While animals like butterflies and peacocks produce iridescent color using layers of chitin , iridescence is almost unheard-of in plants .
像蝴蝶和孔雀这样的动物是利用甲壳素层产生的彩虹色,而在植物中彩虹色几乎是闻所未闻的。
Though they can be quite vivid , iridescent clouds usually aren 't nearly as bright as high altitude nacreous clouds , observed before sunrise or after sunset at polar latitudes .