If you’ve ever looked up and thought you spotted a UFO hovering near the mountains, chances are you were actually seeing a lenticular clouds.
These smooth, lens-shaped clouds are some of the most eye-catching formations in the sky, and they form under very specific atmospheric conditions.
Lenticular cloud over the summit of Mount Washington (Mount Washington Observatory)
What are lenticular clouds?
Officially named Altocumulus standing lenticular clouds, these clouds are stationary. Unlike other clouds that drift with the wind, lenticular clouds stay in one place, even as strong winds move through them.
This is because the air forming them is constantly flowing through the cloud, condensing on one side and evaporating on the other.
How lenticular clouds form (WGME).
How do lenticular clouds form?
Lenticular clouds form when stable, moist air flows over mountains, creating standing waves in the atmosphere. As the air rises, it cools and condenses into a smooth, lens-shaped cloud. As the air sinks back down the other side of the mountain, it warms and evaporates, giving lenticular clouds their signature flying-saucer appearance.
Lenticular cloud formation (WGME).
Lenticular clouds are often a sign of strong winds aloft and a stable atmosphere.
Pilots pay close attention to them because mountain waves that create lenticular clouds can produce severe turbulence, even if the rest of the sky is clear.
Lenticular clouds (WGME).
These clouds are rare, but they appear most often during colder months. That’s because winds higher in the atmosphere tend to be stronger this time of year.
Lenticular Cloud in North Conway, New Hampshire (Caylin Parmenter).
Lenticular clouds will not form in flat areas, and are most commonly found over mountain ranges.