▁of ▁polar ization ▁however , ▁does ▁not ▁always ▁remain ▁consistent ▁and ▁may ▁in ▁fact ▁decrease ▁in ▁different ▁situations . ▁The ▁Ray le igh ▁sky ▁may ▁under go ▁dep olar ization ▁due ▁to ▁nearby ▁objects ▁such ▁as ▁clouds ▁and ▁large ▁reflect ing ▁surfaces ▁such ▁as ▁the ▁ocean . ▁It ▁may ▁also ▁change ▁depending ▁on ▁the ▁time ▁of ▁the ▁day ▁( for ▁instance ▁at ▁tw il ight ▁or ▁night ). ▁ ▁In ▁the ▁night , ▁the ▁polar ization ▁of ▁the ▁moon lit ▁sky ▁is ▁very ▁strongly ▁reduced ▁in ▁the ▁presence ▁of ▁urban ▁light ▁poll ution , ▁because ▁scattered ▁urban ▁light ▁is ▁not ▁strongly ▁polar ized . ▁ ▁Ext ensive ▁research ▁shows ▁that ▁the ▁angle ▁of ▁polar ization ▁in ▁a ▁clear ▁sky ▁continues ▁under ne ath ▁clouds ▁if ▁the ▁air ▁beneath ▁the ▁cloud ▁is ▁directly ▁lit ▁by ▁the ▁sun . ▁The ▁scatter ing ▁of ▁direct ▁sun light ▁on ▁those ▁clouds ▁results ▁in ▁the ▁same ▁polar ization ▁pattern . ▁In ▁other ▁words , ▁the ▁proportion ▁of ▁the ▁sky ▁that ▁follows ▁the ▁Ray le igh ▁Sky ▁Model ▁is ▁high ▁for ▁both ▁clear ▁sk ies ▁and ▁cloud y ▁sk ies . ▁ ▁The ▁pattern ▁is ▁also ▁clearly ▁visible ▁in ▁small ▁visible ▁patch es ▁of ▁sky . ▁ ▁The ▁cel est ial ▁angle ▁of ▁polar ization ▁is ▁una ffect ed ▁by ▁clouds . ▁ ▁Pol ar ization ▁patterns ▁remain ▁consistent ▁even ▁when ▁the ▁sun ▁is ▁not ▁present ▁in ▁the ▁sky . ▁ ▁Tw il ight ▁patterns ▁are ▁produced ▁during ▁the ▁time ▁period ▁between ▁the ▁beginning ▁of ▁astronom ical ▁tw il