Smooth motionless clouds are often mistaken for “unidentified flying objects.” However, they are not as mysterious as they might seem at first glance.
The Operational Land Imager (OLI) remote sensing instrument aboard the US satellite Landsat 8 captured images of soft-edged clouds hovering over the Eisenhower Ridge in Antarctica’s Transantarctic Mountains. Their range is limited in the north by the Priestley Glacier and in the south by the Reeves Glacier.
Clouds show signs of lenticular clouds that can form along the crests of leeward or mountain waves. They form when a fast moving wind is disrupted by a topographic barrier – in this case, the Eisenhower Ridge. The air is forced to rise above the mountains, causing waves of rising and falling air from the leeward side of the ridge. The rising streams are cooled and the water vapor condenses into clouds. Conversely, falling air leads to evaporation.
Added to their mystery is that this type of cloud appears to remain in place – sometimes for hours, challenging strong horizontal winds. In fact, clouds constantly gather around the crest of leeward waves and then dissipate a little further.