What caused the sandstorm to be active?

Sandstorm is a disastrous weather phenomenon in which wind and sand interact. Its formation is closely related to the global greenhouse effect, El Nino phenomenon, forest decline, vegetation destruction, species extinction, climate anomaly and other factors. Among them, overexploitation of natural resources, excessive deforestation and excessive land reclamation caused by population expansion are the main reasons for frequent sandstorms.

As a kind of high-intensity sandstorm disaster, sandstorms can not occur in all windy places, but only in those areas with dry climate and sparse vegetation. In the northwest of China, the forest coverage rate is not high, and the poor people in the northwest want to make a fortune by digging licorice, hugging seaweed and mining. These predatory acts of destruction have further aggravated the sandstorm disaster in this area. Exposed land is easily rolled up by strong winds to form sandstorms or even strong sandstorms.

after a large-scale sandstorm occurred in late winter and spring, the dust raised by strong winds caused a lot of dust in the air, which blocked the local sunshine and even made the visibility zero, so the super sandstorm was also called a black storm. Sandstorm will cause great losses to people's lives, property and agriculture. Sandstorms mainly originate in desertification areas, with soft soil, dry ground and no vegetation on the ground. Once the air is unstable in a large range and the ground wind speed is high, it is easy to blow up the surface dust and enter the air to form dusty weather.

After the sandstorm, the dust with larger particles is mostly behind the source or adjacent areas; That is, the particles with smaller particles can be transported upward to an altitude of 1 to 3 meters, and then transported eastward by the airflow in the westerly belt. In the process of transportation, part of the dust is diffused or diluted, which makes the dust farther away with the distance of transportation; The lower the concentration, the part will reach the ground under the action of settlement or rainfall (snow) during the transmission. The dust in the northwest of China can move eastward to Japan, South Korea and Hawaii, 1, kilometers away, and southward to Taiwan Province, Hongkong and even the Philippines, with a wide range of influence.

When sandstorms spread to other areas thousands of kilometers away, local visibility and suspended particles in the atmosphere increased, which affected the local air quality. As for the time or range affected by dust storms, it depends on the scale and duration of dust storms in the source area and whether the meteorological conditions in remote areas are favorable for dust transport. According to the observation records, the visibility is affected as short as several hours, and as long as one week, it even causes mud rain.

Dust weather can be divided into three categories: floating dust, sand blowing and sandstorm.

Floating dust is a weather phenomenon in which sand or soil particles suspended in the atmosphere make the horizontal visibility less than 1 kilometers.

Sand blowing: The wind blows up dust on the ground, making the air quite turbid, and the horizontal visibility is within 1-1 kilometers;

sandstorm: a weather phenomenon in which strong winds blow up dust and sand on the ground, making the air very turbid and the horizontal visibility is less than 1km; When the horizontal visibility is less than 5 meters, it is a strong sandstorm.

According to the research, the sand dust in the desert is the main source of suspended particles in the earth, and the sand dust in the Sahara desert alone accounts for 25% of the suspended particles in the global atmosphere. Northwest China is located in the desert area of Central Asia, ranking second among the four desert areas in the world (Central Africa, Central Asia, North America and Australia in turn), so the impact of dust in northwest China on the atmospheric environment of East Asia can not be ignored. The conditions for sandstorm occurrence are:

Surface properties: soft and dry soil, no vegetation or vegetation growth and no snow.

meteorological conditions: strong and persistent ground wind, vertically unstable meteorological conditions and no rainfall and snowfall.

The total area of deserts in the northwest of China is nearly 6, square kilometers, and the main sources are located in the northwest of China and the areas of North China and Mongolia, including Xinjiang, Gansu, Hetao, Inner Mongolia and Mongolia. The annual rainfall in this area is below 4mm, and the seasonal distribution is quite uneven, which is the main source of sandstorm weather in East Asia. Late winter and spring are the main seasons for sandstorms, with the highest frequency from March to May, accounting for more than 6% of the whole year, and the number of sandstorms varies every year.

The foreign source of dust that affects most parts of China and North China, especially the dusty weather in Beijing, is mainly Mongolia. However, the foreign dust sources that affect the dust weather in northern China are mainly located in the desertification zones in Kazakhstan and Russia.

The Mongolian vortex system is the main factor that affects the dust weather in eastern China. After the formation of the Mongolian vortex, the local dust is generally first rolled up and gradually moved south. In the process of moving, the ascending airflow at the tail of the vortex will drag the dust from the dust source along the way into the vortex and transport it downstream. Beijing is in the downwind area, and the deep vortex system often brings dusty weather to Beijing.

There are two main moving paths that affect the dusty weather in Beijing: North Road runs from the eastern and western regions of Mongolia, passing through the western Hunshandake Desert in Inner Mongolia, Huade and Zhangjiakou to Beijing; West Road starts from Hami City, Gansu Province to the border between China and Mongolia in Alashan League, Inner Mongolia, along Hexi Corridor, south of Helan Mountain, through Mu Us Desert and Wulanbuhe Desert, Hohhot City and Zhangjiakou, and finally reaches Beijing. Sandstorms that occur on the edge of Taklimakan Desert in Xinjiang will form long-distance transportation when they encounter strong systems crossing the border, which can affect Beijing area.

According to the frequency and intensity of sandstorms, the composition and distribution of sandstorms, ecological status, soil moisture content, water and soil utilization mode and intensity, combined with the regional environmental background, northern China is divided into four main sandstorm centers and source areas: 1. Hexi Corridor in Gansu Province and Alashan League in Inner Mongolia; 2. The surrounding area of Taklimakan Desert in southern Xinjiang; 3. The northern slope of Yinshan Mountain in Inner Mongolia and the adjacent area of Hunshandake Sandy Land; 4. Along the Great Wall of Mongolia, Shaanxi and Ningxia. The dust in the above-mentioned sandstorm-prone areas is often transported to North China and the middle and lower reaches of the Yangtze River with the westerly wind and northwest airflow, forming dusty weather.

frequent occurrence of sandstorms is one of the signs of ecological environment deterioration. The area of desert, Gobi and desertified land in China has reached 1.653 million square kilometers, and it is developing at the rate of 2,46 square kilometers per year. Land desertification is very different between the east and the west. Taking Helan Mountain as the boundary, the west is controlled by the arid climate in the northwest, and there is no rainfall. The land use is an oasis irrigated agricultural area. The main factors and manifestations of desertification are improper allocation of water resources, abandoned farmland in the lower reaches due to lack of water or blind reclamation, firewood harvesting and overgrazing in the transitional zone between desert and oasis, or natural vegetation death and increased wind erosion in grassland due to surface water depletion and groundwater level decline. Affected by the East Asian monsoon, there is a certain amount of precipitation in summer and autumn in the east. Desertification mainly occurs in the ecotone between agriculture and animal husbandry. In the dry season of winter and spring, it is caused by excessive reclamation, serious overgrazing and degradation of grassland, and firewood harvesting. The main forms are soil desertification, gravel, shrub desertification and sand activation in agricultural land. At the beginning of 2th century, the United States developed western land on a large scale, which led to the "black storm" that shocked the world in 193s. In the 196s, the land around Karakum Desert in Kazakhstan was reclaimed by the former Soviet Union, and there was also a strong sandstorm. After the 193s, the United States made great efforts to adjust the agricultural planting structure in the construction and transformation of the western region, adopting a set of effective methods, such as crop intercropping, interplanting and crop stubble at different maturity and sowing dates, vigorously promoting no-tillage method and reforming agricultural machinery. After the 196s, the former Soviet Union attached great importance to building water conservancy projects and vigorously building farmland shelterbelt networks in the construction and transformation of Central Asia, and achieved good results. It has provided the world with two different technical models to prevent and control sandstorms-agricultural measures (the United States) and forestry measures (the former Soviet Union). We should learn from the successful experience of other sandstorm-prone areas in the world and formulate ecological restoration strategies and policies suitable for China's national conditions.

Sandstorm is the product of the interaction of weather process and ground process. However, at present, the ability of human beings to control the weather is still very limited. The key to slow down the frequency and intensity of sandstorms lies in the ecological protection and construction of the ground. Adhere to the ecological protection and construction policy of "giving priority to prevention, giving priority to protection and paying equal attention to prevention and control"; Establish and improve the regulations and policy system of ecological protection, stop all production activities that lead to the continued deterioration of the ecological environment, and take certain ecological migration measures for areas beyond the ecological carrying capacity.

Sandstorms may induce allergic diseases, epidemics and infectious diseases. According to him, under normal circumstances, people's nasal cavity, lungs and other organs have a certain filtering effect on dust, but dust storms, a severe weather phenomenon, bring too much and too dense fine dust, which is very likely to make people with respiratory allergic diseases relapse. Even healthy people, if they inhale dust for a long time, will also have cough, asthma and other discomfort symptoms, leading to epidemic attacks. In addition, strong winds span thousands of kilometers, blowing germs along the way to downwind areas, which may include some infectious germs.

Dust is the most harmful to human respiratory system, and people should not underestimate it. In particular, the elderly, infants and people with respiratory allergic diseases with poor resistance should stay indoors with closed doors and windows, and stay away from dust sources as far as possible. Once you find that your body has obvious discomfort, you must immediately go to the hospital to find out the cause.

when you must be outdoors, it is best to protect your eyes and mouth with wet towels and gauze towels, but it needs to be reminded that this simple protection does not work against viruses. Before the dust storm recedes, construction workers and cleaning workers should temporarily stop outdoor operations. He also suggested that people drink more water, eat more light food and don't buy street open-air food.

We hope that sandstorms will disappear one day, but in fact this idea is almost impossible to realize. We can do some analysis on the formation conditions of sandstorms. There are three conditions for the formation of sandstorms. First, wind is the original driving force of sandstorms. Secondly, there is sand source. If there are no basic materials such as sand source and fine sand, there will be no sandstorm if there is atmospheric circulation. Thirdly, after the surface is heated (usually under dry conditions), an unstable updraft is generated, which takes the sand on the ground to the high altitude, thus forming sandstorms, which are the three main reasons for the formation of sandstorms. To ask when the sandstorm will end, we must first ask whether these three factors will end.

The Chinese Academy of Forestry has done some experiments to simulate the conditions of arid and semi-arid areas by using the observation data of more than 1 observation stations distributed throughout the country for 1 years. The results show that by 25, the arid areas in China are still expanding, and the sources of sandstorms will still exist. In addition, it is impossible for us to control global warming and atmospheric circulation. From this perspective, natural factors seem to play a leading role in the occurrence of sandstorms. However, we should see that there are many human activities that aggravate it. Sandstorm is a manifestation of land desertification and desertification. Although it is impossible to return to the state of "wind blowing grass and seeing cattle and sheep", we are not pessimistic. We can take measures such as returning farmland to forests and grasses, sand control projects, and shelterbelts in the Three North to reduce sand sources.

Objectively speaking, China's sandstorms can easily affect Japan, North Korea and other countries, but they certainly suffer much less than us. One of my Japanese colleagues once said that the dusty weather is not good, but it is not necessarily harmful when it really comes. We know that dust is rich in calcium, which can neutralize acidic substances such as sulfur dioxide, which is also beneficial to Japan, a country with frequent acid rain. Even if the dust doesn't have the strength to fly that far and falls into the sea halfway, it is also a rare nutrient for marine life. What are the reasons for the formation of sandstorms?

a: speaking of the reasons for the formation of sandstorms, there are many aspects. The driving force of sandstorm is wind. The material basis is dust. Wind and dust have complex and diverse temporal and spatial changes. There is a strong enough wind and a sufficient amount of dust. But blowing up a lot of dust also requires many conditions. Strong northwest wind prevails in the arid area of northwest China. Due to the uplift of the ancient Mediterranean, a large number of soft dust deposits were formed. Drought, little rain and sparse vegetation, especially drought, strong wind and sparse vegetation all occur simultaneously in spring, so there are natural conditions for sandstorms in spring, and human activities destroy the ground vegetation, which makes sandstorms more and more intense.

what are the fundamental ways to control sandstorms?

wind protection means afforestation. In fact, I share the upstairs view that sandstorms are mainly caused by soil erosion, and many kinds of trees can be stopped.

In recent years, the windy and dusty weather in China

According to statistics, there were 8 sandstorms in the 196s, 13 in the 197s, 14 in the 198s, and more than 2 in the 199s, and the scope of the sandstorm has become wider and wider, resulting in losses. The situation of several major gale and sandstorm weather in China since the 199s is introduced as follows: 1993: From April to early May, gale weather appeared in the north for many times. From April 19th to May 8th, Gansu, Ningxia and Inner Mongolia were successively attacked by strong winds and sandstorms. On May 5-6, a serious sandstorm hit eastern Xinjiang, Hexi in Gansu, most of Ningxia and western Inner Mongolia, causing serious losses. 1994: On April 6th, strong winds began to blow from Mongolia and the western part of Inner Mongolia, and the dust in the northern desert Gobi rose with the wind and floated over the Hexi Corridor, and the loess continued for several days. 1995: On November 7, more than 4 counties (cities) in Shandong were hit by a storm, with 35 people killed, 121 missing and 32 injured, resulting in direct economic losses of more than 1 billion yuan. 1996: From May 29th to 3th, the worst sandstorm swept the western part of Hexi Corridor since 1965. The black wind suddenly broke out, the world was closed, the dust filled, the trees collapsed, people had difficulty breathing, and the direct economic loss in Jiuquan area, which suffered the most, reached more than 2 million yuan. On April 5th, 1998, the central and western Inner Mongolia, southwest Ningxia and Hexi Corridor in Gansu were attacked by strong sandstorms, which affected a wide range, including Beijing, Jinan, Nanjing and Hangzhou. On April 19th, the TuTantuo Basin in northern and eastern Xinjiang was hit by a strong wind with an instantaneous wind force of 12, and some areas were accompanied by dust. The devastating typhoon caused a lot of property losses, with 6 people dead, 44 missing and 256 injured. In the early morning of May 19th, the northern part of Xinjiang was suddenly hit by a strong wind. The winds in the tuyere areas such as Alashankou and Tacheng reached 9-1, and the instantaneous wind speed reached 32 meters per second. The winds in other areas generally reached 6-7. The strong wind blew down trees and cut off power lines in some areas. 1999: From April 3rd to 4th, continuous gale and sandstorm occurred in Hohhot for two consecutive days. The sandstorm ranged from the western part of Inner Mongolia Autonomous Region to the southern part of Tongliao City in the east, with an instantaneous wind speed of 16 meters per second. The maximum wind force in Dalat Banner of Yikezhao League is 1. 2: From March 22 to 23, a large area of sandstorm weather occurred in Inner Mongolia Autonomous Region, and part of the sandstorm was carried over Beijing by strong winds, which aggravated the degree of sand blowing. On March 27th, the sandstorm hit Beijing again, and the instantaneous wind force in some areas reached 8-9. Seven workers who were working on the roof of a two-story building in Anxiangli Community were blown down by strong winds, and two of them died on the spot. Some billboards were blown down by strong winds, injuring pedestrians and damaging vehicles. 22: March 18th to 21st, the largest scale since 199s,