简介：Thebreakdownandfoundationofgeostrophicbalanceisoneoftheimportantmovementsinthemid-andhigh-latitudeatmosphereandoceans.Inthetropicalarea,thevalueofCoriolispa-rameterissosmallthatitisdifficulttosatisfythebi-geostrophicequilibriumbetweenthepressureandvelocityfields.However,inthetropicalarea,thezonalvelocityofsomemotionsintheatmo-sphereandoceansislarge,sotheCoriolisforceisnotsmall,geostrophicbalancecanexistinzonaldirection,i.e.semi-geostrophicbalance.Furthermore,inthedominantareaofHadleycirculationintheatmosphereortheareaneartheoceanmeridionalboundary,themeridionalvelocityislarge,sogeostrophicbalancecanalsoexistinmeridionaldirection.Inthispaper,theprocessofthedis-persionofinertialgravitywaveandthefoundationofsemi-geostrophicbalancearefirstdiscussed.Second,theadjustmentprocessbetweenthevelocityandpressurefieldsafteradaptationisalsoviewed,andthescalecriterionofthesemi-geostrophicadaptationisdiscussed,i.e.forthemotionwithmeridionalscalegreaterthantheequatorialRossbyradiusofdeformation,thevelocityandpressurefieldsafteradaptationchangetofittheinitialpressurefield;onthecontrary,thefieldschangetofittheinitialzonalvelocityfield,andthestrengthofthefieldsafteradaptationdependsonthezonalscale.