Inwaterclouds,clouddropletsaresmalldrops.Theyaremostlyfromcontinuecondensationandcollidingcompoundedlattar.Therefore,inwaterclouds,clouddropletswillincreasetothesizeoftherain,wefirstneedtocloudisverythick,clouddropletsdense,moisturecontentmany,sothatitcancontinuetocondensegrowth;Secondly,inthewatercloudsinsidestillneedtohavestrongverticalmovement,likethiscanincreasemanycollisionscompoundedopportunities.Whileinthinnerandmorestablewaterclouds,clouddropletsnotenoughcondensationandcompoundedgrowthopportunities,cancausecloudy,cloudyday,thegeneralassemblydoesnotrain.
Indifferentpartsofacloud,theclouddropletssizewithinthedistributionisdifferent,causingclouddropletsunevensizeofthereasonforthisisthatthetransferofmoistureintheairaroundwhichclouddropletsofevaporationand.Thatclouddropletsgrowthfactoriscongealsandcollisionandprocess,inonlycondensationrole,underthesituationofclouddropletssizeisuniform,butbecauseoftheaddedtomakesomewatervaporclouddropletsincreased,plusandandfunctionoftheresults,thelargerclouddropletscontinuetogrowbiggerberain.Raindropssuffertheeffectofgravityanddecline,whenthereareupdraft,youwillhaveaupwardforceisappliedintherain,makeitsdecliningspeedslowing,andafewsmallrainmayalsobebroughtup.Onlywhenraindropsincreasestoacertainextent,tofalltotheground,intorain.