Lenticular clouds (Altocumulus lenticularis in Latin) is a lentil-shaped type of cloud from which it got its name. These are strange and unnatural-looking clouds that are primarily formed in the troposphere. Lenticular clouds are usually formed in an alignment perpendicular to the wind direction.
They primarily develop among the crests and valleys of hills or mountains. The clouds are linked with atmospheric waves that form when the flow of moist air is forced up, atop, and halfway down the top of a mountain. The moist air then cools, which causes it to condense into a disk-shaped cloud.
The cloud’s appearance is often compared to a lens or saucers since these luminous iridescent clouds formed in the lower stratosphere occasionally have lenticular shapes. Lenticular clouds are sometimes called “UFO clouds” because they look like the flying saucers we see in science fiction.
Some even believe that real lenticular clouds’ sightings are the most frequent explanations for UFO sightings. These saucer-shaped clouds are most likely to become more prominent during the autumn and winter seasons.
How Do Lenticular Clouds Form?
Air travels along the surface of the Earth, and more often than not, it encounters obstructions. These obstructions include natural features of the Earth-like hills and mountains and artificial structures like buildings and other towering structures. These obstructions cause airflow to disrupt into “eddies,” which are the turbulence areas influenced by them.
Lenticular clouds are formed when moist, stable air blows across an end, setting up a succession of large standing waves in the air downwind. It’s like the formation of ripples in a river when water flows over an obstacle. The wave’s rising motion will cause the water vapor to condense, but it only happens if the temperature at the wave crest drops below the local dew point.
This forms the unique formation known as “wave clouds” or lenticular clouds. These clouds can produce a solid upward wind current, sometimes enough for water vapor to condense and start making precipitation.
Lenticular clouds have been mistakenly identified as UFOs since many of them are in the shape of a flying saucer with a smooth, “saucer-like” shape and a characteristic lens. Since these clouds usually do not form over flat terrain, many people may not have seen one or know its existence. The edge of lenticular clouds sometimes has bright colors or iridescence.
Frequently, lenticular clouds resemble a spaceship drifting in a nearby mountain’s summit, and there are also times when multiple clouds pile on top of each other, very much like a stack of pancakes.
Not only are lenticular clouds unique, but they also behave differently than other clouds. Lenticular clouds do not move with the wind flow and can remain in one location for hours as they reform over and over again in the mountain wave crest.
A mountain located southeast of Seattle named Mount Rainier is a magnet for lenticular clouds. There has been a multitude of news stories about the lenticulars hovering over the mountain. As to why the mountain is such a hotspot for lenticular sightings? It might be due to the wind and moisture coming off the Pacific Ocean that is forced to rise over the region’s tallest peak, and since lenticular clouds form before a storm arrives, thick clouds that obscure lenticular clouds from view are yet to be present.
What Weather Do You Associate With Lenticular Clouds?
The presence of lenticular clouds is a clear sign of mountain waves in the air. Although, these waves may exist even when no clouds are formed and exist beyond the clouds.
However, these clouds’ presence on land can result in extreme turbulence of winds in one area and with still air located only a couple of hundred meters away. Lenticular clouds often indicate a significant instability in that layer of the atmosphere, making it a “rough ride” for planes.
If you have sightings of Lenticular clouds, you can probably detect that the air above is very turbulent. They may look pretty, but these clouds are “mean.”
What Are the Different Categories of Lenticular Clouds?
Lenticular clouds are divided into three main types. These are:
- Altocumulus Standing Lenticular (ACSL)
- Stratocumulus Standing Lenticular (SCSL)
- Cirrocumulus Standing Lenticular (CCSL)
These different types are classified according to their altitude above the ground.
The lenticular cloud’s atmospheric waves bring about turbulence. This is the reason why pilots of powered aircraft avoid flying near them. It’s also because they’re a sign that rain or snow is on the way.
However, glider pilots diligently seek them out to climb the leading edge in the rising air mass. Its precise location is relatively easy to predict based on the cloud orientation. The “Wave lift” is often very smooth and robust, enabling gliders to rise to great altitudes and reach great distances.
Iridescent Lenticular Clouds
Cloud iridescence, also known as irisation, is a vivid optical phenomenon in the presence of the Moon and Sun in a cloud. The hues are similar to those found in oil on water and soap bubbles. It’s a form of a photometer.
These common phenomena are most typically encountered in lenticular cirrus clouds, appearing as bands parallel to the clouds’ edges. Iridescent clouds are a diffraction effect created by microscopic water droplets or ice crystals scattering light separately. Larger ice crystals do not produce iridescence; however, halos, a distinct phenomenon, can occur.
The cumulative effect of tiny ice crystals or water droplets similarly sized in regions of clouds is perceived as colors. Iridescent lenticular clouds’ colors are usually pastel, although they can be very bright or blended and look like mother-of-pearl. The effect can be challenging to notice when it appears near the Sun because the Sun’s glare obscures it.
This can be avoided by shading the Sun with one’s hand or concealing it behind a tree or structure. Other options are dark glasses, looking at the sky mirrored in a pool of water, or a convex mirror.
Iridescence is most visible in semi-transparent clouds or near cloud edges, with the brightest and most vivid iridescence occurring in newly forming clouds. The iridescence takes on the organized shape of a corona, a radiant circular disk around the Moon or Sun encircled by one or more colored rings, when the particles in a thin cloud are highly comparable in size over a vast area.