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 .
Nacreous clouds are a type of wave cloud composed of very small ( approximately 0.0004 in or 0.01 mm in diameter ) , similar-sized ice crystals or ice particles .
Surface microtopography , representation and tracing of nacreous layers of pteria penguin and blister pearl from sanya , hainan province , are studied by using interference microscope and environmental scanning electron microscope and atomic force microscope .
Among the numerous special effects available for the polymer industry , transparent effects such as pearlescent ( or nacreous ) , iridescent , sparkle or liquid metal effects are broadly used .
As the defense mechanism , the oyster production is called the nacreous layer one material result form nearby the intruder the lamination stack , the creation pearl .
由于防御机制,牡蛎生产所谓的珍珠层的结果形成一个物质的侵入附近的复合叠加,建立珍珠。
9 Nacreous clouds , or " mother of pearl " clouds , appear iridescent because of their ultrafine ice crystals , which form 10 to 15 miles up in the stratosphere .