In the context of 1982—1994 NCEP/NCAR wind at 12-level isobaric surfaces on a global basiscalculation is made of the barotropic(mass-weighed vertical mean)and baroclinic components(difference between the actual wind at each level and barotropic component)of atmospheric flowfields,followed by dealing with the distribution features of barotropic and baroelinie patternsglobally in winter and summer,alongside with the classification of global monsoons according tothe surface barotropic/baroclinic patterns.Evidence suggests that the seasonal variation of bothcomponents will lead to the reversal of a prevailing wind between winter and summer,thus causinga related monsoon:the baroclinie flow pattern is indicative of a thermal circulation driven byatmospheric inhomogeneous heating chiefly from land-sea thermal contrast whilst the barotropiccounterpart represents the result mainly from dynamic effects,which is helpful to theunderstanding of monsoon nature.And further study shows that the classical monsoon regions intropical Asia,Africa and South America fall into a baroclinic category,those in the bi-hemispheriesubtropical Pacific into a barotropic type and the East Asian subtropical monsoon generated underthe joint action of both the patterns falls into a mixed category.