Dust weather news in southern Xinjiang

On March 30th, the Central Meteorological Observatory issued a blue warning of sandstorm, which lasted until April 1. Sandstorms should be familiar to us (especially northerners), and many people must be impressed by the "refreshing" earthy smell. So, which areas will this dusty weather hit? How is the sandstorm grade divided? What is the reason for it? How to deal with it?

1. Which areas will be affected by this dusty weather?

With the recent arrival of strong cold air, windy and dusty weather followed. The Central Meteorological Observatory issued a blue warning of sandstorm on March 30th 18, and then on March 30th1,sandstorms or floating dust occurred in central Inner Mongolia, central and western Liaoning, southern Hebei and southern Xinjiang, and sandstorms occurred in Mandula Meteorological Observatory and Erenhot, Inner Mongolia, with visibility less than 300m.

At 06: 00 on April/KLOC-0, the Central Meteorological Observatory continued to issue a blue warning of sandstorms. It is estimated that from 08: 00 on April 6 to 08: 00 on April 2, there will be sand or floating dust in parts of Xinjiang Nanjiang Basin, central and eastern Inner Mongolia, western Liaoning, central and western Jilin, southwestern Heilongjiang, northern Hebei and Beijing, and there will be sandstorms in Xinjiang Nanjiang Basin.

From 08: 00 on the 2nd to 08: 00 on the 3rd, there were 4 ~ 6 winds in most parts of Inner Mongolia, North China, Huanghuai and other places, and there were sand or dusty weather in eastern Inner Mongolia, western Gansu and southern Xinjiang basin.

The picture comes from the Central Meteorological Observatory.

2. How is the level of sandstorm divided?

In our daily life, whenever the weather is windy in Sha Fei, we all think that sandstorms are coming, but they are not. As a disastrous weather phenomenon, sandstorm has strict definition and classification, and not all sandstorms are called sandstorms.

The dictionary of atmospheric science defines sandstorm as a weather phenomenon in which strong winds blow up dust on the ground, making the air very turbid and the horizontal visibility is less than 1 km. So, what is the dusty weather with visibility greater than 1 km?

According to the visibility, the meteorological department divides sandstorm weather into five categories: floating dust, sand blowing, sandstorm, strong sandstorm and extra-strong sandstorm. Among them, floating dust refers to the weather phenomenon that dust and fine sand float evenly in the air, making the horizontal visibility less than 10 km; Sand blowing is a weather phenomenon that the wind blows up dust on the ground, making the air turbid, and the horizontal visibility is 1 ~ 10 km. Sandstorm refers to the weather phenomenon that strong winds blow up a lot of dust on the ground, making the air very turbid and the horizontal visibility is within 500 ~ 1000 meters; Strong sandstorm refers to the weather phenomenon that strong winds blow up dust on the ground, making the air very turbid and the horizontal visibility less than 500 meters; Extra-strong sandstorm is a dusty weather phenomenon in which strong winds blow up a lot of dust on the ground, making the air particularly turbid and the horizontal visibility is less than 50 meters. In this sandstorm weather, only Inner Mongolia and Xinjiang have sandstorms, and other areas have sand blowing or floating dust weather.

3. What is the cause of sandstorm?

We know that to form a sandstorm, there must be sand dust first, and then there must be strong wind, which can be said to be "the lingering of sand dust."

Dust is the material basis of dust storms. The sources of sandstorms affecting China can be divided into domestic sources and overseas sources. The overseas source areas mainly include Gobi desert in southeastern Mongolia and desert in southeastern Kazakhstan; China's source areas mainly include the central and western Hunshandake sandy land in eastern Inner Mongolia, the border area between China and Mongolia in Alashan League (Badain Jaran Desert), the Taklimakan Desert in southern Xinjiang and the Tonggut Desert in Kurban Banner in northern Xinjiang. Strong wind is the power source of sandstorm formation. With it, sandstorms can cross the ocean for a long distance. Unstable thermal conditions are conducive to the increase of wind power and the development of strong convection, thus carrying more dust and making it "fly higher".

Generally speaking, drought, lack of rain and high temperature in the early stage are the weather and climate background of sandstorm weather. In addition, the formation of dusty weather is not unrelated to human activities. Excessive cultivation, overgrazing and firewood harvesting by human beings have caused the rapid expansion of vegetation destruction, soil exposure and land desertification, and also promoted the formation of dusty weather to some extent.

desertification

4. What's the difference between sandstorm and smog?

Sandstorms and haze will cause "grayish yellow" sky and reduce visibility. However, they are two different weather phenomena.

First, the composition of "raw materials" is different. Sandstorm weather is mainly composed of dust aerosol, while haze weather is mainly composed of aerosol components composed of pollutants in addition to the influence of dust aerosol. Secondly, the meteorological conditions of the two are different, that is, "one move and one silence": the meteorological conditions of dust are atmospheric instability, strong winds blow a lot of dust on the desert surface along the way, and there is settlement during transmission, and dust weather appears along the way; The meteorological conditions of smog are that the atmosphere is still, the air mobility is poor, and the pollutants in the atmosphere cannot spread. Thirdly, they visit in different seasons, and the dusty weather is seasonal, mainly in spring; Haze can appear all year round.

Cartography: Zhai Jinsong

5. Is sandstorm bad?

In our impression, sandstorms seem to be useless: affecting travel, polluting the air and endangering health ... In addition, 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 ~ 10 cm, seriously damaging the land productivity of farmland and grassland in the source area.

However, everything in the world is divided into two. Do you know that dust can not only pollute the air, but also purify it! It sounds contradictory, but it is true. Dust can adsorb human activities, such as industrial dust, sulfur oxide in automobile exhaust, etc., and precipitate impurities in the air, thus playing a role in filtering the air and effectively reducing and inhibiting the formation of acid rain in northern China. In addition, according to experts' research, sandstorms can also restrain global warming to some extent. The dust aerosol of sandstorm is like a sunshade, which blocks solar radiation from entering the earth's surface. At the same time, dust particles can also be used as cloud condensation nuclei to affect the formation, radiation characteristics and precipitation of clouds, thus producing indirect climate effects. These effects can restrain global warming caused by greenhouse effect to some extent.

6. How should we deal with sandstorms?

When it comes to dealing with sandstorms, our first reaction is to plant trees and protect the environment, but this is more from the government level. For us personally, when encountering a certain dusty weather, scientific protection and response will always be the first. Here are some simple suggestions to protect dusty weather:

(1) Close the doors and windows in time, and seal the doors and windows with tape when necessary;

(2) Minimize going out. If you have to go out, wear a mask and cover your head with a scarf to avoid dust invading your eyes and respiratory tract. Wash your face quickly after going home, especially your mouth and nose, and try to prevent dust from being inhaled into your body.

(3) Pay special attention to traffic safety. Motor vehicles and non-motor vehicles should slow down, pay close attention to road conditions and drive carefully.

(4) Outdoor items that are easily damaged by sandstorms should be properly placed.

(Author: Wang Haibo, chief engineer of Meteorological Propaganda Science Center of China Meteorological Bureau, original works, please indicate that knowledge is power from WeChat official account)

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Author: Wang Haibo

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