FEATURE Lenticular Clouds aka Pancake Clouds

Lenticular clouds, which are sometimes referred to as 'pancake clouds', 'lennies', 'wave clouds' or 'UFO clouds', are characteristic of all mountain ranges and form in response to wind. To celebrate Pancake Tuesday (Shrove Tuesday), we have compiled a collection of some of the most stunning shots of Lenticular clouds. 

Wave Winds. Image Wikimedi
Lenticular clouds explanation: When strong winds blow over the mountains and force moist air up to cooler elevations, the moisture condenses. As the winds blow back down the other side of the mountains, the moisture re-vaporizes. The lenticular cloud is the condensed (visible) moisture under the wind stream; it doesn't drift like other clouds do because it's "trapped" in a pocket of relatively calm air just below the wind stream and just above warmer air below. The notion that the clouds are stationary is an optical effect. A lenticular cloud actually is forming on one end (front edge) and vanishing on the other, giving the appearance that it is in a fixed position. Lenticular clouds assume distinct shapes, generally resembling a disc (hence giving rise to a common name of "pancake clouds" or in a flat elongated shape stretching parallel to the mountain range.
Sharon Kearney sent this image of a Lenticular cloud over Wicklow in 2011
Sharon Kearney sent this image of a Lenticular cloud over Wicklow in 2011
The summit of Washington's Mount Rainier lies hidden beneath a stack of horizontally layered lenticular clouds. These clouds are formed by high winds blowing over rough terrain and are sometimes described as a "stack of pancakes."  Photo by: Photograph by Arco Images/Alamy; Credit: National Geographic Wall Paper
In this sunrise shot of Mount St. Helens, an active stratovolcano in the Pacific Northwest region of the United States, she appears to be blowing smoke rings. What forms the "smoke rings" is the air flowing over the mountain getting pushed up higher as it goes up and over the top. The moisture content and initial temperature are just right so that the moisture condenses from a vapor to small particles at the higher altitude. When the moving air moves past the peak and comes down again, the particles evaporate back to an invisible vapor. The two "pancakes" describe that there are two layers of air for which this is happening, thus making this impressive picture possible.
Pancake Clouds! Lenticular Clouds at Lago Pehoe, Torres del Paine, Patagonia
by Sergio R. Nuñez C at Flickr Creative Commons
Lenticular Cloud Over Hawaii  Credit:  Peter Michaud (Gemini Obs.)

TOP IMAGE: Lenticular cloud, seen between Haleb and Damascus, Syria.  
 Credit: Gianandrea Sandri/Roberto Cavallini