By using thelatest data obtainedfromthe 80 m observingtowerformeteorolo~calfactors detectinginthe hinterland ofTaldi·makan Desert。the evolution characteristics of the wind velocity，temperature an d humidity profiles near the surface layer there on a cloudy day(A 1 2，2006)were analyzed in detail，and these profiles were compared with those ofthe typical sunshiny day there．Re·suits are as follows：(1)On cloudy day，the value of wind speed is increasing with height at night but its change doesn’t obey the loga·rithmic law，it grows at a faster rate；in the daytime the wind spe ed is small，the distributions of wind velocity profiles above and below 10 m near the surface layer are rather diferent at each o~ervational time；(2)Observed temperature profiles on cloudy day age classi·fled into four types：radiation coling at night。transition from night to daytime in early morning，insolation in the daytime，transition from daytime to night，respectively，they are similar to those of sunshiny day；(3)There is a minimum in spec~c humidity profiles，a·beve the height where the minimum appears the specie humidity rises with height increase and appears a”moisture inversion”phe·nomenon，and below that height the specific humidity rises with height decrease．

Desertific;ation is one of the most serious ec;ologic;al} social and economic; problems in arid and semi一arid regions in the con-
temporary world.  Based on referring to a large amount of literature we have narrated and(ommented the concept of desertification in
detail and its  connotation from time spac content  landscape  development tendency and results of sandy desertification in this arti-
cle and have particularly outlined the domestic and foreign desertific;ation monitoring appraisal target system}graduation and its distri-
bution in the world. On one of the focal arguments point of the(auses of desertification} we have synthesized various viewpoints and fi-
nally summarized as natural reason and artificial reason such as drought climate, gale and unreasonable human being's”six excesses"
activities.  Simultaneously controlling methods, basic  we have outlined the interaction ways of desertific;ation and some
Between global warming and desertification. In the end， the preventing and questions like these have also been summarized systemically