The change of the 0℃level height in summer over the northeast side of the Qilian Mountain was analyzed, and the relationshipbetween the 0 `C; level height and surface temperature, precipitation, water vapor content in atmosphere and stream flow of inland rivers were discussed. Results show ; (1) The 0℃level height was obviously higher than normal in the late 1950s and the 1960s, and lower in the 1980s. It presented downward irend from the late 1960s to 1970x, and upward trend in the 1980s and 1990x, and it downward again in the first 4 years of the 21 s2 century; ( 2 ) From May to September, the positive correlation was found between the 0℃level height and surface temperature, water vapor content in atmosphere, and it was negatively correlated with precipitation, and there was low correlation

The characteristics of Doppler radar echoes and products in the artificial rainfall enhancement operation in the middle section of the Qilian Mountain on July 1st，2005 were analyzed in this paper by using radar data. It shows that the large scale weather background which resulted in large range rainfall echoes keeping for long time，and weather modification caused this rainfall process together，and the intensity and the velocity fields present the mixed precipitation echo characteristics，especially remarkable during the rainfall enhancement phase. Results show that the convergence flow field on the velocity image，wind profile products and vertical integrated liquid water content（VIL）have specific instruction significance to prediction of rainfall area and rainfall moving system as well as ground precipitation；the 0 ℃ layer bright band on the base reflectivity image and the convergence flow field on the velocity image are important basis for rain enhancement opportunity and position. The spatial - temporal distribution characteristics of precipitation along the different heights above sea level in the mid - section of Qilian Mountain provide the study basis for examining the effects of rain enhancement. Additionally，the precipitation process was analyzed from the synoptic meteorology and physical quantity diagnoses in the paper.

Using the lightning position network and Doppler radar data, a hailstorm occurred on May 15，2004 over Gaolan county of Lanzhou city has been analyzed，especially, the relationship between lightning evolution and radar echo feature as well as cloud characteristic parameters of the thundercloud was discussed in detail，then the lightning mechanism and the structure of electric field of thundercloud have been analyzed.
A case study of the hailstorm in Uaolan county indicated that if there was the maximum region of cloud liquid water content, then it could be an important factor to identify the beginning of hail falling. The  total lightning and cloud lightning presented linear distribution over the moving track of the
ground lightning concentrated in hail falling zone the most ground lightning was minus.hc analysis thundercloud，and the results show that the
cloud precipitation efficiency and cloud water content Were sensitive to generating lightning.

Using the synoptic chart and Doppler radar data to analyze the weather case on Sep. 18, 2003, when we served for the tenth ann1VCTSary  CelehTatlOn  Of  the  1}ariZhOl1  ReglOnal  1V1eteOTOlOglCal  Center ,the  TCSLI1tS  S110W  that  the  COriVentlOnal  Weather  data  WlthOllt
COntlnlnty Cannot he LISed t0 fnreeaSt the  Small meSOSCale  System hl}e th1S Ca.Se}hllt LISlng Doppler radar data Can fnreeaSt the 1nflLIenCe
of the synoptic system by analyzing the change of the radial wind field.