The PMS p robeswere used to measure microphysical parameters of a summer stratus on August 15, 2007 inMinle of Gansu Provinc. The cloud structure including particle’s vertical distribution, liquid water content and particle spectrum type was analyzed.Results show that: (1) the cloud structure of the stratus is clear, and there is an inversion layer in this cloud; (2) the average of liquid water content is 0. 012 g·m- 3 in the cloud, and mainly concentrated in the layers of 4 100 - 4 200 m and 4 700 - 5 000 m; (3)this cloud accordswith the Bergeron’s catalytic cloud and water cloud interaction model, so we can seed crystals to achieve the objective of increasing p recip itation.
The operation synthetical system for hailmonitoring, warning and hail supp ression command in Northwest China consists of four sub - systems, including the hail disaster database, the hailmonitoring system, the hailwarning system and the hail supp ression commanding system. Based on the p resent research results, the system has used the new data from Dopp lerweather radar, satellite remote sensing, lightningmonitoring and so on to build a powerful, convenient and open command p latform for hailmonitoring, warning and supp ressing by the p rimary means of the computer network and software technology. The system is valuable in the operation app lication. And this paper has highlighted the function and the design of the system.
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.
Based on the data measured by PMS and GPS during a cold front process on April 24,2002, the horizontal and vertical distributions and spectrum characteristics of microphysical quantities of cloud drop and ice crystal were analyzed in this paper. And the optimum parameters of simulated functions were given out, the possible microphysical mechanism which involved were discussed. On these facts, the potential ability of enhancement rainfall was discussed and estimated.
By using the lightning data in 2000 and 2002 around Lanzhou，lightning characteristics such as daily variation，spatial density，intensity and polarity of lightning are analyzed and also compared with those in Shandong province.The results indicate that major cloud-to-ground（CG）flashes of lightning are negative.The mean intensity of positive flashes is stronger than that of negative flashes and their ratio is over average during 12：00 to 00：00.Daily variety of the CGand negative flashes is bimodalundulance，other than positive flashes unimodal.The biggest flashes frequency center locates in Weiyuan and Longxi county，and accord with the location of hail source are aand hail affecting zone. Furthermore，the spatial distribution of lightning is closely related to the topography and under lying surface and synoptic climatic background
According to the developmental situation of the artificial rain or snow enhancement in Gansu province.and consulting the domestic or foreign status of precipitation increasing .the paper indicats some scientific problems need to be solved immediately in Gansu province.
