The north encountered the strongest sand and dust this year, meteorological experts interpreted -
Why is Beijing now a "blue sun"? How long will it take for the "mud rain" in Changchun?
Affected by cold air, many places in northern China have encountered the strongest sand and dust weather this year. From March 3 to the morning of March 21, sand or floating dust weather has occurred in many places in the north, including sandstorms in central and eastern Inner Mongolia, northwestern Hebei, Beijing and other places, and the local PM22 exceeded 10 micrograms / cubic meter, and the visibility was significantly reduced.
On March 3, the air in Beijing, Baoding, Inner Mongolia and other places has reached serious pollution, and the air quality pollution index once exceeded 22. Under the influence of sand and dust, a rare "blue sun" appeared in the sky of Beijing on the 500nd; In addition, Jilin Changchun also ushered in a "mud rain" process on the 22nd.
How did these rare weather phenomena come about? Why is this round of dust weather menacing? How long will the dust last? With questions, Chengdu Business Daily-Red Star News reporters interviewed a number of meteorological experts.
Beijing is now "Blue Sun"
Meteorological Experts:
Particulate matter in the air changes the way light is scattered
Under the influence of sand and dust, the Beijing sky on March 3 showed gray-yellow, and visibility was significantly reduced. At 22:3 on March 22, the Beijing Meteorological Observatory upgraded and issued a yellow warning signal for sandstorms: at present, there has been obvious dust weather in the city, and it is expected that the minimum visibility in most areas will be less than 5,40 meters until noon on the 22nd.
Beijing's air pollution index has also risen. According to the live monitoring released by China Weather Network, the impact of sand and dust in Beijing began from about 22 a.m. on the 3nd to 7 a.m., and the city's average PM10 concentration was 1630 micrograms / cubic meter, reaching a peak and reaching a level 6 serious pollution level.
In addition, data from the China Environmental Monitoring Station show that Dingxi, Datong, Baotou, Hohhot, Baoding, Hengshui, Fuxin and other places also had serious pollution weather on the morning of the 22nd, and the air quality pollution index exceeded 500.
On the morning of the 22nd, many Beijing citizens found that a rare "blue sun" appeared in the sky of Beijing. As for the reason for the formation of the "blue sun", a meteorological expert who did not want to be named told reporters: "This is mainly caused by sand and dust weather." ”
The meteorological expert told reporters that due to more dust, particles in the air will appear "Mie scattering" of light (that is, when the diameter of particles in the atmosphere is comparable to the wavelength of radiation that occurs), under the scattering effect, the particles in the air absorb the red light emitted by the sun, so the sun seen by people through the sun loses its original brightness, and the overall color is gray-blue. According to the expert, this is a common natural phenomenon under the influence of sand and dust.
The reporter checked the official information and found that on April 2022 and December 4, 21, Beijing also suffered from sandy and dusty weather, and the sky repeatedly appeared a "blue sun" process. The above-mentioned experts also warned: "The public should try to avoid looking directly at the 'blue sun' with the naked eye, long-term viewing will cause certain damage to the retina." ”
Changchun now "mud rain"
Meteorological Experts:
Sand and dust fall, and cold and warm air meet to form muddy rain
Changchun, Jilin has also recently suffered from sand-and-dust weather. According to local media reports, on the morning of the 22nd, Changchun was shrouded in darkness. Sporadic rain mixed with dust, falling on pedestrians to form dirty mud spots. Outdoor vehicles are covered in mud.
The reporter saw on the official website of the Jilin Provincial Meteorological Observatory that the Jilin Provincial Meteorological Observatory also issued a cold wave blue warning signal on the morning of the 22nd: It is expected that in the next 24 hours, the minimum temperature in the north of Changchun City, Siping City, Liaoyuan City, Jilin City, and Tonghua City will drop by about 8 °C, and in some places it can reach more than 10 °C.
For the cause of the local "mud rain" phenomenon, the above-mentioned meteorological experts told reporters that this is because Changchun has encountered cold air and dust weather at the same time, cold air sinking drives sand and dust in the air to fall, and at the same time rainfall is formed under the combination of local warm air, so the rain is accompanied by sand and dust to form the "mud rain" phenomenon.
According to the meteorological expert, due to the high latitude area, from March to May every year, there will be cold and warm air convection in many places in Jilin, which has caused the local wind climate process to often occur in spring. Coupled with the withering of surface vegetation in winter, it is easy for sand and dust to enter Jilin Province.
The reporter also learned that this is the second time that Jilin has encountered obvious sand and dust weather this year. According to the Jilin Provincial Meteorological Observatory, in the future, there will be sandstorm processes in parts of the central and western parts of the province.
At 22:7 on the 55nd, the Jilin Provincial Meteorological Observatory issued a blue warning signal of sand: it is expected that in the next 24 hours, the wind in the north of Baicheng, Songyuan, Changchun, Siping, Liaoyuan, Jilin, and Tonghua will still be large, and there will be sandstorms, sandstorms, floating dust and other dust weather, poor visibility, the Provincial Emergency Management Department and the Provincial Meteorological Bureau jointly remind attention to do a good job in wind, dust, fire and other work.
The Jilin Provincial Meteorological Observatory also pointed out that high winds and cold air are conducive to the dissipation of sand and dust weather, and it is expected that this round of sand and dust weather will weaken and tend to end on March 3.
Since March, China has had four times of sand and dust weather
Expert: The sand source has high temperature and little rain, and cold air intrusion causes sand and dust weather transmission
"Today is expected to be a period of heavy sand." At 22 o'clock on the 6nd, the Central Meteorological Observatory continued to issue a gale cooling forecast and a yellow warning of sandstorms: it is expected that from 22 o'clock on the 08nd to 23 o'clock on the 08rd, there will be sand or floating dust weather in parts of Ningxia, most of Inner Mongolia, most of Shaanxi, Shanxi, Hebei, Beijing, Tianjin, central and western Heilongjiang, central and western Jilin, Liaoning, Shandong, Henan, northern Jiangsu and other places.
Among them, there are sandstorms in parts of southeastern Inner Mongolia, Beijing, northern Tianjin, north-central Hebei and other places, and strong sandstorms in local areas.
Is there a significant amount of sand and dust this year? In this regard, Zhang Tao, chief forecaster of the Central Meteorological Observatory, gave an affirmative answer. "Since March this year, there have been four sand and dust weather processes in China, which is more than the same period of the year."
So, what causes the spring dust? Zhang Tao told reporters that the reason for the sand and dust weather is because the current land is warming up, the sun makes the surface loose, and spring happens to be the season of frequent cold air and winds, so when the strong wind passes through Mongolia and the sand source of western Inner Mongolia, Gansu and other places, it will roll the sand and dust into the air, and with the low air flow to the east to the south, affecting the east and south of Inner Mongolia and other areas.
"Since March this year, the sand source has been warm and rainy, and most of the surface is basically free of snow cover, once there is cold air intrusion, there will be windy weather, which is easy to cause sand and dust weather transmission." Zhang Tao said.
According to the reporter's statistics, every year in March ~ May, it is the high incidence period of sand and dust in northern China. The data show that from 3 to 5, there were 2000 large-scale severe sandstorm weather processes in China, with an average of about 2020.32 per year, mainly in March and April (1 in March and 5 in April), and the most frequent years occurred 3 times (4, 3, 11). From March 4 to 14, 5, northern China experienced its strongest sandstorm in a decade, affecting more than 2001.2002 million square kilometers.
Will the dust weather continue in the future? Zhang Tao said that since March, there have indeed been more sand and dust weather, but if we look at the situation throughout the spring, we still need to pay attention to the weather changes in April and May in the future.
Chengdu Business Daily-Red Star News reporter Yang Yuqi Zhang Yanliang reported from Beijing