Based on the data of cloud amount during 1951－2007 from seven weather stations in Tianshui，the variation of the total cloud amount and low cloud amount was analyzed，and also the relationship between cloud amount and interrelated climatic factors was discussed．The results showed that the mean total amount of cloud varied little and mean amount of low cloud increased by 0．25%every ten years since 1951．The rainy days with different rainfall level correlated well with cloud amount．It also indicated that the precipitation varied with cloud amount，the annual precipitation increased by 156 mm when annual mean cloud amount increased by 10%．
When seasonal mean cloud amount increased 10%，the precipitation increased by 25 mm，75 mm，35 mm and 3．8 mm in spring，summer，autumn and winter，respectively．When the cloud amount increased by 10%，the mean temperature in spring and summer decreased by 0．6℃and 0．5℃，but there was no correlation between cloud amount and mean temperature in winter and autumn．The sunshine hours was seriously influenced by cloud amount，when cloud amount increased by 10%，the sunshine hours decreased by 102．2 h in spring，90．8 h in summer，87．7 h in autumn and 65．3 h in winter．There was positive correlative between mean cloud amount and relative humidity，when cloud amount increased by 10%，the relative humidity increased by 4%in summer，3%in spring，autumn and winter．The days with＞80%cloud amount reduced year by year in spring．

Based on the data ofwheat stripe rust observation, the meteorological data from seven weather stations and the data ofwinter wheat growth periods in different districts of Tianshui during 1994 - 2006, the characteristics ofwheat stripe rust development and the relation between meteorological factors and winterwheat growth period were analyzed with the method of statistics. The results show that the occurring area ofwinter stripe rust p resented linear increase trend after 1994 with the globalwarming. The ep idemic of stripe rust depends on both localmeteorological condition and stripe rust develop ing trend in periphery area. The model for the stripe rust forecast wasmade and this p rovide some help for active p revention of stripe rust and scientific decision of winterwheat p roduction.

 Based on acid rain monitoring data of 11 years in Xifeng climatologicaL station, and main pollutant source data samples in north  of  Qingyang  city,  according to  acid  rain  monitoring  standard  made  by  China  Meteorological  Administration,  acid  rain ChaTaCteTlSt1CS  WPTe  analyzed  StatlStlCally.  ReSLI1tS  S110W  that  aCld  Taln  degree  Weakened  Wlth  f1LICtllatlOn  dLITlng  1992 -2000  In Qlngyang Clty and hOOSted Llp dLITlng 2001-2002  WlthOllt COriSldeTlng 1T1f1LIenCe Of  Wlnd adVPCtlOn, the fTeqLIenCy OCCLITTlng aCld Taln In a year deehned  yearly,  the  monthly  aC1d  Ta1n  degTPe  1S  maXlmlnn  1n  MaTCh  and  t}OVPlnher,  PH V 0.4c},  the  freC(Lleney  OCCLITrlng  aCld Taln 1S maXlmlnn Of 24%-3Jr}10 from ALIgLISt t0  t}OVPlnher.  COriSldeTlng the  1T1f1LIenCe Of  Wlnd adVPCtlOn In OT hefOTe  Taln,  the 1T1f1LIenCe of pollutant source in the north on yearly acid rain intensity isn't obvious, but it can  make the frequency occurring acid rain increase m a year mainly in the influence on acid rain degree is marked in October, PH reduced 0.3, the influence on monthly acid rain summer. The study revealed the fact that acid rain exists over
Longdong loess plateau, it has an active meaning occurrmg 1S to cure acid rain harm and to protect ecology environment.

Based on analysis of phenological features and metorological conditions during the growing period of prosomillet in Gansu province，the main agrometeorological facts that influence on the growth of prosomillet have been found out and discussed.The influences of meterological factors on the yield of prosomillet has been analyzed with statistical methods.The complex in dices system of ecoclimate regionalzation for planting prosomillet in Gansu province has been given，and the suitable regions have been pointed out，the fit
and unfit conditions in different regions have been commented.