a wave of dust is coming… Remember to wear a mask at work

According to the forecast of Beijing environmental protection monitoring center, a wave of large-scale dust has begun to affect Beijing since yesterday, and the dust may also affect Beijing this morning< This is the second wave of dust weather this year. But you don't have to be nervous. The official microblog of Beijing Meteorological Bureau also reminds us that this sandstorm is not sandstorm, but local sandstorm according to the municipal environmental protection monitoring center, a large range of dust has formed in the Alashan Desert in western 1nner Mongolia and western Gansu in the upper reaches of Beijing the day before yesterday. At present, it has arrived in Ningxia and Northern Shaanxi. According to the monitoring data of air quality, the maximum concentration of PM10 in the dust affected areas has gradually decreased from 865 μ g / m3 yesterday morning. The monitoring data at 11:00 show that the maximum concentration of PM10 is 322 μ g / m3, which is expected to affect Beijing this morning< 1t is predicted that PM10 will become the primary pollutant and the air quality will be at the level of mild to moderate pollution at the same time, during the day, the north wind is obvious, the gust is expected to be about 7, the local sand may be accompanied, and the wind will gradually weaken in the afternoon. According to the forecast of the Ministry of environmental protection, three days from now, the whole country will have favorable conditions for air diffusion. The air quality is mainly good, and some areas may have mild pollution Northwest and North China are likely to be affected by sandstorms. Based on the original forecast, the air quality of some cities may become worse by one to two levels, and there will be short-term moderate to severe pollution floating dust, blowing sand and sandstorm should be distinguished clearly floating dust, blowing sand, sandstorm, the above three weather phenomena belong to the visual range obstacle phenomenon< Blowing sand: the dust and sand on the ground are blown up by strong wind, which makes the air quite turbid, and the horizontal visibility is greater than or equal to 1.0KM to less than 10.0km floating dust: dust and fine sand float evenly in the air, making the horizontal visibility less than 10.0km. Most of the floating dust comes from the dust in the distance spread by the upper air current, or from the fine particles floating in the air after the appearance of dust storm and sand blowing sandstorm: due to the strong wind blowing up a large amount of dust on the ground, the air is quite turbid, and the horizontal visibility is less than 1.0KM. According to the visibility, sandstorm can be divided into three grades: sandstorm (visibility 0.5km ~ less than 1.0KM); Severe sandstorm (visibility 0.05km ~ less than 0.5km); Especially strong sandstorm (visibility less than 0.05km) floating dust appears in the windless or windless hours before and after the cold air passes through, and it spreads from the distant sand dust through the upper air flow. Or by blowing sand or dust storm weather has not yet subsided dust floating in the air. The visibility distance is less than 10km and the vertical visibility is poor sand blowing is due to the local or nearby dust blowing, which significantly reduces the visibility, and the visibility distance is generally 1-10km. The sky is cloudy and the wind is strong. 1n spring and summer in the north, cold air appears when the mirror is over or the air is unstable the cause of sandstorm is similar to blowing sand, but the visibility is & lt; 1km. The wind is strong. 1t is often accompanied by strong convection or thunderstorm the difference between floating dust and blown sand is that blown sand is formed by local or nearby sand, and most of the floating dust comes from far away (it may also be that the dust still floats in the air after blowing sand); The main reason is that the wind is strong and the air is unstable when blowing sand, while the condition of floating dust is small wind or no wind. The main difference between Sandstorm and blowing sand is lower visibility there are two kinds of dust weather in Beijing. One is the external dust, which comes from the upwind of Beijing, such as some sand sources in Mongolia and 1nner Mongolia. After the occurrence of dust weather, the dust will be transported to the downstream and subside, affecting Beijing. The second is local sand blowing. 1f there is a wind greater than level 4 in Beijing, local sand blowing will easily occur when the surface is dry< However, according to experts, the dust weather in Beijing is mainly foreign dust. 70% to 80% of the dust weather in a year occurs in spring, which is mainly related to the characteristics of seasons in addition, dust weather is also an important factor affecting Beijing’s air quality in spring. However, according to the monitoring data from 2006 to 2015, Beijing’s air quality has shown a significant downward trend, and the dust weather has been reduced by half

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