Abstract: Based on the NCEP reanalyzed daily data, the observation data of the meteorological stations and sandstorm monitoring stations in Inner Mongolia, a snow and dust weather process on February 21, 2015was analyzed in the Yinshan Mountains in Inner Mongolia. The results indicated that the process is affected by the strong cold air and the rapidly increased Mongolia cold vortex. There were snow in the cold front area and snowstorm in the large wind zone. The sandstorm weather occurred, as the wind speed strengthened in the secondary cold front area. There were some differences between the snowstorm and sandstorm in this process. (1) The same affecting systems were the cold vortex and cold front, the snowstorm appeared in the front and warm front area, but the sandstorm was controlled by the strong cold advection in the rear of the front. (2) The relative humidity was more than 70% in the snowstorm process and the relative humidity was less than 30% in the sandstorm process. (3) The unstable stratification was more important in the sandstorm process than in the snowstorm process. (4) The air temperature suddenly dropped in the snowstorm process, but there was a gentle, but steady, downward slide in the sandstorm process.

Key words: sandstorm, snowstorm, PM₁₀