The different level rainy days and its homologous precipitation quantity are obtained by using the daily precipitation data from
May to September ( 1960 － 2004) of 17 stations in the Qilian Mountain area，thus，we know the daily precipitation intensity of light
rainfall and moderate rainfall( and more) at each station． Based on regional mean value of the different level rainy days and rainfall intensity
in Qilian Mountain area，the tendency of the different level rainy days and rainfall intensity was analyzed using linear trend coefficient
and 5 levels main value function． The results show that both precipitation and different level rainy days from May to September
in Qilian Mountain area presented more in the west side and less in the east side in the same latitude area，and more in the east and
less in the west part of Qilian Mountain． In recent 45 years，the light rainfall days was descending，but the moderate rainfall days was
ascending． The precipitation intensity of light rainfall and moderate rainfall ( and more) presented ascending trend too from May to September
in Qilian Mountain area． The morlet wave analysis show that the light rainfall days had a period of five years，but the period of
the moderate rainfall ( and more) days was more complex．

The regional distribution features of daily mean net radiation，sensible heat flux，latent heat flux and soil heat flux density in summer over central Gansu were derived from the Surface Energy Balance A1gorithm for Land(SEBAL)using micrometeorological ob．servations over a wheat field at Dingxi station，solar radiation observations at Dingxi and Lanzhou stations．observations of 34 meteoro-logical。hydrological and rainfall stations over the Maxian Mountain region，combining with NOAA一16 AVHRR data，as well as the land surface reflectance an d vegetation coverage retrieyed from NOAA一16 AVHRR data．the efects of land surface process on precipi．tation were also analyzed in this paper．Th e results show that the regional distribution of annual mean precipitation corresponds well to vegetation coverage in summer。the correlation coeficient is 0．722．and the correlation coeficients of annual mean precipitation and soil heat flux ．1atent heat flux density are 一0．65 and 0．615．respectively．It is showed that the forest can not only increase net radia-tion but also decrease sensible and soil heat fluxes by decreasing surface reflectance and temperature．More solar energy can bere·ceived and mostly used for evapotranspiration over forest regions．which makes vapor content increased there．For this reason precipita—tion over forest regions is much more than that of semi—arid regions with sparse vegetation

The regional distribution features of daily mean net radiation，sensible heat flux，latent heat flux and soil heat flux density in summer over central Gansu were derived from the Surface Energy Balance A1gorithm for Land(SEBAL)using micrometeorological observations over a wheat field at Dingxi station，solar radiation observations at Dingxi and Lanzhou stations．observations of 34 meteoro-logical。hydrological and rainfall stations over the Maxian Mountain region，combining with NOAA一16 AVHRR data，as well as the land surface reflectance an d vegetation coverage retrieyed from NOAA一16 AVHRR data．the efects of land surface process on precipi．tation were also analyzed in this paper．Th e results show that the regional distribution of annual mean precipitation corresponds well to vegetation coverage in summer。the correlation coeficient is 0．722．and the correlation coeficients of annual mean precipitation and soil heat flux ．1atent heat flux density are 一0．65 and 0．615．respectively．It is showed that the forest can not only increase net radia-tion but also decrease sensible and soil heat fluxes by decreasing surface reflectance and temperature．More solar energy can be received and mostly used for evapotranspiration over forest regions．which makes vapor content increased there．For this reason precipitation over forest regions is much more than that of semi—arid regions with sparse vegetation

Based on the hail suppression operation status at present，the tasks of the technique system，the peripheral technique system，the operational conducting system of the hail suppression and the relations among them are discussed in this paper，and also the relative possibility of the general adaption of the operational conducting system and its realizing way and degree for a single radar station or a city. A concept of " rather empty leak not" is given.

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.

Using the data of aircraft artificial precipitation enhancement operation from 1991 to 2002 in Cransuprovince，the situation of it was analyzed statistically in late spring and early summer.  According to the characteristic of weather system of Cransu，making use of sounding data and basing  `discriminant model'，we can educe three types of high一level circulation of precipitation.  These types were straight but some fluctuant，southwest and northwest air current weather system，respectively.  Among the types，the straight but somefluctuant air current weather system emerged morefrequently.  The typesof weather system of aircraft artificialprecipitation enhancement operation were sorted by `discriminant model'，result showed that the main type of aircraft artificialprecipitation enhancement operation was straight but some fluctuant air current weather system also，and the next type was southwest air current weather system.