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Lenticular Clouds: The Rare Cloud Formations Look Like Objects From Another World

Lenticular clouds (Altocumulus lenticularis) are stationary lens-shaped clouds that form in the troposphere, normally in perpendicular alignment to the wind direction.

Clouds associated with mountain waves

If you’re lucky, you may have already seen the stunning meteorological phenomenon we’re about to explore today. Yet, while lenticular clouds are a rare spectacle for many people, if the conditions are right, it’s not impossible to catch sight of them – and better still, to capture them on camera! In fact, their appearance is so distinctive that to human eyes they are often mistaken as close encounters of the third kind – and looking at these 20 amazing images, we can see why!

Mechanical turbulence
"As air flows along the surface of the Earth, it encounters obstructions. These are man-made objects, such as buildings and bridges, and natural features, like hills, valleys, and mountains. All of them disrupt the flow of air into eddies. The strength of the eddies depends on the size of the object and the speed of the wind. It results in turbulence we classify as ‘mechanical’ because it is formed through the “mechanical disruption of the ambient wind flow".

Mechanical turbulence

"The degree of mechanical turbulence depends on wind speed and roughness of the obstructions. The higher the speed and/or the rougher the surface, the greater is the turbulence. As unstable air crosses the barrier, it spills down the leeward slope often as a violent downdraft. Sometimes the downward speed exceeds the maximum climb rate for your aircraft and may drive the craft into the mountainside. In the process of crossing the mountains, mixing reduces the instability to some extent."

Mountain waves
Mountain waves

"When stable air crosses a mountain barrier…air flowing up the windward side is relatively smooth. Wind flow across the barrier is laminar – that is, it tends to flow in layers. The barrier may set up waves in these layers much as waves develop on a disturbed water surface. The waves remain nearly stationary while the wind blows rapidly through them. The wave pattern is a ‘standing’ or ‘mountain’ wave, so named because it remains essentially stationary and is associated with the mountain."

A menacing lenticular cloud ‘tower’ spotted close to El Calafate in Patagonia, Argentina
A menacing lenticular cloud ‘tower’ spotted close to El Calafate in Patagonia, Argentina

But how do lenticular clouds like those of the altocumulus variety form? Well, it’s all about the wind – the direction in which it is blowing and what lies in its path. Basically, comparatively stable, fast-moving air is pushed upwards upon meeting a topographic barrier (like a mountain) that is positioned perpendicular to the movement of the upper-level winds. This is why lenticular clouds are more often spotted close to great mountain ranges like the Himalayas, Andes or Rockies

Lenticular cloud caps this mountain in Oregon.
Lenticular cloud caps this mountain in Oregon.

Where stable moist air flows over a mountain or a range of mountains, a series of large-scale standing waves may form on the downwind side. Lenticular clouds sometimes form at the crests of these waves. Under certain conditions, long strings of lenticular clouds can form, creating a formation known as a wave cloud.

These beautiful lenticular clouds over Mount Hotaka in Japan almost look like hot air balloons!
These beautiful lenticular clouds over Mount Hotaka in Japan almost look like hot air balloons!

The mountain barrier obstructs the upward-streaming winds, and this in turn produces a ‘gravity wave’ (also known as a standing wave) downwind from the mountain. Altocumulus standing lenticularis clouds will form when there is enough moisture in the air above the summit. This is the reason why lenticular clouds are often photographed enshrouding mountaintops (this, and the fact that they look so awesome that shutterbugs can’t get enough of them!)

Lenticular cloud near Pahala, Hawaii at dusk.
Lenticular cloud near Pahala, Hawaii at dusk

Source: Environmental graffiti
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Lenticular Clouds: The Rare Cloud Formations Look Like Objects From Another World Lenticular Clouds: The Rare Cloud Formations Look Like Objects From Another World Reviewed by Eli Snow on 3:04 AM Rating: 5

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