Nacreous

Nacreous are among the rarest of clouds, they are mostly visible two hours after sunset or before dawn when they shine brightly with vivid and slowly shifting iridescent colors.

Photo Op The Year in Pictures 2008

Nacreous are among the rarest of clouds, they are mostly visible two hours after sunset or before dawn when they shine brightly with vivid and slowly shifting iridescent colors.

Archive 2008-11-01 The Year in Pictures 2008

Nacreous clouds are the most dramatic manifestation of polar stratospheric clouds, but they are rare in the Arctic, northern polar regions are warmer than Antarctica.

Terra Incognita Wheeler, Sarah 1996

Nacreous clouds, typically, are visible in September.

Terra Incognita Wheeler, Sarah 1996

Nacreous: Translucent, greyish-white, with pearly lustre.

The Elements of Bacteriological Technique A Laboratory Guide for Medical, Dental, and Technical Students. Second Edition Rewritten and Enlarged.

Nacreous: pearly: resembling mother of pearl: = margaritaceous.

Explanation of Terms Used in Entomology John. B. Smith

Nacreous shell has attracted materials scientists already long, due to its lightweight but strong structure.

PhysOrg.com - latest science and technology news stories PhysOrg Team 2010

Nacreous or "mother of pearl" clouds are made of microscopic ice crystals floating in the stratosphere 9 to 16 miles high.

My[confined]Space 2009

Nacreous clouds are supposed to be rare, yet sky watchers in Scandinavia has spotted them frequently during the past two weeks.

My[confined]Space 2009