APOD: Asperitas Clouds Over New Zealand (2018 Aug 19)

[APOD Robot]

Asperitas Clouds Over New Zealand

Explanation: What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Formally recognized as a distinct cloud type only last year, Asperitas clouds can be stunning in appearance, unusual in occurrence, and are relatively unstudied. Whereas most low cloud decks are flat bottomed, asperitas clouds appear to have significant vertical structure underneath. Speculation therefore holds that asperitas clouds might be related to lenticular clouds that form near mountains, or mammatus clouds associated with thunderstorms, or perhaps a foehn wind -- a type of dry downward wind that flows off mountains. Such a wind called the Canterbury arch streams toward the east coast of New Zealand's South Island. The featured image, taken above Hanmer Springs in Canterbury, New Zealand, in 2005, shows great detail partly because sunlight illuminates the undulating clouds from the side.

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[GwydionM]

To me, they looked rather like the swirls seen on Jupiter - though of course those are enormously larger.

Has anyone explored this?

I'm a retired computer analyst with a lifelong interest in science, including astronomy. You can find me at https://gwydionmadawc.com/.

[Whiskybreath]

I saw such clouds near Mt Kilimanjaro when I lived there, together with another peculiar phenomenon; a low ceiling of dark cloud arranged in hexagonal cells, which appeared to 'boil'. This took place on the plain between Kilimanjaro and Mt Meru, which with the Lelatema range of hills to the South, is actually a vast bowl.

[neufer]

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Asperitas is a genus of air-breathing land snails,
terrestrial pulmonate gastropod mollusks in the family Dyakiidae.

Asparagus From Tip to Butt

[De58te]

Interesting. The APOD robot calls them asperitas clouds, yet the two links to USA Today calls them asperatus clouds. Even the Wiki link calls them asperitas in the first paragraph, yet calls them asperatus in the remaining article.

[neufer]

Click to play embedded YouTube video.

Interesting. The APOD robot calls them asperitas clouds, yet the two links to USA Today calls them asperatus clouds. Even the Wiki link calls them asperitas in the first paragraph, yet calls them asperatus in the remaining article.

"Asperitas (formerly known as Undulatus asperatus) "

[Boomer12k]

Fascinating Clouds...

Instead of a consistent layer of clouds...globbed moisture areas...a denser area of moisture, pushes out and down, in and maybe even above the layer...held as a kind of "cloud bubble"???

Interesting stuff
:---[===] *

[JoelB]

Appearance MAY have be an effect from very cold air diving from above the warmer thermal cloud layer into some sort of weakness in the layers below.

[bmesser]

Looks like some old fashioned contorted altocumulus lenticularis to me.

[pausch]

"Formally recognized as a distinct cloud type only last year" -- asperitas is not a cloud type (species) but a supplementary feature. Like mammatus clouds. The asperitas supplementay feature is usually associated with stratocumulus or altocumulus clouds. I would consider the clouds in the APOD image to be stratocumulus asperitas.
https://en.wikipedia.org/wiki/List_of_c ... y_features

[neufer]

Appearance MAY have be an effect from very cold air diving from above the warmer thermal cloud layer into some sort of weakness in the layers below.

<<By studying the weather records and using a computer model to simulate the cloud, Graeme Anderson, an MSc student at the Department of Meteorology, Reading University, found evidence that asperatus is formed in the sort of conditions that produce mamma clouds (also known as mammatus), but when the winds up at the cloud level cause [mamma clouds] to be sheared into wavelike forms known as undulatus.>>

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<<Mammatus (mamma or mammatocumulus), meaning "mammary cloud", is a cellular pattern of pouches hanging underneath the base of a cloud, typically cumulonimbus rainclouds, although they may be attached to other classes of parent clouds. The name mammatus is derived from the Latin mamma (meaning "udder" or "breast"). According to the WMO International Cloud Atlas, mamma is a cloud supplementary feature rather than a genus, species or variety of cloud. [Mamma clouds] are formed by cold air sinking down to form the pockets contrary to the puffs of clouds rising through the convection of warm air. These formations were first described in 1894 by William Clement Ley. This plenitude of proposed formation mechanisms shows, if nothing else, that the mammatus cloud is generally poorly understood.>>