A. What is a typhoon?
Typhoons are violent storms that occur in the tropical oceans in the northwest Pacific and South China Sea. You must have seen vortices appearing in rivers from time to time. In fact, typhoons are air vortices that rapidly rotate around their center in the atmosphere and move forward at the same time. It rotates counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. In meteorology, vortices in the atmosphere are called cyclones. Because vortices in the atmosphere such as typhoons occur in the tropical ocean, they are called tropical cyclones.
Why is it called a typhoon? Some people say that in the past, people did not understand that typhoons originate from the Pacific Ocean. They thought that this huge storm came from Taiwan, so it was called a typhoon. Others believe that typhoons hit Guangdong Province the most, Typhoon evolved from the Cantonese word for "big wind".
In fact, almost all countries and regions on the west coast of the ocean in the world are affected by tropical ocean cyclones, but people in different regions give them different names.
Those in the northwest Pacific and South China Sea are called typhoons, those in the Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and the Eastern Pacific are called hurricanes, those in the Indian Ocean and Bay of Bengal are called tropical storms, and those in Australia are called tropical cyclones .
B. Naming and numbering of typhoons
The naming, definition, classification methods and determination of the center position of tropical cyclones are different in different countries and methods, even if they are the same A country is not exactly the same between different weather stations. Therefore, various misunderstandings often occur, resulting in 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 first determined four groups of girl names starting with English letters (except Q, U, X, Y, and Z) to name Atlantic hurricanes. Each group is ordered alphabetically. Such as the first group: Anna (Anna), B1anche (Blanche), Camil. te (Camille), etc., until wcnda (Wenda); second group: A1nla (Alma), Becl (J/(Becky)), Cella (Celia), etc., until wilna (Wilna); third group: Group, the fourth group is also named according to A to W. When the aircraft detects the typhoon, it will be named according to the order of occurrence. The first one will be named Anna, the second one will be named B1anche... etc. When the group name is used up, the first name headed by group A is used. The first typhoon name of the second year is used after the last typhoon name of the previous year, and the cycle continues throughout the year. The total number of typhoons in any one region cannot exceed the total number of these four groups of names. In the northwest Pacific, where the most typhoons occur in the world, there are no more than 50 in a year, so in the same year, there are no more than 50 in each region. There may be duplicate names. Of course, the names of typhoons will appear repeatedly in different years. Therefore, the year must be indicated in front of the typhoon name to show the difference.
my country started in 1959. The method of numbering typhoons is adopted. Any typhoons that form or invade the Pacific and South China Sea areas west of 150 degrees east longitude and north of the equator will be numbered in sequence according to the order of their occurrence. For example, those that occurred in 1999. The first typhoon is coded as 9901, the second typhoon is coded as 9902... and so on.
This method of numbering typhoons has been adopted by meteorological observatories in many countries and regions. . Some countries take into account the long-standing international practice of using English names for typhoons and also indicate the English name of the typhoon.
C. Typhoon classification
In meteorology, tropical cyclones are classified differently according to their intensity. The United Nations World Meteorological Organization once developed an internationally unified classification standard for tropical cyclones:
The maximum wind force in the center is level 7 (<17.1 meters/meter). A tropical cyclone with seconds = is called a tropical depression;
A tropical cyclone with a maximum central wind speed of level 8-9 (17.2-24.4 meters/second) is called a tropical storm;
A tropical storm with a maximum central wind speed of 10 A tropical cyclone of Category -11 (24.5-32.6 meters/second) is called a typhoon or hurricane.
D. The origin of typhoons
There are an average of 80-100 typhoons in the world every year (we also refer to tropical cyclones in other areas as typhoons), most of which Occurs in the Pacific and Atlantic Oceans. Statistics show that the occurrence of typhoons in the Western Pacific is mainly concentrated in four areas:
a. East of the Philippine Islands and the sea near the Ryukyu Islands. This area is the area where the most typhoons occur in the northwest Pacific, almost all year round. There is a typhoon. From l to June, it mainly occurs in the sea near Samar Island in the Philippines and east of Mindanao Island south of 15 degrees north latitude. After June, this occurrence area extends to the north, and appears from Luzon Island in the Philippines to the Ryukyu Islands from July to August. In September, it moved southward to the sea near the east of Luzon Island, and from October to December it moved south to the sea south of 15 degrees north latitude east of the Philippines.
b. Near the Mariana Islands east of Guam. Typhoons are generated in the sea around the archipelago from July to October. Typhoons are rare before May. Typhoons mainly occur in the sea near the south of the archipelago in June and November-December.
c. On the sea near the Marshall Islands (typhoons are mostly concentrated in the northwest and north of the islands). Typhoons occur most frequently here in October, and rarely occur from January to June.
d. The central and northern parts of the South my country Sea. Typhoons are most likely to occur here from June to September, and rarely from January to April. They gradually increase in May and decrease again in October and December, but they mostly occur in the northern sea south of 15 degrees north latitude.
E. How typhoons are formed
There are often many weak tropical eddies on the tropical ocean surface. We call them "embryos" of typhoons, because typhoons are always caused by This weak tropical vortex develops and grows. It has been determined through weather satellites that only about 10% of the large number of tropical vortices that appear on the ocean can develop into typhoons. How does a typhoon form?
Generally speaking, for the occurrence of a typhoon, the following basic conditions need to be met:
a. First of all, there must be a sufficiently broad tropical ocean surface. This ocean surface not only requires the surface temperature of the seawater to be higher than 26.5°C, but also the water temperature in a layer of seawater 60 meters deep must exceed this value. Among them, the vast ocean is the necessary natural environment for the formation of typhoons. Because the friction between air molecules inside the typhoon consumes an average of 3100-4000 calories/cm**2 of energy every day. This huge energy can only be released by the vast tropical ocean. Only latent heat can be supplied. In addition, the strong winds rotating around the tropical cyclone will cause the sea water near the center to churn. In the center of the typhoon where the air pressure drops very low, it can even cause the ocean surface to surge upward, and then spread out, so the sea water moves from the center of the typhoon to the surrounding areas. tumbling. This churning phenomenon of sea water in typhoons can affect a depth of 60 meters. On the ocean surface where the seawater temperature is lower than 26.5°C, 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°C during this churning process, this warm water layer must be about 60 meters thick.
b. Before a typhoon forms, a weak tropical vortex must exist. We know that the operation of any machine consumes energy, which requires an energy source. A typhoon is also a "heat engine". It rotates at such a huge scale and speed and consumes a lot of energy, so it needs an energy source. The energy of typhoons comes from water vapor on tropical oceans. In a pre-existing tropical vortex, the air pressure in the vortex is lower than the surrounding air. The surrounding air carries a large amount of water vapor to the center of the vortex, and moves upward in the vortex area; the moist air rises and the water vapor condenses. Only by releasing huge latent heat of condensation can the big machine of typhoon operate. Therefore, even if there is a supply of water vapor from the tropical ocean with high temperature and humidity, it is impossible for a typhoon to form if there is no strong rise of air to cause condensation and release of latent heat. Therefore, the upward movement of air is an important factor in generating and maintaining typhoons. However, the necessary condition is the first existence of a weak tropical vortex.
c. There must be a large enough earth rotation deflection force. Because the geostrophic deflection force at the equator is zero and gradually increases toward the poles, the location of the typhoon is approximately 5 or more latitudes away from the equator. Due to the rotation of the earth, a force is generated that changes the direction of the air flow, which is called the "earth rotation deflection force".
On a rotating Earth, the effect of the Earth's rotation makes it difficult for the surrounding air to flow directly into the low pressure. Instead, it rotates counterclockwise along the center of the low pressure (in the Northern Hemisphere).
d. Above weak low pressure, the difference in wind direction and speed between high and low altitudes is smaller. In this case, the upper and lower air columns act in unison, and heat easily accumulates in the upper air, causing warming. Once a cyclone is generated, the ambient airflow above the friction layer will flow along the isobars, and the upper-level warming effect can be further completed. In the area north of 20°N, climate conditions have changed, mainly due to strong upper-level winds, which is not conducive to warming, and typhoons are less likely to occur.
As shown in the figure below.
The above mentioned are only the necessary conditions for the occurrence of typhoons. Meeting these conditions does not mean that a typhoon will occur. The occurrence of typhoons is a complex process that has not yet been fully understood.
We will introduce details about the structure of typhoons, related weather, the path of typhoons that hit my country, typhoon forecasts and typhoon prevention measures in the following sections.
F. The harm and use of typhoons
Typhoons moving on the sea will set off huge waves, and violent storms will follow, which can cause serious threats to sailing ships. When a typhoon makes landfall, violent storms will cause huge losses to people's lives and property, especially agriculture and buildings.
However, not all typhoons bring misfortune to mankind. In addition to their "evil" side, they also sometimes benefit mankind. For some areas, without typhoons, the growth of crops and agricultural harvests in these areas would be 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. They bring abundant rain to the fertile land and create a suitable climate. Typhoon precipitation is the main source of summer rainfall in the Jiangnan region and Northeastern provinces of my country. It is precisely the typhoon that relieves the drought in the Pearl River Delta, the Lianghu Basin and the Northeast Plains and ensures a bumper agricultural harvest. It is also because of the large amount of precipitation brought by the typhoon , so that many large and small reservoirs can be filled with rainwater, and hydropower generating units can operate normally, saving tens of thousands of tons of raw coal; on hot days, when typhoons come, cool breezes can also cool down the heat; therefore, some people think that typhoons are "causing local disasters" , benefiting a large area." This is not unreasonable.
Sources and paths of sand and dust
In the past four springs, there have been 53 earthquakes in my country (9 in 1999, 14 in 2000, 18 in 2001, and 2002). 12 times per year) of sand and dust weather, 33 of which originate from the Gobi region in central and southern Mongolia. In other words, about 60% of the sand and dust that ravages our country every year comes from abroad. This is the research result announced to the media by Li Huang, deputy director of the China Meteorological Administration, on July 2. He said that in the spring of 2002, 12 sand and dust weather processes occurred in northern my country. It has three characteristics: concentrated occurrence period, high intensity of occurrence, and wide range of influence. The sources of sand and dust weather affecting my country can be divided into two types: overseas and domestic. Analysis shows that: two-thirds of the sand and dust weather originates in the southern region of Mongolia, and is supplemented and strengthened by sand and dust materials when passing through northern my country; the sand source within the country is only about one-third. The sand and dust weather that occurs in Central Asia (Kazakhstan) is unlikely to affect the eastern part of northwest my country and even North China. The Taklimakan Desert in southern Xinjiang is an area with high incidence of sand and dust weather in my country, but it generally does not affect the eastern part of Northwest China and North China. my country's sand and dust weather paths can be divided into northwest paths, westward paths and northerly paths: Northwest 1 path, sand and dust weather generally originates from the central and western Mongolian Plateau or the Alxa Plateau in western Inner Mongolia, mainly affecting northwest my country and North China; In the northwest 2 path, the sand and dust weather originates 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; in the west path, the sand and dust weather originates in the Gobi area in southwest or southern Mongolia. The desert area in western Inner Mongolia mainly affects northwest my country and North China; in the northerly direction, sand and dust weather generally originates from the vast area south of Ulaanbaatar, Mongolia, mainly affecting the eastern part of the northwest region, most of North China, and the southern part of Northeast China.
Strong sand and dust storms in my country in recent years
According to statistics, severe sandstorms occurred 8 times in our country in the 1960s, 13 times in the 1970s, and 14 times in the 1980s. It has happened more than 20 times since the 1990s, and its scope has become wider and wider, causing more and more losses. The relevant situation of several major strong winds and sandstorms that have occurred in my country since the 1990s is introduced as follows: 1993: From April to early May, strong winds occurred many times in the north. From April 19 to May 8, Gansu, Ningxia, and Inner Mongolia were successively hit by strong winds and sandstorms. Among them, from May 5 to 6, a huge sandstorm hit eastern Xinjiang, Hexi of Gansu, most of Ningxia, and western Inner Mongolia, causing serious losses. 1994: Beginning on April 6, strong winds blew from Mongolia and western Inner Mongolia. The sand and dust from the Gobi desert in the north rose with the wind and floated over the Hexi Corridor, filling the sky with loess for several days. 1995: On November 7, more than 40 counties (cities) in Shandong were hit by a storm. 35 people died, 121 people were missing, 320 people were injured, and direct economic losses were more than 1 billion yuan. 1996: From May 29th to 30th, the most serious severe sandstorm since 1965 hit the western part of the Hexi Corridor. Black winds suddenly rose, the sky and the earth closed, sand and dust filled the air, trees collapsed, people had difficulty breathing, and the most destructive The severe direct economic losses in Jiuquan area amounted to more than 200 million yuan. 1998: On April 5, the central and western parts of Inner Mongolia, the southwestern part of Ningxia, and the Hexi Corridor of Gansu were hit by strong sandstorms, which affected a wide range of areas, including Beijing, Jinan, Nanjing, Hangzhou and other places. On April 19, the Tushantuo Basin in northern and eastern Xinjiang was hit by strong winds with an instantaneous wind force of magnitude 12, accompanied by sand and dust in some areas. This severe typhoon caused a large amount of property damage, with 6 people dead, 44 missing, and 256 injured. In the early morning of May 19, northern Xinjiang was suddenly hit by strong winds. The wind force in Alashankou, Tacheng and other wind outlet areas reached level 9 to 10, and the instantaneous wind speed reached 32 meters per second. The wind force in other areas generally reached level 6 to 7. Strong winds knocked down trees and cut power lines in some areas. 1999: From April 3 to 4, sustained strong winds and sandstorms occurred in Hohhot for two consecutive days. The sandstorm ranged from the western part of the 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 highest wind force in Dalat Banner of Yikezhao League reached level 10. 2000: From March 22 to 23, a large-scale sandstorm occurred in the Inner Mongolia Autonomous Region. Some of the sand was carried over Beijing by strong winds, aggravating the level of sand blowing. On March 27, a sandstorm hit Beijing again, with instantaneous winds reaching level 8 to 9 in some areas. Seven workers who were working on the roof of a two-story building in Anxiangli Community were blown off by strong winds, and two died on the spot. Some billboards were knocked down by strong winds, injuring pedestrians and damaging vehicles. 2002: From March 18 to 21, the sand and dust weather process with the largest scope, strongest intensity, most severe impact, and longest duration since the 1990s hit more than 1.4 million square kilometers of land in northern my country, affecting the population. Reaching 130 million.
Concepts, regulations and standards of sandstorms
1. Concept of sandstorms:
Sandstorms are divided into four categories: floating dust, blowing sand, sandstorms and strong sandstorms .
Floating dust: Dust and fine sand float evenly in the air, making the horizontal visibility less than 10 kilometers;
Blowing sand: The wind blows up the dust and sand on the ground, making the air thicker. Turbidity, a weather phenomenon with horizontal visibility within 1 km to 10 km;
Sandstorm: Strong winds blow up a large amount of dust and sand on the ground, making the air very turbid, and a weather phenomenon with horizontal visibility less than 1 km;
Strong 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 less than 500 meters.
2. Classification of sand and dust weather processes
Sand and dust weather processes are divided into four categories: floating dust weather processes, blowing sand weather processes, sand and dust storm weather processes and strong sand and dust storm weather processes.
Dust weather process: During the same weather process, 5 or more national basic (accurate) stations in my country’s weather forecast area experienced floating dust weather at the same observation time;
Sand-blowing weather process: During the same weather process, 5 or more national basic (accurate) stations in my country's weather forecast area experienced sand-blowing weather at the same observation time;
Sand storm Weather process: During the same weather process, sandstorms occurred at the same observation time at three or more countries' basic (accurate) stations in my country's weather forecast area;
Strong sandstorm weather process: During the same weather process, strong sandstorms occurred at the same observation time at three or more national basic (accurate) stations in my country's weather forecast area.
3. Sand and dust weather forecast warning issuance standards:
1. Decision-making service
When sand and dust weather processes are expected to occur in the next 24 hours, in Sand and dust weather forecasts are published in internal bulletins, special reports and decision-making service materials.
2. Public forecast
National standard:
It is expected that sand and dust weather will occur in the next 24 hours, and the impact will be large or affect In the Beijing-Tianjin area, a sandstorm warning was issued to the public. ;
When a sandstorm or strong sandstorm weather process is expected to occur in the next 24 hours and will cause serious impacts, a sandstorm warning will be issued to the public.
Provincial standards:
Determined by the provincial (autonomous and municipal) meteorological bureaus with reference to national standards.
Notes:
1. Provincial sand and dust weather forecast warning issuance standards shall be reported to the China Meteorological Administration for filing.
2. Sand and dust weather forecasts and warnings should include the area, period, intensity, possible impacts and countermeasures of sand and dust weather.
3. Before issuing sand and dust weather forecast warnings to the public, the Central Meteorological Observatory should promptly and effectively notify the relevant provincial meteorological observatories. Before issuing sand and dust weather forecast warnings to the public, provincial meteorological observatories should promptly and effectively notify the central Reports from the Meteorological Observatory and related meteorological stations.
Causes and physical mechanisms of sand and dust storms
Causes of sand and dust storms
Weather conditions that are conducive to strong winds or strong winds, favorable sand and dust source distribution and favorable Unstable air conditions are the main reason for the formation of sandstorms or severe sandstorms. Strong wind is the driving force for sandstorms, and sand and dust sources are the material basis of sandstorms. Unstable thermal conditions are conducive to the increase in wind power and the development of strong convection, thereby entraining more sand and dust and carrying it higher.
In addition, drought and lack of rain in the early stage, warm weather, and rising temperatures are the special weather and climate background for the formation of sandstorms; the development of convective cells in front of the ground cold front into clouds or squall lines is conducive to sandstorms The development and strengthening of small and medium-scale systems; the terrain conditions that are conducive to increased wind speed, that is, the narrow tube effect, are one of the favorable conditions for the formation of sandstorms.
The physical mechanism of the formation of sand and dust storms
Under the conditions of extremely favorable large-scale environment, high-altitude dry cold jet stream, strong vertical wind speed, wind shear and thermally unstable stratification, frontal areas are caused The formation and development of nearby medium- and small-scale systems intensifies the pressure and temperature gradients before and after the frontal zone, forming a huge pressure-temperature gradient before and after the frontal zone. Under the simultaneous action of momentum downward transmission and gradient deviation wind, the near-surface wind speed rises sharply, kicking up surface sand and dust, forming sandstorms or strong sandstorms.
The main hazards of sandstorms
⑴ Strong winds: Strong winds carrying fine sand and dust destroy buildings and public facilities, causing death.
⑵ Sand burial: Farmland, channels, cottages, railways, pastures, etc. are buried by a large amount of sand due to wind and sand flow, 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 to varying degrees, and the depth of wind erosion can reach 1 to 10 centimeters. It is estimated that my country's annual loss of fine soil matter caused by sandstorms is as high as 106 to 107 tons, most of which have particle sizes below 10 microns, causing serious damage to the land productivity of farmland and pastures in the source areas.
⑷ Atmospheric pollution: In the source areas and affected areas of sandstorms, respirable particulate matter (TSP) in the atmosphere increases, and air pollution intensifies. Taking the "5.5" extremely severe sandstorm in 1993 as an example, the TSP concentration of outdoor air in Jinchang City, Gansu Province reached 1016 mg/m3 and indoors was 80 mg/m3, exceeding the national standard by 40 times. From March to April 2000, the Beijing area was affected by sandstorms. The air pollution index reached level 4 or above for 10 days, which also affected many cities in eastern my country. From March 24 to 30, the daily pollution index in 18 cities, including Nanjing and Hangzhou, exceeded level 4.
The harm of black wind
The harm of black wind mainly has two words, one is wind and the other is sand.
There are two dangers of strong wind: one is wind damage, and the other is land erosion.
Let’s talk about wind damage first. Strong winds damaged buildings, knocked down or uprooted trees and poles, and tore off farmers' plastic greenhouses and farmland mulch films, etc. In addition, April and May in the northwest region are the time when economic crops such as fruits, vegetables, sugar beets, and cotton emerge, grow cotyledons or true leaves, and fruit trees bloom. At this time, they are least resistant to wind and sand. At least, the leaves are covered with dust, which weakens photosynthesis, affects respiration, and reduces crop yield; at worst, the seedlings die and the flowers fall, let alone mature fruits. For example, the black wind on May 5, 1993 knocked down the stamens of 85,000 fruit trees in the northwest region, and broke or uprooted 109,400 shelterbelts and timber forests. In addition, strong winds knocked down power poles, causing water and power outages, affecting industrial and agricultural production. The power and water outage caused by the black wind on May 5, 1993 caused economic losses of 83 million yuan to Jinchuan Company in Jinchang City alone.
When strong winds act on loose soil in arid areas, they will remove a layer of topsoil, which is called wind erosion. For example, the average wind erosion depth of the black wind on May 5, 1993 was ten centimeters (up to 50 centimeters), which means that an average of 60 to 70 cubic meters of fertile topsoil per acre 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 accumulate the sand brought by it in the soil, greatly reducing the soil fertility. In addition, strong winds and sand particles can also wear away a layer of the surface of buildings and crops, which is called abrasion, which is also a disaster.
The main harm caused by sand is sand burial. As mentioned before, in terrains such as narrow tubes, windward and ridges, due to high wind speeds, the main damage caused by wind and sand is wind erosion, while in terrains with low wind speeds such as leeward depressions, the main damage caused by wind and sand is sand burial. For example, where sand burial occurred during the black wind on May 5, 1993, the sand burial thickness averaged 20 centimeters, with the thickest point reaching 1.2 meters.
More importantly, the loss of human life. For example, in the black storm on May 5, 1993, 85 people were killed, 264 were injured, and 31 were missing. In addition, 120,000 large livestock died or were lost, 5.6 million acres of crops were damaged, more than 2,000 kilometers of water channels, the lifeline of sand-buried arid areas, were lost, and the Lanzhou-Xinjiang Railway was suspended for 31 hours. The total economic loss exceeded 540 million yuan.
Hazards of sandstorms
Sandstorms are highly disastrous weather that occurs in northwest my country and northern parts of North China. They can cause house collapse, traffic and power supply obstruction or interruption, fires, and human storage. casualties, etc., polluting the natural environment, destroying crop growth, causing serious losses and great harm to the national economic construction and the safety of people's lives and property. The main hazards of sandstorms are in the following aspects:
1. Deterioration of the ecological environment
When sandstorms occur, the sand, stones and floating dust wrapped in strong winds spread everywhere, making the air in any area passing through turbid and choking. The number of eye, respiratory and other diseases has increased. For example, during the severe sandstorm that occurred in Jinchang City on May 5, 1993, the measured dust content in the outdoor air was 1016 mm/cubic centimeter, and the indoor dust content was 80 mm/cubic centimeter, exceeding the national dust content in living areas. 40 times the standard.
2. Impact on production and life
Sandstorm weather carries a large amount of dust that blocks the sun and light, and the weather is gloomy, resulting in reduced solar radiation and poor visibility for several hours to more than ten hours. It is easy to make people feel depressed and reduce the efficiency of work and study. In mild cases, a large number of livestock can be infected with respiratory and gastrointestinal diseases. In severe cases, it can lead to the death of a large number of "spring fatigue" livestock and scrape away fertile farmland, seeds and seedlings.
Sandstorms will also intensify wind erosion and desertification of surface soil, covering plant leaves with thick dust, affecting normal photosynthesis and causing crop yield reductions.
3. Loss of life and property
On May 5, 1993, a severe sandstorm occurred in Jinchang, Weiwu, Minqin, Baiyin and other cities in Gansu Province, affecting 2.5355 million farmland acres, 42,800 trees were lost, causing direct economic losses of 236 million yuan, 50 deaths, and 153 serious injuries. On April 12, 2000, severe sandstorms occurred in Yongchang, Jinchang, Weiwu, Minqin and other cities. According to incomplete statistics, only Jinchang and Weiwu suffered direct economic losses of 15.34 million yuan.
4. Traffic safety (traffic accidents such as airplanes and cars)
Sandstorms often affect traffic safety, causing planes to be unable to take off or land normally, causing damage to the glass of cars and train carriages, and causing parking problems. Luck or derailment.
Sandstorms cause soil wind erosion
According to Xinhua News Agency, Lanzhou, with the efforts of experts from the Cold and Arid Regions Environment and Engineering Institute of the Chinese Academy of Sciences, a project was launched to explore the origin of sand and dust materials. The sandstorm wind tunnel simulation experiment specially established for the transmission mechanism was successfully completed recently.
Through experiments, experts have discovered 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 air flow, wind speed, and related conditions of wind force during soil wind erosion are the most important factors. In addition, soil moisture content is also one of the important reasons affecting soil wind erosion.
This experiment also proved that plant measures are one of the effective methods to prevent sandstorms. Experts believe that plants usually affect wind erosion in three ways: dispersing a certain amount of wind momentum on the ground and reducing the transfer between airflow and dust; and preventing the movement of soil, dust, etc.
In addition, through experiments, researchers have drawn a conclusion: the occurrence of sandstorms is not only a product of specific natural environmental conditions, but also has a corresponding relationship with human activities. Man-made overgrazing, deforestation of forest vegetation, industrial and mining transportation construction, and especially man-made excessive reclamation destroy ground vegetation, disturb the ground structure, and form large areas of desertified land, which directly accelerate the formation and development of sandstorms.
Sandstorm management and preventive measures
1. Strengthen environmental protection and elevate environmental protection to the level of the legal system.
2. Restore vegetation and strengthen the biological protection system to prevent sandstorms. Protect and restore forest and grass vegetation in accordance with the law, prevent the further expansion of land desertification, and reduce the sources of sand and dust as much as possible.
3. Formulate disaster prevention, disaster resistance, and disaster relief plans based on local conditions in different regions, actively promote various disaster reduction technologies, and build a number of demonstration projects to gradually promote them on a point-by-point basis to further improve the regional comprehensive defense system.
4. People’s long-term predatory development of natural resources has caused serious damage to the natural ecological environment, and the deterioration of the environment has provided a rich source of sand and dust materials for sandstorms.
5. Control population growth, reduce the pressure of human factors on land, and protect the environment.
6. Strengthen popular science propaganda on the relationship between the occurrence and harm of sandstorms and human activities, so that people will realize that once the environment they live in is destroyed, it will be difficult to recover. This will not only aggravate natural disasters such as sandstorms, but also cause A vicious circle, so people must consciously protect their living environment.
Four lines of defense to prevent sandstorms
First, establish an ecological barrier focusing on afforestation in the areas surrounding Beijing and Tianjin in northern Beijing;
Second, In the central and western Hunshandake region of Inner Mongolia, an ecological restoration protection zone centered on returning farmland to forest has been established;
Third, an ecological restoration protection zone centered on the yellow irrigation belt and Mu Us sandy land has been established in the Hetao and Huangsha areas. Ordos ecological barrier in the center;
Fourth, establish a long-term cooperation plan framework with Mongolia to prevent sandstorms as soon as possible and set up a protective barrier to Mongolia.
The role of sandstorms in the ecosystem
Although sandstorms cause many hazards, the entire sandstorm process is also an indispensable part of the natural ecosystem, such as Australia's red The large amount of iron carried in sandstorms has proven to be an important source of nutrients for phytoplankton in the Antarctic Sea, and phytoplankton can consume large amounts of carbon dioxide to slow down the harm of the greenhouse effect. Therefore, the impact of sandstorms is not entirely negative.
Perhaps on another level, sandstorms may also be a symptom of the earth's response to environmental changes, just like we cough when we have a cold to eliminate waste from the trachea. Australia has brought together many climate scientists to study how sandstorms provide nutrients to the Tasman Sea and many other effects. They found that red quartz deposits from Australian sandstorms can also be found in New Zealand, and in turn fertilize New Zealand's land; therefore, the nutrient losses caused by Australian sandstorms can lead to nutrient gains in New Zealand's land. For example, analysis of fertile soil sediments in Hawaii can also prove that many nutrients come from the distant interior of Eurasia. Because the two places are thousands of miles apart, ordinary wind cannot blow inland dust to such a far place. Therefore, it is sandstorms that carry fine but nutrient-containing dust up to an altitude of 3,000 meters, across the ocean, and then scatter them like seeds. Come down. In addition to the Hawaiian Islands, scientists have also discovered that the rainforest in the Amazon Basin, the largest green lung on earth, also benefits from sandstorms. An important source of nutrients for it is also dust in the air. The secret behind how sandstorms can turn rocks into lush greenery is that dust aerosols contain iron ions and other ingredients that help plant growth. In addition, since sandstorms are often born in dry and highly saline land, some soil particles carried by sandstorms often contain alkaline substances, which can often slow down acid rain or soil acidification in settlement areas near sandstorms. Mr. Wang Zifa from the Institute of Atmospheric Physics of the Chinese Academy of Sciences once said: "Sandstorms indeed reduce the acidity of acid rain. The neutralization of dust and soil particles increases the PH value of precipitation in northern China by 0.8-2.5 and in South Korea by 05.-0.8 , Japan increased by 0.2-0.5. Without the effect of sand and dust, the harm of acid rain in many northern areas would be much more serious. "Therefore, although sand and dust storms are very harmful, they are also a necessary process in the natural ecology of the earth. Sandstorms have occurred throughout human history. It’s just that we should be more active in looking for the mechanism of abnormal sandstorm frequency to truly solve the environmental hazards of abnormal climate change.