Meteorology, according to the size of the wind speed and its influence on the horizontal visibility, dust weather is divided into () five grades.

Meteorology, according to the magnitude of wind speed and its influence on horizontal visibility, sandstorm weather can be divided into five grades: floating dust, sand blowing, sandstorm, strong sandstorm and extra-strong sandstorm.

Dust sources provide material basis for dust storms. Sandstorms in China mainly come from deserts in southeastern Mongolia and Kazakhstan, as well as Hunshandake Sandy Land in eastern Inner Mongolia, Badain Jaran Desert in Alashan League, Taklimakan Desert in southern Xinjiang and Tonggut Desert in Kurban Banner in northern Xinjiang.

It can be seen that the dust sources are mainly concentrated in the north, which is why dust weather always appears in the north. Especially in southern Xinjiang basin, central and western Inner Mongolia, central and northern Gansu and other areas, the annual average number of sandstorm days can reach more than 10 days.

Strong winds and unstable atmosphere provide dynamic conditions for dusty weather. They mainly determine the intensity, moving path and duration of dusty weather. Unstable atmospheric stratification is conducive to the increase of wind power and the development of strong convection, thus carrying more dust and rising higher.

Taken together, the above factors can explain why sandstorms often occur in spring. In spring, vegetation coverage is less, precipitation is less, and the surface is dry and loose, which is a good source of dust. In addition, the frequent cold air activity in spring, coupled with strong northwest wind, makes the atmospheric stratification unstable in the afternoon, which is easy to produce dusty days.

As a disastrous weather, sandstorm has many effects. Dust blocks sunlight, reduces visibility and seriously affects traffic safety; The gloomy sky is also easy to make people feel depressed and reduce work efficiency; The increase of inhalable particles in the atmosphere aggravates air pollution and poses a threat to human health. In addition, the sandstorm process will aggravate soil wind erosion and desertification, and cause serious damage to the land productivity of farmland and grassland.