Based on conventional meteorological observation data, FY4A satellite data, vegetation cover data and reanalysis data, the formation mechanism, transmission characteristics and influencing factors of a largescale severe dust storm occurring from March 14 to 18, 2021 in northern China were analyzed. The results are as follows: (1) Drought, high  temperature, less rainfall and low vegetation coverage in the earlier period in most parts of northern China provided a good sand source condition for occurrence of the strong sand dust storm weather. (2) The dust weather was caused by the strong development of Mongolia cyclone and the combined action of cold high pressure behind it. (3) The dust weather process was divided into two stages. At the first stage it was caused by the strong winds passing behind the ground cold front, which mainly occurred in North China and Northeast China. At the second stage it was caused by the southward diffusion of highaltitude dust that did not dissipate at the early stage and the backflow of east wind, which mainly occurred in Northwestern China. (4) The analysis of physical quantities such as horizontal helicity, the mixing layer height and vertical velocity showed that the dust emission conditions were insufficient in most areas of China, so the sand dust weather was mainly affected by the upstream sand dust transportation. For the eastern region of China, the contribution of dust storm was mainly from the southern part of Mongolia. While in Northwest China it was mainly contributed by Mongolia and its own dust.

The characteristics of precipitation and lightning activity of a strong hailstorm occurring in Gansu Province on 25 August 2012 were studied by using the data from precipitation radar (PR), microwave imager (TMI) and lightning imager sensor (LIS) boarded on the TRMM (tropical rainfall measuring mission) satellite. The results show that there were three dispersed meso-β scale convective systems by analyzing the horizontal structure of the hailstorm. Although the pixel points of convection precipitation were less than that of stratiform precipitation, the averaged rain rate of convective precipitation was 8.2 times larger than that of stratiform precipitation. The top of the hail cloud could reach up to 13 km above ground with strong echoes (>55 dBZ) below about 7.5 km. The cloud thickness with the precipitation rate greater than 45 mm·h-1 was 7 km. The vertical distribution of precipitation profiles under different rain rates showed inhomogeneous characteristic. The precipitation rates of 50 mm·h-1 and 10 mm·h-1  increased first at lower levels and then decreased with the increase of height，their initial reduced height was about 9 km. Analysis of lightning activity of the hail precipitation process showed that most lightning flashes occurred near the strong convective region with radar echoes higher than 40 dBZ and polarization corrected brightness temperature of 85 GHz channel was lower than 210 K.