Dareeraha, labadaba dareere iyo gaas, waxay leeyihiin heerar kala duwan oo viscosity ah. Viscosity asal ahaan waa xoogga is-jiidjiid ee u dhexeeya molecules-ka sameeya dareeraha. Moleekuleyaasha sameeya dareeraha ayaa isku xoqa marka ay socdaan. Dareeraha, viscosity waxaa sababa isku-xidhnaan (soo jiidashada u dhaxaysa molecules-ka isku midka ah). Gaasaska, viscosity waxaa sababa isku dhacyada u dhexeeya molecules-ka.
Dareeraha dareeraha ah badanaa si fudud ayay u socdaan, tusaale ahaan biyaha. Taas beddelkeeda, dareerayaasha qaro weyn way adag tahay in la qulqulo, tusaale ahaan saliidda karinta, saliidda, malabka, iwm. Waxaad tan ku caddeyn kartaa adigoo ku shubaya biyo iyo saliid karinta sagxad jilicsan. Biyuhu si hubaal ah ayay uga dhaqso badan yihiin saliidda karinta ama saliidda karinta. Dheecaanka dareereha sidoo kale wuxuu ku xiran yahay heerkulka. Heerkulka dareeraha oo sarreeya, dareeraha oo yaraada. Tusaale ahaan, marka hooyo kalluun ku shiisho jikada, saliidda karinta ee bilowga ah ee qaro weyn waxay noqotaa dareere badan marka la kululeeyo. Taas beddelkeeda, heerkulka gaaska oo kordha, gaaska oo sii weynaada ayaa sii weynaada.
Moleekulada dareeraha ah waxay caadi ahaan is soo jiitaan. Gudaha dareeraha, moleekulada dareeraha ah waxaa ku wareegsan moleekulada kale dhinac kasta; laakiin dusha sare ee dareeraha, waxaa jira moleekulada dareeraha ah oo keliya dhinacyada iyo hoosta. Ma jiraan moleekulada dareeraha ah ee kor ku yaal. Sababtoo ah moleekulada dareeraha ah ayaa is soo jiidanaya, waxaa jira xoog saafi ah oo eber ah oo ku yaal moleekulada gudaha dareeraha. Taas bedelkeeda, moleekulada dareeraha ah ee dusha sare waxaa soo jiita moleekulada dareeraha ah ee dhinacyada iyo hoosta. Natiijo ahaan, waxaa jira xoog saafi ah oo ku yaal dusha sare ee dareeraha oo hoos loogu jeedo. Sababtoo ah xooggan saafiga ah ee hoos loo dhigayo, dareeraha dusha sare wuxuu u janjeeraa inuu yareeyo aagga dusha sare, isagoo yaraanaya intii suurtagal ah.