Causes of dust weather formation

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 hazards 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.