▁assuming ▁that ▁clouds ▁form ▁at ▁ 1 0 0 % ▁relative ▁hum id ity , ▁the ▁cloud ▁fraction ▁can ▁be ▁related ▁to ▁a ▁critical ▁relative ▁hum id ity ▁of ▁ 7 0 % ▁for ▁str atus - type ▁clouds , ▁and ▁at ▁or ▁above ▁ 8 0 % ▁for ▁cum ul iform ▁clouds , ▁reflect ing ▁the ▁sub ▁grid ▁scale ▁variation ▁that ▁would ▁occur ▁in ▁the ▁real ▁world . ▁ ▁Port ions ▁of ▁the ▁precip itation ▁parameter ization ▁include ▁the ▁cond ens ation ▁rate , ▁energy ▁ex changes ▁dealing ▁with ▁the ▁change ▁of ▁state ▁from ▁water ▁v apor ▁into ▁liquid ▁dro ps , ▁and ▁the ▁micro phys ical ▁component ▁which ▁controls ▁the ▁rate ▁of ▁change ▁from ▁water ▁v apor ▁to ▁water ▁dro ple ts . ▁ ▁Rad iation ▁and ▁atmosphere - sur face ▁interaction ▁ ▁The ▁amount ▁of ▁solar ▁radiation ▁reaching ▁ground ▁level ▁in ▁rug ged ▁terrain , ▁or ▁due ▁to ▁variable ▁cloud iness , ▁is ▁parameter ized ▁as ▁this ▁process ▁occurs ▁on ▁the ▁mole cular ▁scale . ▁ ▁This ▁method ▁of ▁parameter ization ▁is ▁also ▁done ▁for ▁the ▁surface ▁flux ▁of ▁energy ▁between ▁the ▁ocean ▁and ▁the ▁atmosphere ▁in ▁order ▁to ▁determine ▁real istic ▁sea ▁surface ▁temper atures ▁and ▁type ▁of ▁sea ▁ice ▁found ▁near ▁the ▁ocean ' s ▁surface . ▁ ▁Also , ▁the ▁grid ▁size ▁of ▁the ▁models ▁is ▁large ▁when ▁compared ▁to ▁the ▁actual ▁size ▁and ▁rough ness ▁of ▁clouds ▁and ▁top ography . ▁ ▁Sun ▁angle ▁as ▁well ▁as ▁the ▁impact ▁of ▁multiple ▁cloud ▁layers ▁is ▁taken ▁into