Islands in the Clouds
Clouds fill in mountain valleys in this 2008 aerial photo of northern Norway.
A roll cloud, associated with thunderstorm downdrafts and strange sea winds, tumbles across the sky off the coast of Brazil. Roll clouds are rare and harmless, though ominous-looking.
Altocumulus clouds in the sky.
Wispy Cirrus Clouds
Cirrus clouds move across the sky.
Clouds from Above
Towering cumulus clouds as seen from above.
On the Horizon
Above the stratocumulus looking at multi-layers of clouds.
Swallows and Storm Clouds
Swallows swoop below storm clouds, feeding on insects sucked skyward by updrafts.
These polar clouds, which are composed of frozen nitric acid and sulfuric acid, form when temperatures in the stratosphere fall below minus 108 F (minus 78 C). This is currently the case in vast sections of the Arctic. Chemical processes on the surface of the cloud particles transform the initially harmless chemicals from chlorofluorocarbons (CFCs) into aggressive ozone-depleting substances.
Clouds above the Arctic
Stratospheric clouds above the Arctic.
Mirroring the Sky
The sky appears upside-down in Lake Bohinj, Slovenia.