The study of summer rainfall characteristics in the middle of the Qilian Mountains can provide weather background support for artificial precipitation enhancement by terrain clouds. Based on hourly surface meteorological observations and Temperature of Black Body (TBB) from FY-2G satellite during 2015-2017, the characteristics of rainfall and convection in summer and relationship between diurnal variation of rainfall and local circulation are investigated. The results show that the total rainfall amount of meteorological stations with an altitude less than 3.5 km in the middle of the Qilian Mountains increases linearly with the altitude, and in the eastern part (east of 99.2°E) it changes more sharply with the altitude than that in the western part. The diurnal variation of valley wind circulation and rainfall at Yeniugou and Qilian stations in the valley is more obvious than that at Gangcha Station near the Qinghai Lake. The maximum and sub-peak of rainfall at the two stations are in the evening and early morning, respectively, corresponding to the high frequency periods of the two main topographic clouds (cumulonimbus and stracumulus) in the region, and the average rainfall intensity is 2.0-2.3 and 1.0-1.3 mm·h^-1, respectively. Compared with Zhangye Station in Hexi Corridor, the peak value of TBB probability distribution at Qilian, Yeniugou and Gangcha stations in the Qilian Mountains changed from -22--12 ℃ to -32--22 ℃ under two kinds of rainfall intensity (less than 1.5 and more than or equal to 1.5 mm·h^-1). When the threshold of TBB <-32 ℃ is used to identify rainfall cloud, the coverage rate of rainfall cloud in the Qilian Mountains is lower than that in Hexi Corridor. The threshold of TBB <-22 ℃ is more suitable for the identification of weak convective rainfall clouds in the Qilian Mountains. In the study area, the high value areas of deep and shallow convection are distributed in the direction of north-south and northwest to southeast, respectively. The diurnal variation of shallow convective frequency based on TBB data can reflect some characteristics of diurnal variation of rainfall in this region.

In order to deeply understand the evolution and driving factors of extreme dust events, two dust storm events that erupted in the deserts and gobi regions in the arid regions of northwest China on 31 March 2007 (“3·31” dust event) and 14 March 2021 (“3·14” dust event) were selected, and their temporal and spatial evolution, high and low altitude circulation configuration, and changes in near-surface meteorological elements were compared and analyzed based on multi-source satellite remote sensing and reanalysis data. The results are as follows: (1) Both extreme events occurred in the Taklimakan Desert and the Gobi Desert, respectively, and they were influenced by upper-and-lower weather systems. The“3·31” dust event was influenced by a surface cold front and a ridge at high altitude. The northwesterly winds in front of the ridge, in cooperation with the vertical motion caused by the cold front, transported dust downstream. The “3·14” dust event, on the other hand, was influenced by a Mongolian cyclone and an upper-air trough. The northwesterly winds following the cyclone, along with the vertical motion induced by the cyclone, swept up dust and transported it downstream through the northwesterly winds following the trough. (2) Both extreme dust events exhibited prolonged durations. The “3·31” dust event was influenced by the high-pressure ridge, a sea level pressure field with little variation and the surrounding topography. This configuration resulted in a stable atmosphere, preventing the deposition and transport of dust. Different from the event above, the “3·14” dust event was caused by the persistent high pressure over northern China, which led to southerly and easterly winds that prevented dust spreading downstream. (3) Before occurrence of the extreme dust events, both the Taklimakan Desert and Gobi Desert experienced high temperature, less precipitation, and depleted soil moisture, which formed favorable dynamic conditions and material foundations, such as strong winds and dry soils, for the outbreak of the two dust events.

After deducing external trajectory calculation method under non-standard atmospheric conditions for 37 mm anti-aircraft gun, which was widely used in the field of weather modification, the ballistic data in uniform cross wind and range wind field were simulated. The results show that the wind made a great influence on the flight path of projectile. The range wind can change the ballistic range by affecting the size and direction of air resistance. The cross wind can generate a lateral deviation of the trajectory along the wind by affecting the direction of the air resistance. On the same launch elevation angle, with the change of wind speed, the trajectory deviation correction caused by cross wind and the range correction caused by range wind showed a variation law that was similar to arithmetic progression. Through fitting analysis, the relationship among wind speed, elevation and trajectory correction was obtained，which can be used to estimate trajectory correction under arbitrary wind speed in actual operation.

This paper analyzed the influences of dust aerosols on cloud properties and TOA radiative forcing in the process of the duststorm for the period of March 26 to 28 ,2004 over Northwest China, using data collected by MDDIS( Moderate Resolution Imaging Spec-troradiometer) and CERES( Clouds and the Earth's Radiant Energy Budget Scanner) instruments on the Aqua satellite. These dust aero-sols decrease the ice diameter,optical depth and ice water path of clouds. Thus, the TOA  net radiative forcing of clouds is reduced.This means that the cooling effect of clouds is restrained.