ith ▁direction ▁and ▁the ▁solar ▁direction . ▁This ▁is ▁thus ▁heavily ▁dependent ▁on ▁the ▁changing ▁solar ▁direction ▁as ▁the ▁sun ▁moves ▁across ▁the ▁sky . ▁ ▁The ▁middle ▁one ▁represents ▁the ▁angle ▁at ▁the ▁sun ▁between ▁the ▁z en ith ▁direction ▁and ▁the ▁pointing . ▁Again ▁this ▁is ▁heavily ▁dependent ▁on ▁the ▁changing ▁pointing . ▁This ▁is ▁symmet rical ▁between ▁the ▁North ▁and ▁South ▁hem is pher es . ▁The ▁right ▁one ▁represents ▁the ▁angle ▁at ▁the ▁z en ith ▁between ▁the ▁solar ▁direction ▁and ▁the ▁pointing . ▁It ▁thus ▁rot ates ▁around ▁the ▁cel est ial ▁sphere . ▁ ▁D eg ree ▁of ▁polar ization ▁The ▁Ray le igh ▁sky ▁model ▁predict s ▁the ▁degree ▁of ▁sky ▁polar ization ▁as : ▁ ▁As ▁a ▁simple ▁example ▁one ▁can ▁map ▁the ▁degree ▁of ▁polar ization ▁on ▁the ▁horizon . ▁ ▁As ▁seen ▁in ▁the ▁figure ▁to ▁the ▁right ▁it ▁is ▁high ▁in ▁the ▁North ▁( 0 ° ▁and ▁ 3 6 0 ° ) ▁and ▁the ▁South ▁( 1 8 0 ° ). ▁ ▁It ▁then ▁res emb les ▁a ▁cos ine ▁function ▁and ▁decre ases ▁toward ▁the ▁East ▁and ▁West ▁reaching ▁zero ▁at ▁these ▁cardinal ▁directions . ▁ ▁The ▁degree ▁of ▁polar ization ▁is ▁easily ▁understood ▁when ▁mapped ▁onto ▁an ▁alt itude - az im uth ▁grid ▁as ▁shown ▁below . ▁ ▁As ▁the ▁sun ▁sets ▁due ▁West , ▁the ▁maximum ▁degree ▁of ▁polar ization ▁can ▁be ▁seen ▁in ▁the ▁North - Z en ith - S outh ▁plane . ▁ ▁Al