简介：BasedondataofradiationfogeventsinXuanen,Hubeiprovince,2010,thispaperanalyzesthemicrophysicalprocessandevolutioncharacteristicsofradiationfogswithcomplicatedsubstrateintheupperandmiddlereachesoftheYangtzeRiver,andcomparesthemwithfindingsinotherareas.Resultsareasfollows:radiationfoginXuanenisevidentlyweakerindropletnumberconcentrationandliquidwatercontentthanlandfogsinotherareas.Itsliquidwatercontentfluctuatesobviously,0.01g/m3withvisibilityof1,000meters,whichisquitedifferentfromthatinurbanareas,butsimilartotheNanlingMountains.Bi-modaldropletdistributionislikelytooccurinXuanenmountainradiationfog(MRF)events.StatisticalanalysisshowsthattheobserveddropletsizedistributioncanbepiecewisedescribedwellbytheGammadistribution.Thereisapositivecorrelationbetweenliquidwatercontent,fogdropletconcentrationandmeanradius,especiallyinthedevelopmentanddissipationstage.CondensationgrowthanddropletevaporationaremajorprocessesofXuanenMRF.Thedissipationtimecoincidedwiththetimewhenthegrasstemperaturereachedthepeakvalue,whichindicatedthatdewevaporationisakeyroleinmaintainingXuanenMRF.Intheearlystageofdensefog'sgrowth,dropletswithdiameterofover20micrometerscanbeobservedwithvisibilityof800-1,000m,whichmightbecausedbythetransportationoflowclouddropletstoearth'ssurfacebyturbulence.Bigdropletsintheinitialstagecorrespondtohigherwatercontent,leadingtothehigherobservedvalueofwatercontentofXuanenMRF.