December 29, 2020
Smooth, fixed clouds are sometimes reported by the public as sightings of “unidentified flying objects.” But these clouds are not as mystical as they may initially appear.
On December 29, 2020, the Operational Land Imager (OLI) on Landsat 8 got these pictures of soft-edged clouds hovering over the Eisenhower Range of Antarctica’s Transantarctic Mountains. The variety is bounded to the north by Priestley Glacier and to the south by Reeves Glacier, both of which feed into the Nansen Ice Shelf on Terra Nova Bay.
The clouds have the trademarks of lenticular clouds that can form along the crests of mountain waves. Mountain waves form when quick moving wind is disrupted by a topographic barrier—in this case, the Eisenhower Range. Air is required to stream up and over the mountains, triggering waves of fluctuating air downwind of the variety. The increasing air cools and water vapor condenses into clouds. Conversely, falling air results in evaporation.
December 29, 2020. (Click image for larger, high-resolution view.)
Adding to their mystique, this cloud type appears to sit tight—in some cases for hours—defying the strong horizontal winds. In truth, the clouds are continuously developing around the crest of the wave and after that dissipating simply beyond.
In the United States, lenticular clouds are especially typical around the Rocky Mountains. They have actually been understood to take place over Antarctic mountains, too, however there are very few witnesses besides satellites. The white-on-white color of clouds over ice make the Antarctic variations more difficult to determine, even in satellite images. This natural-color image has actually been improved with infrared light to separate the white clouds from the white snow and ice listed below. The clouds likewise tossed rounded shadows on the landscape.
Still, a couple of individuals have actually seen lenticular clouds in Antarctica firsthand. Scientists dealing with NASA’s Operation Icebridge shot images of the phenomenon near Mount Discovery in 2013 and over Penny Ice Cap in 2015.
NASA Earth Observatory images by Joshua Stevens, utilizing Landsat information from the U.S. Geological Survey. Story by Kathryn Hansen with image analysis by Bastiaan Van Diedenhoven (NASA GISS/Columbia) and Jan Lenaerts (CU Boulder).
