|Iridescent Clouds ~ Anders Falk Jensen imaged this dramatic scene while flying between huge thunder clouds over Brazil. The filmy iridescent clouds are likely pileus formed when moist air layers are pushed upwards by growing cumulus below. At first sight they might be mistaken for rare nacreous cloud but they are at too low an altitude and nacreous clouds do not occur at Brazil’s latitudes. ©Anders Falk Jensen, shown with permission|
Back to the troposphere ~ Another image over Brazil by Anders Falk Jensen.
|Nacreous Clouds ~ For comparison, an image from a NASA research aircraft taken by Paul Newman of Goddard Space Flight Centre. The aircraft is higher and yet the intensely bright wavelike nacreous clouds are higher still (9-16 miles in the stratosphere). Nacreous clouds need below average stratospheric temperatures (<-85C) and are restricted to high latitude winters. ©Paul A Newman/NASA, shown with permission|