) Sandstorm weather often affects traffic safety, resulting in airplanes not taking off or landing normally, and cars and train carriages breaking, stopping or derailing. According to Xinhua News Agency, Lanzhou Electric Power Co., Ltd., with the efforts of experts from the Institute of Environment and Engineering in Cold and Arid Regions of Chinese Academy of Sciences, recently successfully completed a sandstorm wind tunnel simulation experiment specially designed to explore the mechanism of sandstorm start-up and propagation. Experts found through experiments that soil wind erosion is the primary link in the occurrence and development of sandstorms. Wind is the most direct driving force of soil, among which the nature of airflow, the magnitude of wind speed and the related conditions of wind action in soil wind erosion are the most important factors. In addition, soil water content is also one of the important reasons that affect soil wind erosion.