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Perlucidus Cloud Variety:Transparent By Small Gaps

Learn about the perlucidus cloud variety, including pictures and images of their various characteristics, how to identify them, and more.

Altocumulus stratiformis perlucidus (Ac str pe)
Altocumulus stratiformis perlucidus (Ac str pe)

Identifying the perluciduscloud variety

A variety of altocumulus or stratocumulus cloud containing gaps of blue sky

The ‘perlucidus’ cloud variety can be found amongst only two cloud types: altocumulus and stratocumulus. Translated from latin, meaning pellucid, the two types of perlucidus clouds are respectively abbreviated as ‘Ac la’ and ‘Sc la’. Perlucidus cloud formations can be easily identified as clouds with gaps in between cloud rolls or cloud heaps where you can see blue sky.

The perlucidus cloud variety is fairly common, especially amongst altocumulus clouds. Sometimes they take on an appearance that can be best described as cracks in a sidewalk. As a cloudspotter, if you see clouds that are perlucidus, you can work backwards to help you identify the cloud as altocumulus or stratocumulus.

They’re commonly found alongside the stratiformis cloud species. If they’re thin enough, they can also classified alongside the translucidus cloud variety. Perlucidus clouds are very rarely found alongside the opacus and lacunosus varieties.

Try not to confuse the cloud varieties translucidus and perlucidus. As noted above, perlucidus clouds can be translucidus, but the two varieties can be differentiated by translucidus clouds are transparent, where perlucidus clouds are identified through the cloudless gaps in between the cloud heaps. Also note that translucidus clouds can be found altostratus and stratus clouds in addition to altocumulus and altostratus.

Perlucidus and its cloud types

Perlucidus can modify each cloud type shown below. Compare how the same term appears across different levels and broader cloud forms.

Compare perlucidus with related cloud varieties

Use the defining shape, arrangement, associated cloud type, and full sky context before selecting the most appropriate term.

Perlucidus vs. translucidus

Perlucidus is defined by small gaps between cloud elements. Translucidus is defined by light passing through the cloud material itself.

Illustration of perlucidus clouds
Perlucidus
Illustration of translucidus clouds
Translucidus

Perlucidus vs. lacunosus

Perlucidus shows small gaps between cloud elements. Lacunosus has more organized, rounded holes with frayed edges and a net-like appearance.

Illustration of perlucidus clouds
Perlucidus
Illustration of lacunosus clouds
Lacunosus
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