b"Figure3 150-;,.rr-r-,,:-..-, 1 OCT1962 .3 l.BLACKINSULATED 2.WHITEINSULATED 1253.AMBIENT -~ 0 100 I.LI a:: . :) ~I a:: - 3.D ~75 - w- - ~I w Cl- - -~2 .,_ ', ', ', .- J 50-_,___.__ _.__ 25'-________.___.__________.________________ 1200130014001500160017001800190020002100.2200 TIMEOFDAY Thedegreeoftemperaturechangetowhichamembraneissubjecteddependsuponthethermalreflectance oftheroofsurface .DataobtainedduringtestsattheNationalBureauofSt andardsshowthat .the black-coveredmembranewassubjectedtotemperaturefluctuations2-1/2timesgreaterthanthei'Jhi tecoveredmembrane.Therightsideoft hegraphshowssub-cooling,i.e.,rooftemperatureislessthan .thetemperatureoftheambientair.Thegraphshowsthatsub-coolingdoesnotdependuponcoloror textureofthesurfaceasbothsurfacesrecordedessentiallythesametemperature."