Find out the causes of typhoons and sandstorms and their effects on human beings (disasters)

Typhoon is a strong storm that occurs in the tropical oceans of the northwest Pacific Ocean and the South China Sea. You must have seen a vortex appear in the river from time to time. In fact, a typhoon is an air vortex, which rotates around its center in the atmosphere and moves forward at the same time. It rotates counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. Meteorology calls the vortex in the atmosphere a cyclone, because the vortex in the typhoon atmosphere is produced on the surface of the tropical ocean, so it is called a tropical cyclone.

Why is it called typhoon? Some people say that in the past, people didn't understand that typhoons originated in the Pacific Ocean and thought that this huge storm came from Taiwan Province Province, so it was called a typhoon. Some people think that the typhoon hit Guangdong Province the hardest, and it evolved from Cantonese "gale".

In fact, almost all countries and regions located on the west coast of the ocean are affected by tropical marine cyclones, but people in different regions have given it different names.

Typhoons in the northwest Pacific and the South China Sea, hurricanes in the Atlantic Ocean, the Caribbean Sea, the Gulf of Mexico and the East Pacific, tropical storms in the Indian Ocean and the Bay of Bengal, and tropical cyclones in Australia.

B. Naming and numbering of typhoons

The naming, definition, classification and determination of the center position of tropical cyclones are different in different countries and methods, even in the same country, they are not exactly the same among different meteorological stations. Therefore, it often causes various misunderstandings and confusion in use.

In order to change this situation, the meteorological department adopted the method of naming typhoons. At the end of World War II, the United States identified four groups of girls' names with English letters (except Q, U, X, Y and Z) for the first time to name Atlantic hurricanes. Each group is arranged in alphabetical order. Such as the first group: Anna, B 1anche (Blanche), Camille. Te (Camil.te), etc. Until wcnda (wenda); Group 2: A 1nla (alma), BECL (J/ (Becky), Sierra (Celia), etc. Until Willner; The third and fourth groups are also named according to A to W. When the plane detects a typhoon, it will be named according to the order in which it appears. The first one will be named Anna, and the second one will be named B 1Anche, etc. When the first group of names is used up, use the names headed by the second group A again. The first typhoon name in the second year is followed by the last typhoon name in the previous year, which can be recycled. It is impossible for a typhoon to occur in any area in a year to exceed the sum of these four groups of names. Take the Pacific Northwest, which has the most typhoons in the world, for example, there are no more than 50 typhoons a year. Therefore, in the same year, it is impossible for each region to have the same name. Of course, the names of typhoons will be repeated in different years. Therefore, in front of the typhoon name. Be sure to indicate the year to show the difference.

Starting from 1959, China began to adopt the intensity and method of typhoon numbering. All typhoons formed or invaded in the Pacific Ocean and South China Sea to the west of east longitude 150 degrees and north of the equator are numbered according to the order of occurrence. For example, the first typhoon number of 1999 is 990 1, the second typhoon number is 9902, and so on.

This typhoon numbering method has been adopted by meteorological stations in many countries and regions. Some countries have long been accustomed to using the English names of typhoons, except the numbers. At the same time, it also indicates the English name of the typhoon.

C. classification of typhoons

In meteorology, tropical cyclones are classified according to their intensity. The United Nations World Meteorological Organization has formulated an internationally unified classification standard for tropical cyclones:

A tropical cyclone with a central maximum wind force of 7 (< 17. 1 m/s =) is called a tropical depression;

The maximum wind force in the center reaches 8-9 (17.2-24.4m/s), which is called a tropical storm.

A tropical cyclone with a central maximum wind force of10-1(24.5-32.6 m/s) is called a typhoon or hurricane.

D. the source of the typhoon

There are 80- 100 typhoons in the world every year (tropical cyclones in other areas are also called typhoons here), most of which occur in the Pacific Ocean and the Atlantic Ocean. According to statistics, typhoons in the western Pacific are mainly concentrated in four areas:

A. East of the Philippine Islands, near the Ryukyu Islands, this area is the area with the most typhoons in the northwest Pacific Ocean, and typhoons occur almost all year round. June-June mainly occurs in the waters near Samar Island in the Philippines and Mindanao to the south of 15 degrees north latitude. After June, the occurrence area expanded northward, appearing in the waters near Luzon Island to Ryukyu Islands in the Philippines from July to August, moving southward to the waters near Luzon Island in September, and moving to the waters south of 10 to February in the Philippines.

B. Near the Mariana Islands east of Guam. From July to June, 65438+ 10, there were typhoons around the island, and there were few typhoons before May. June and June,11-65438+February, mainly occurred in the waters near the south of the islands.

C. Sea area near Marshall Islands (typhoons are mostly concentrated in the northwest and north of the islands). Typhoon occurred most frequently in June of 10, and rarely in June of 1 0.

D. the sea surface in the north-central South China Sea. There are the most typhoon opportunities in June-September, with fewer typhoons in June-April, increasing gradually in May and decreasing in February, but most of them occur in the North Sea south of north latitude 15 degrees.

E. how did the typhoon form?

There are often many weak tropical eddies on the surface of tropical oceans, which we call "embryos" of typhoons, because typhoons always develop from such weak tropical eddies. Through meteorological satellites, it is found that only about 10% of a large number of tropical eddies on the ocean surface can develop into typhoons. How is a typhoon formed?

Generally speaking, the occurrence of typhoons requires the following basic conditions:

A. First of all, there must be a wide enough tropical ocean surface, which requires not only that the surface temperature of seawater is higher than 26.5℃, but also that the water temperature in a layer of seawater 60 meters deep should exceed this value. Among them, the vast ocean surface is the necessary natural environment for the formation of typhoons, because the friction between air molecules in typhoons consumes an average of 365,438+000-4,000 calories/cm **2 of energy every day, and this huge energy can only be supplied by the latent heat released by the vast tropical ocean. In addition, the strong wind around the tropical cyclone will make the sea water churn around the center, even in the typhoon center where the air pressure drops very low, and then spread around, so the sea water will churn around from the typhoon center. In a typhoon, this sea churning phenomenon can affect the depth of 60 meters. On the ocean surface where the seawater temperature is lower than 26.5℃, it is difficult to maintain a typhoon due to insufficient heat energy. In order to ensure that the sea surface temperature is always above 26.5℃ during this tumbling process, this warm water layer must have a thickness of about 60 meters.

B. Before the typhoon forms, there must be a weak tropical vortex in advance. We know that the operation of any machine consumes energy, which requires energy. Typhoon is also a "heat engine". It rotates there at such a huge scale and speed and consumes a lot of energy, so it needs an energy source. The typhoon's energy comes from the water vapor in the tropical ocean. In a pre-existing tropical vortex, the air pressure in the vortex is lower than that around it, and the air around it carries a lot of water vapor to the center of the vortex, causing upward movement in the vortex area; Wet air rises and water vapor condenses, releasing huge latent heat of condensation, which can make typhoons run. Therefore, even if there is a tropical ocean surface with high temperature and high humidity to supply water vapor, it is impossible to form a typhoon without the strong rise of air and the condensation and release of latent heat. Therefore, the upward movement of air is an important factor to produce and maintain typhoons. But the necessary condition is that a weak tropical vortex exists first.

C. there should be enough earth rotation deflection force. Because the geostrophic deflection at the equator is zero and gradually increases to the poles, the typhoon is located about 5 latitudes away from the equator. Due to the rotation of the earth, a force that changes the direction of air flow is generated, which is called "Earth rotation bias force". On the rotating earth, the rotation of the earth makes it difficult for the surrounding air to flow directly into the low pressure, but rotates counterclockwise along the center of the low pressure (in the northern hemisphere).

D above weak low pressure, the difference between high and low air direction and wind speed is small. In this case, the upper and lower air columns work together, and the high-altitude heat is easy to accumulate, thus heating up. Once the cyclone is generated, the ambient airflow above the friction layer will flow along the isobar, and the warming effect of the upper layer can be further completed. In the area north of 20 N, the climatic conditions have changed, mainly because the high-rise wind is very strong, which is not conducive to warming, and typhoons are not easy to appear.

As shown in the figure below.

These are just the necessary conditions for a typhoon. Having these conditions does not mean that there will be a typhoon. The occurrence of typhoon is a complicated process, which has not been fully understood so far.

In the next section, we will introduce the typhoon structure, related weather, typhoon path, typhoon forecast and typhoon prevention measures in detail.

F. The harm and utilization of typhoons

When a typhoon moves on the sea, it will set off huge waves, followed by violent storms, which will pose a serious threat to sailing ships. When a typhoon lands, the storm will cause great losses to people's lives and property, especially to agriculture and buildings.

However, typhoons do not always bring misfortune to mankind, except for its "evil" side, and sometimes they also benefit mankind. For some areas, if there is no typhoon, the growth of crops and the bumper harvest of agriculture in these areas are unimaginable. Typhoons in the northwest Pacific, hurricanes in the West Indies and tropical storms in the Indian Ocean account for almost 60% of the total number of strong tropical cyclones in the world, bringing abundant rain to fertile land and creating a suitable climate. Typhoon precipitation is the main source of summer precipitation in Jiangnan area and northeast provinces of China. It was the typhoon that lifted the drought in the Pearl River Delta, the two lakes basin and the Northeast Plain, and ensured a bumper agricultural harvest. It is precisely because of the large amount of precipitation brought by typhoon that many large and small reservoirs are full of rainwater, so that the hydroelectric generating set can operate normally and save raw coal 1 10,000 tons; On a hot day, a typhoon comes, and a cool breeze blows gently, which can also cool off the heat. Therefore, it is not unreasonable for some people to think that the typhoon "caused local disasters and benefited a large area".

Sources and paths of dust

In the past four spring years, there were 53 sandstorms in China (65438+9 in 0999, 0/4 in 2000, 0/8 in 2006 and 0/2 in 2002), among which 33 sandstorms originated in Gobi area in south-central Mongolia. This is the research result released by Li Huang, deputy director of China Meteorological Bureau, to the media on July 2nd. He said that in the spring of 2002, there were 12 sandstorms in northern China. It has three characteristics: concentrated occurrence period, strong occurrence intensity and wide influence range. The sources of dust weather affecting China can be divided into two types: overseas and domestic. The analysis shows that two-thirds of the dusty weather originated in southern Mongolia and was supplemented by dusty materials when passing through northern China. The sand source in China is only about one third. The dusty weather in Central Asia (Kazakhstan) is unlikely to affect the eastern part of Northwest China or even North China. The Taklimakan Desert in southern Xinjiang is a high incidence area of sandstorm weather in China, but it generally does not affect the eastern part of northwest China and North China. The path of sandstorm weather in China can be divided into northwest path, west path and north path: northwest path 1. Sandstorm weather generally originates in the central and western plateau of Mongolia or Alashan Plateau in western Inner Mongolia, and mainly affects northwest and north China. Northwest Route 2. Dust weather originated in southern Mongolia or central and western Inner Mongolia, mainly affecting the eastern part of northwest China, northern North China and most of northeast China; To the west, dusty weather originated in Gobi area in southwest or south Mongolia and desert area in western Inner Mongolia, mainly affecting northwest and north China. In the northerly route, dusty weather generally originates in the vast area south of Ulaanbaatar, Mongolia, and mainly affects the eastern part of northwest China, most of north China and southeast China.

Dust weather in China in recent years

According to statistics, there were eight sandstorms in China in 1960s, three in 1970s 14 in 1980s14, and more than 20 in 1990s, and the scope of sandstorms became wider and wider with heavy losses. The situation of several major gale and sandstorm weather in China since the 1990s is introduced as follows:1993: From April to early May, gale weather appeared many times in the north. From April 19 to May 8, Gansu, Ningxia and Inner Mongolia were successively hit by strong winds and sandstorms. On May 5-6, eastern Xinjiang, Hexi in Gansu, most of Ningxia and western Inner Mongolia were hit by severe sandstorms, causing serious losses. 1994: From April 6, strong winds blew from Mongolia and western Inner Mongolia, and the dust in the Gobi desert in the north was lifted by the wind and floated over the Hexi Corridor, and the loess lasted for several days. 1 995:165438+1On 7 October, more than 40 counties (cities) in Shandong were hit by heavy rain, with 35 people killed, 12 1 missing, 320 injured and direct economic losses/kloc-0. 1996: On May 29th and 30th, 1965, the worst sandstorm swept the west of Hexi Corridor. The black wind suddenly broke out, the world was closed, the dust filled, the trees collapsed, and people had difficulty breathing. The direct economic loss in Jiuquan area, which suffered the most, reached more than 200 million yuan. 1998: On April 5, the central and western Inner Mongolia, southwestern Ningxia and Hexi Corridor in Gansu were hit by strong sandstorms, which affected a wide range, including Beijing, Jinan, Nanjing and Hangzhou. On April 19, Tutanto 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. 19 In the early morning of May 1, northern Xinjiang was suddenly hit by strong winds. The wind power in the tuyere areas such as Alashankou and Tacheng reaches 9 to 10, and the instantaneous wind speed reaches 32 meters per second. The winds in other areas generally reach 6 to 7. Strong winds blew down trees and cut off power lines in some areas. 1999: From April 3rd to 4th, there were continuous strong winds and sandstorms in Hohhot for two consecutive days. Sandstorms range from the west of Inner Mongolia Autonomous Region to the south of Tongliao City in the east, with instantaneous wind speed 16 meters per second. Maximum wind force in Dalat Banner of Yikezhao League 10. 2000: On March 22-23, there was a large-scale dusty weather in Inner Mongolia Autonomous Region, and some dust 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, causing pedestrian injuries and vehicle damage. 2002: From March 18 to March/2 1 day, a sandstorm weather process with the largest scope, strongest intensity, the most serious impact and the longest duration since the 1990s, attacked China North1400,000 square kilometers and affected the population1300,000.

Concept, regulations and standards of sandstorm

First, the concept of dusty weather:

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 turbid and the horizontal visibility less than 500 meters.

Second, the classification of dust weather 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 and at the same observation time, floating dust weather occurred in five or more countries in China's 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's weather forecast area;

Sandstorm weather process: in the same weather process, sandstorms occurred in three or more countries in China's weather forecast area at the same observation time;

Strong sandstorm weather process: In the same weather process, more than three countries in China's weather forecast area basically (quasi) stand at the same observation time and have strong sandstorms.

Three, sand and dust weather forecast and early warning standards:

1, decision service

When there is expected to be a sandstorm weather process in the next 24 hours, the sandstorm weather forecast will be released in internal bulletins, special reports and decision-making service materials.

2. Public forecast

National standards:

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, a sandstorm warning will be issued 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 meteorological bureaus of provinces (autonomous regions and municipalities) with reference to national standards.

Description:

1, the provincial sandstorm weather forecast and early warning release standard was 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.

Causes and physical mechanism of sandstorm weather

Causes of sandstorm 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 of sandstorm formation

Under the favorable conditions of 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-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 failure modes 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. 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.

The harm of black wind

The harm of black wind mainly has two words, one is wind and the other is sand.

Strong winds have two other hazards: one is wind damage, and the other is scraping the ground.

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,1May 5, 1993, black wind in northwest China knocked out 85,000 stamens of fruit trees, and shelter forests and timber forests were broken or uprooted 109400. 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. Such as1where sand burial occurred in the black wind on May 5, 993, the average thickness of sand burial was 20 cm, and the thickest part reached1.2 m.

More importantly, the loss of human 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.

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, etc., pollute the natural environment, destroy crop growth, and cause 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:

1, ecological environment deterioration

When sandstorms occur, dust and floating dust carried by strong winds are everywhere, and the number of people passing through areas with air turbidity, choking nose and eyes, respiratory tract 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 property

1On May 5, 1993, 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 people died and 0/53 people were seriously injured. 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 (plane, car and other traffic accidents)

Sandstorm weather often affects traffic safety, causing planes to fail to take off or land normally, and making cars and train carriages rupture, stop or derail.

Sandstorms originate from soil wind erosion.

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, Chinese Academy of Sciences, recently successfully completed a sandstorm wind tunnel simulation experiment specially designed to explore the mechanism of sandstorm initiation 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.

This experiment also proves that plant measures are one of the effective methods to prevent and control sandstorms. Experts believe that plants usually affect wind erosion in three forms: dispersing certain wind momentum on the ground to reduce the transmission between airflow and dust; Stop the movement of soil, dust, etc.

In addition, through experiments, the researchers concluded that the occurrence of sandstorms is not only the product of specific natural environmental conditions, but also has a corresponding relationship with human activities. Man-made overgrazing, deforestation, industrial and mining traffic construction, especially man-made overgrazing, destroyed the ground vegetation, disturbed the ground structure, formed a large area of sandy land, and directly accelerated the formation and development of sandstorms.

Control and preventive measures of sandstorm

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.

Four lines of defense to stop sandstorms

First, establish an ecological barrier mainly based on afforestation in the surrounding areas of Beijing and Tianjin in the north of Beijing;

The second is to build an ecological restoration and protection belt with returning farmland to forests as the core in the central and western parts of Hunshandake, Inner Mongolia;

Thirdly, the Ordos ecological barrier centered on the Yellow River irrigation area and Mu Us sandy land should be built in Hetao and Huangsha areas.

Fourth, establish a long-term cooperation plan framework with Mongolia to prevent and control sandstorms as soon as possible and set up a protective barrier for Mongolia.

The role of sandstorm in ecosystem

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. The neutralization of sand dust and its soil particles increased the PH value of precipitation in northern China, Korea and Japan by 0.8-2.5, 0.5-0.8 and 0.2-0.5 respectively. If there is no dust, 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.