This spectacular, multi-hued formation of so-called lenticular clouds was observed over Rocky Mountain National Park, near Estes Park, Colo. Professional photographer Richard H. Hahn snapped the magnificent view soon after sunset at 5:02 p.m. MST (7:02 EST) on Jan. 5.
Lenticular clouds form when waves of moist, fast-moving air are pushed upward by winds and ascend over high mountains. At the mountain's higher altitude, the moist air's water droplets cool and expand, and the water vapor condenses. When the air moves over the mountain top and descends to uniformly humid air conditions, lenticular clouds form.
These clouds are characterized by their smooth, symmetrical oval or round shapes, and because of this, are often referred to as "flying saucer" or "UFO" clouds.
"The significance of this particular atmospheric event was the dramatic shape and color of the cloud. It really did look like the 'mother ship' UFO," Hahn told LiveScience.com. "It was ominous and breathtaking."
Lenticular clouds, like the ones seen in Antarctica (shown here), are so smooth and round that they're sometimes mistaken for UFOs. Like some other cloud formations, including wave clouds, lenticular clouds form because of the vagaries of winds around mountain peaks.
Approaching thunderstorm with lead gust front. Rain-cooled air from the storm moves out ahead of the storm. It ploughs under the warm moist air forming a flat "shelf cloud."
A localized rainstorm over the Arizona desert in 2008.
Globular mammatus clouds with radar in foreground. Often associated with thunderstorms and severe weather.
Globular mammatus clouds. These clouds are often associated with thunderstorms and severe weather.
Clouds over Estrange, Sweden in January, 2011.
Thick wave clouds are captured over Mt. Pisgah.
Towering cumulus. Mammatus clouds visible under the "anvil".
Cumulonimbus (Thunderstorm) is shown forming in the background. Smaller low level "scud" appearing in foreground.
Lowering wall cloud under main thunderstorm updraft. Tornadoes will generally form in and ground the wall cloud.
Shown in the photograph is a wall cloud with tail cloud.
Supercell - often associated with violent weather.
Clouds hang low over a valley at Graubunden, Switzerland.
Captured in this photo is a blazing sunset seen near Throckmorton, Texas.
Stunning photo of a rainbow with a reflection over an Oklahoma Wheatfield.
This photo, taken in Russia, seems to show wispy dolphins jumping in the clouds.
A thunderstorm anvil at sunset.
Turbulent gust front clouds.
Dark clouds gather over a campsite on the Tibetan Plateau. The photographer wrote of this photo, "Everybody was watching the monsoonal arcus cloud rolling over the camp. Suddenly, the weather changed. Rubbish was flying around and three men were hanging at the kitchen tent to keep it in place. This fascinating view presented itself shortly before the place turned into chaos."
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.
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.
Cirrus clouds move across the sky.
Towering cumulus clouds as seen from above.
Above the stratocumulus looking at multi-layers of 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.
Stratospheric clouds above the Arctic.
The sky appears upside-down in Lake Bohinj, Slovenia.
