In meteorology, sand and dust weather is divided into () five levels according to the wind speed and the impact on horizontal visibility.
In meteorology, sand and dust weather is divided into five levels: floating dust, blowing sand, sandstorms, strong sandstorms and extremely strong sandstorms based on wind speed and impact on horizontal visibility.
Sand dust sources provide the material basis for sandstorms. The dust in my country's sandstorms mainly comes from the deserts in southeastern Mongolia and southeastern Kazakhstan, as well as the Hunshandake Sand Land and Alxa in eastern Inner Mongolia. The Badain Jaran Desert in the League, the Taklimakan Desert in southern Xinjiang, and the Kurbantonggut Desert in northern Xinjiang are among the most popular.
It can be seen that the sources of sand and dust are mainly concentrated in the north, which is why sand and dust weather always occurs in the northern region. Especially in the southern Xinjiang Basin, central and western Inner Mongolia, and central and northern Gansu, the average number of sandstorm days per year can reach more than 10 days.
Strong winds and unstable atmospheric formation provide driving conditions for sand and dust weather. They mainly determine the intensity, movement path and duration of sand and dust weather. Unstable atmospheric stratification is conducive to the increase in wind power and the development of strong convection, thereby entraining more sand and dust and carrying it higher.
The above factors can explain why sandstorms occur more often in spring. In spring, there is less vegetation coverage and less precipitation. The soil surface is dry and loose, which is a good source of dust. In addition, cold air activities are more frequent in spring, and accompanied by strong northwest winds, it is easy to produce sandy and dusty days in the unstable atmospheric stratification state in the afternoon.
As a highly disastrous weather, sandstorms have many impacts. Sand and dust block sunlight, causing reduced visibility and seriously affecting traffic safety; gloomy skies can easily make people feel depressed and reduce work efficiency; the amount of respirable particulate matter in the atmosphere has increased, exacerbating air pollution and posing a threat to human health. In addition, the sandstorm process will also intensify soil wind erosion and desertification, causing serious damage to the land productivity of farmland and pasture.