Causes of sandstorm formation

situation

The weather situation favorable to strong winds or strong winds, favorable distribution of dust sources and favorable air instability conditions are sandstorms or sandstorms in Gobi desert accompanied by strong sandstorms.

The main reason for success. 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 main component of soil and yellow sand is silicate. When there is less rain and the air temperature becomes warmer, the silicic acid on the silicate surface loses moisture, and H2SiO4=SiO3 -2+H2O (gas) = In this way, the surface of silicate soil micelles and sand particles will be negatively charged, repel each other, become aerosols, and cannot be gathered together, thus forming sand blowing, that is, sandstorms. Sandstorms are essentially silicate aerosols with negative charges. In short, the formation of sandstorms needs these three conditions: first, the dust material on the ground. It is the material basis for the formation of sandstorms. The second is the strong wind. This is the dynamic basis for the formation of sandstorms and the dynamic guarantee for the long-distance transportation of sandstorms. Third, the air state is unstable. This is an important local thermal condition. Sandstorms often occur in the afternoon and evening, which shows the importance of local thermal conditions.

Dust weather is divided into four categories: floating dust, sand blowing, sandstorm and strong sandstorm. Floating dust: a weather phenomenon in which dust and fine sand float evenly in the air, making the horizontal visibility less than 10 km; Sand blowing: a weather phenomenon in which the wind blows up dust on the ground, making the air quite turbid and the horizontal visibility is within the range of 1 km to1km; Sandstorm: a weather phenomenon in which strong winds blow up a lot of dust on the ground, making the air very turbid and the horizontal visibility is less than 1 km; Strong sandstorm: a weather phenomenon in which strong winds blow up dust on the ground, making the air fuzzy and turbid, and the horizontal visibility is less than 500 meters.

Divide by process

Sandstorm weather process can be divided into four categories: floating dust weather process, sand blowing weather process, sandstorm weather process and strong sandstorm weather process. Floating dust weather process: in the same weather process, at the same observation time, floating dust weather occurred in five or more countries in China weather forecast area; Sand blowing weather process: In the same weather process and the same observation time, sand blowing weather occurs in five or more countries in China weather forecast area; Sandstorm weather process: in the same weather process, sandstorms occurred in three or more countries in China weather forecast area at the same observation time; Strong sandstorm weather process: In the same weather process, three or more countries in China weather forecast area basically (quasi) stood at the same observation time and experienced strong sandstorm weather.

Publishing standard

NO 1。 When the decision-making service predicts the sandstorm weather process in the next 24 hours, it will publish the sandstorm weather forecast in internal bulletins, special reports and decision-making service materials. NO2。 National standard for public forecast: it is expected that there will be a sandstorm weather process in the next 24 hours, and when it has a great impact or affects Beijing and Tianjin, it will issue a sandstorm warning to the public. ; It is expected that there will be a sandstorm or strong sandstorm weather process in the next 24 hours, which will cause serious impact and issue a sandstorm warning to the public. Provincial standards: determined by the provincial meteorological bureau with reference to national standards. Note: 1. The release standard of provincial sandstorm weather forecast and early warning is reported to China Meteorological Bureau for the record. 2. The forecast and early warning of sandstorm weather shall include the area, time, intensity, possible impacts and countermeasures of sandstorm weather. 3. The Central Meteorological Observatory shall promptly and effectively notify the relevant provincial meteorological stations before releasing the forecast and warning of dust weather to the society, and the provincial meteorological stations shall promptly and effectively notify the Central Meteorological Observatory and the relevant meteorological stations before releasing the forecast and warning of dust weather to the society.

Edit the appearance of this paragraph.

1The sandstorm wall stands on the mainland. Most strong sandstorms come from the northwest or west, and a few from the east. When almost all sandstorms come, we can see a black sand wall moving rapidly and getting closer and closer in the direction of the wind. Seen from a distance, the sandstorm wall is towering like a mountain, much like a city wall, and it is the sandstorm Depth Charge. 2. When a strong sandstorm occurs in the dark, it is very strong because the strong wind of magnitude 8 or above can roll up stones and sand. As more and more dust flies into the air, the thick dust is overwhelming, blocking the sun and making people see nothing for a period of time, just like at night. 3. When the black wind blows, the air near the ground is very unstable, the heated air below rises, and the surrounding air flows to supplement it, which causes the air to roll up and down with a lot of dust, forming countless dust clouds of different sizes to meet in the air. 4. The upper layer of colored sand wall is often yellow to red, the middle layer is gray-black and the lower layer is black. The reason why the upper layer is yellow-red is because the dust on the upper layer is so thin that sunlight can almost shoot down through the dust. The dust in the lower layer has a large concentration and coarse particles, and the sunlight is almost completely absorbed or scattered by the dust, so it is black. Where the sand wall has moved, the sky is flickering and changing. This is caused by light passing through dust belts of different thickness and consistency.

Edit this paragraph level

Sandstorm intensity is divided into four levels: 1, and level 4 ≤ wind speed ≤ 6,500 m ≤ visibility ≤ 1000m, which is called weak sandstorm; 2, 6 ≤ wind speed ≤ 8,200 meters ≤ visibility ≤500 meters, which is called medium-intensity sandstorm; 3, the wind speed is greater than 9, and the visibility below 50 meters is less than 200 meters, which is called a strong sandstorm; 4. When it reaches its maximum intensity (instantaneous maximum wind speed ≥ 25m/s, visibility ≤ 50m, or even reduced to 0m), it is called a particularly strong sandstorm (or black storm, commonly known as "black wind").

Edit this section of danger

principle

There are two main hazards of black wind, one is wind and the other is sand. There are two hazards of strong winds: one is wind damage, and the other is scraping the ground. Very strong. Let's talk about the typhoon first. Strong winds destroy buildings, blow down or pull up tree stems, tear up farmers' plastic greenhouses and farmland plastic films, and so on. In addition, April and May in northwest China are the time when cash crops such as melons, fruits, vegetables, beets and cotton emerge, cotyledons or true leaves grow, and fruit trees bloom, at this time, they are least resistant to sandstorms. Light leaves are covered with dust, which weakens photosynthesis, affects respiration and reduces crop yield; In the worst case, the seedlings will die, not to mention the mature results. For example, the black wind on May 5, 1993/kloc-0 caused 85,000 pistils of fruit trees to be destroyed in northwest China, and 109400 shelterbelts and timber forests were broken or uprooted. In addition, the strong wind blew down the telephone poles, causing water and electricity cuts and affecting industrial and agricultural production. 1On May 5, 993, the black wind caused power failure and water cut, and Jinchang Jinchuan Company alone caused economic losses of 83 million yuan. When strong wind acts on loose soil in arid areas, it will scrape off a layer of topsoil, which is called wind erosion. For example,1May 5, 1993, the average wind erosion depth of black wind 10 cm (up to 50 cm), that is, an average of 60 to 70 cubic meters of fertile topsoil per mu was blown away by the wind. In fact, strong winds not only blow away the fine clay and organic matter in the soil, but also pile up the sand in the soil, which greatly reduces the fertility of the soil. In addition, the strong wind with sand will wear off a layer of buildings and crops, which is called abrasion and also a disaster. The harm of sand is mainly sand burial. As mentioned above, in narrow pipelines, windward and uplifted terrain, due to high wind speed, the wind-blown sand hazard is mainly wind erosion, while in leeward depressions and other terrain with low wind speed, the wind-blown sand hazard is mainly sand burial. For example,1May 5, 993, where sand burial occurred in the black wind, the average thickness of sand burial was 20 cm, and the thickest part reached 1.2 m, more importantly, the loss of life. For example,1May 5, 993, 85 people were killed, 264 people were injured and 3 1 person was missing. In addition, the death loss of large livestock was 1.2 million, the crops were affected by 5.6 million mu, the total length of the lifeline canal buried by sand in arid areas was more than 2,000 kilometers, and the Lanzhou-Xinjiang railway was stopped for 3 1 hour. The total economic loss exceeded 540 million yuan. Sandstorm is a disastrous weather phenomenon in which wind and sand interact. Its formation is closely related to global greenhouse effect, El Nino phenomenon, forest decline, vegetation destruction, species extinction, climate anomaly and other factors. Among them, excessive exploitation of natural resources, excessive deforestation and excessive land reclamation caused by population expansion are the main reasons for frequent sandstorms. Therefore, we need to reduce land reclamation.

way

⑴ Strong wind: Strong wind accompanied by dust damages buildings and public facilities, causing human and animal casualties. 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 particles 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, respirable particulate matter (TSP) in the atmosphere increases sandstorm.

Air pollution has intensified. 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 reached 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.

result

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, human and animal casualties and so on. Pollution of the natural environment, destruction of crop growth and sandstorms.

It has caused serious losses and great harm to the national economic construction and the safety of people's lives and property. The harm of sandstorm mainly lies in the following aspects: when the ecological environment deteriorates and sandstorm weather occurs, there are dust and floating dust wrapped in strong winds everywhere, and people passing through this area are turbid, choking nose and eyes, respiratory diseases and other diseases increase. 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 the surface soil, cover thick dust on the leaves of plants, affect normal photosynthesis and cause crop yield reduction. Sandstorms also caused the temperature to drop sharply. The sky is like a parasol, and the ground becomes dark and cold in the shadow. Loss of life and property 65438+1May 5, 993. Strong sandstorms occurred in Jinchang, Wuwei, Minqin, Baiyin and other places 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. 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. Impact on Traffic Safety Impact on Traffic Safety (traffic accidents such as airplanes, trains and automobiles) Sandstorm weather often affects traffic safety, causing airplanes to fail to take off or land normally, causing cars and train carriages to be damaged, stopped or derailed. Harm to human health When people are exposed to dusty weather, dust containing various toxic chemicals and germs can enter the mouth, nose, eyes and ears through layers of protection. If the dust containing a lot of harmful substances is not cleaned in time, it will cause damage to these organs or bacteria will take these organs as invasion points, causing various diseases.

Edit the function of this paragraph

A terrible sandstorm

Although there are many hazards of sandstorm, the whole process of sandstorm is also an indispensable part of natural ecosystem. For example, a large amount of iron contained 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 sandstorm 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 from Australian sandstorms can also be found in New Zealand, which enriched the land of New Zealand. Therefore, nutrient loss caused by dust storms in Australia will lead to nutrient harvesting in New Zealand. For example, the fertile soil sediments in Hawaii can also prove 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. So it is the sandstorm that brings tiny dust containing nutrients to an altitude of 3000 meters, crosses the ocean, and then spreads them, which will generally disperse them. In addition to Hawaii, scientists also found that the rain forest in the Amazon basin, the largest green lung on earth, also benefited from sandstorms, and an important source of its nutrients was 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. Sandstorm is composed of silicate with negative charge, which can neutralize hydrogen ions in acid rain and reduce the harm of acid rain. However, few people know that sandstorms are not "harmful". On the one hand, sandstorms are beneficial to human beings, except that the Loess Plateau is recognized as being made. Alkaline sandstorms can neutralize acidic substances in the air after entering the atmosphere, thus achieving the effect of inhibiting acid rain. Now scientists have calculated the impact of dust storms on acid rain, that is, the neutralization of dust and soil particles increases the precipitation PH value by 0. 18 ~ 2. 15 in northern China, 0. 15 ~ 0. 18 in South Korea and 0.12 ~ in Japan. In addition, the nutrients it takes away from the desert fall into the ocean, providing sufficient nutrition for fish. " Sandstorms also do good deeds. But on the whole, sandstorms do more harm than good. [3] SiO3 2-+2 H+ = H2SiO3↓ The neutralization of sand dust and its soil particles increased the precipitation PH values in northern China, South Korea and Japan by 0.8-2.5, 0.5-0.8 and 0.2-0.5 respectively. If there were no dust, the harm of acid rain in many areas in the north would be much more serious. Therefore, although sandstorms are very harmful, they are also a necessary process in the natural ecology of the earth, because sandstorms have existed since 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.

Give it all to you ~ ~