How terrible is the sandstorm?

Sandstorm is a general term for sandstorm and sandstorm. It refers to a severe sandstorm weather phenomenon in which strong winds blow a large amount of sand and dust substances into the air, making the air particularly turbid and the horizontal visibility less than 1 km. Among them, sandstorm refers to a sand-laden storm formed by strong wind blowing a large amount of sand near the stratum; Sandstorm is a storm formed by strong winds, which brings a lot of dust and other particles into the sky.

Globally, sandstorms mostly occur in inland desert areas, mainly the Sahara desert in Africa, and the midwest of North America and Australia are also one of the sources of sandstorms. From 1933 to 1937, the famous bowl-shaped sandstorm occurred in the midwest of North America due to severe drought. Asian sandstorm activity centers are mainly located in the Jordanian desert, Lower Mesopotamia between Baghdad and the northern coast of the Gulf, the southern Iranian coast near Abbas and the northern Afghan plain. Kazakhstan, Uzbekistan and Turkmenistan in Central Asia of the Soviet Union are all affected by frequent sandstorms (≥ 15 times/year), but their centers are all on the sandy plain between Caspian Sea and Aral Sea and Amu Darya River.

Due to its unique geographical environment, the northwest of China is also a region where sandstorms frequently occur. The main source areas are Gurbantunggut Desert, Taklimakan Desert, Badain Jaran Desert, Tengger Desert, Wulanbuhe Desert and Mu Us Desert. So, how did the terrible weather like sandstorm form? What's the harm? What preventive measures are there? Let's have a good understanding of the causes of this bad weather: the weather situation favorable to strong winds or strong winds, favorable distribution of dust sources and favorable air instability conditions are the main reasons for the formation of sandstorms or strong sandstorms. 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.

Physical mechanism: Under the favorable large-scale environment, high-altitude dry and cold jet, strong vertical wind speed, wind direction shear and thermal instability stratification, the generation and development of small and medium-sized 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.

Sandstorm has caused serious losses and great harm to national economic construction and people's lives and property safety. The hazards of sandstorms mainly include the following aspects:

. When the ecological environment deteriorates and sandstorms occur, dust and floating dust carried by strong winds are everywhere, and the number of people suffering from respiratory diseases and other diseases increases in areas with turbid air. 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.

. 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 surface soil, and the thick dust covering plant leaves will affect the normal photosynthesis of plants and cause crop yield reduction.

. Loss of Life and Property On May 5, 2008, severe sandstorms occurred in Jinchang, Wei Wu, Minqin, Baiyin and other places in Gansu Province, affecting 2,535,500 mu of farmland, losing 42,800 trees, resulting in direct economic loss of 236 million yuan, 50 deaths and serious injuries 153. 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.

. 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 being damaged, stopped or derailed.

Although there are many hazards of sandstorm, the whole process of sandstorm is also an indispensable part of natural ecosystem. What's going on here? For example, a large amount of iron captured in the red sandstorm in Australia has been proved to be an important nutrient source for plankton in the Antarctic Sea. Phytoplankton can consume a large amount of carbon dioxide to mitigate the harm of greenhouse effect, so the impact of sandstorms is not all negative.

Perhaps on another level, sandstorms may also be a symptom of the earth's response to environmental changes, just as we cough when we have a cold to remove waste from the trachea. Many climatologists gathered in Australia to study the nutrients provided by sandstorms in tasman sea and many other impacts. They found that the red seasonal sediments in Australian sandstorms can also be found in New Zealand, which also enriched the land of New Zealand. Therefore, nutrient loss caused by dust storms in Australia will lead to nutrient harvesting in New Zealand. As for the fertile soil deposits in Hawaii, according to the analysis data, it can be proved that many nutrients also come from distant Eurasia. Just because the two places are separated from Wan Li, it is impossible for ordinary winds to blow inland dust so far. Therefore, it is the sandstorm that carries tiny dust containing nutrients to an altitude of 3000 meters, crosses the ocean and spreads them like seeds.

Scientists have also found that in addition to the Hawaiian Islands, the rain forest in the Amazon basin, the largest green lung on earth, also benefits from sandstorms, and an important source of its nutrients is dust in the air. The secret that sandstorms can make the rocks lush is that the dust aerosol contains iron ions and other ingredients that help plants grow. In addition, because sandstorms are mostly born in dry and high saline-alkali land, some soil particles carried by sandstorms often contain some alkaline substances, so they can often slow down acid rain or soil acidification in the settlement area near sandstorms.

Mr. Wang Zifa of lasg once said, "Sandstorms really reduce the acidity of acid rain. The neutralization of sand dust and its soil particles increased the pH value of precipitation in northern China, South Korea and Japan by 0.8 ~ 2.5, 0.5 ~ 0.8 and 0.2 ~ 0.5 respectively. If there is no dust, then the harm of acid rain in many parts of the north is much more serious. " Therefore, although sandstorm is very harmful, it is also a necessary process in the natural ecology of the earth, because sandstorm has appeared since the beginning of human history. Only by actively looking for the mechanism of abnormal frequency of sandstorms can we really solve the harm of abnormal climate change to the environment.