Lingering up on high in an almost timeless stasis, cirrus clouds are some of the most visually arresting formations in the sky.
Delicate, diaphanous, and wholly dissimilar to their cousin clouds, they almost appear spread on the blue altitudes with a butter knife, instilling serenity in the heart of anyone lucky enough to catch a glimpse.
… but that’s enough waxing lyrical; what does the science say about cirrus formations?
Cirrus Clouds Defined
Cirrus clouds are categorized as wispy, often lace-like high-altitude clouds composed of fine ice crystals, generally appearing before a transition in weather.
Their distinct appearance and behavior – similar to that of an ink droplet in water – can be chalked down to their icy composition, a structural aspect that separates them from the other nine cloud forms primarily made up of water droplets.
The ice in its cloud DNA also gives the cirrus special photic abilities, as the interplay of light and crystal can create striking sky-strung phenomena, such as sun dogs and cloud iridescence.
In their most recognizable state, cirrus clouds are fibrous and silken, rife with calligraphy-esque curls and flicks, sometimes with spidery or wishbone intersections, but this isn’t their only form.
They can also gather together into a cottony clump known as cirrus spissatus, or tangle into cirrus intortus, a subform that can become so woven as to form a fine blanket over a large stretch of sky.
Part of the cirrus cloud’s majesty is its altitude, so when viewed close to the horizon line, they rarely look as impressive, to the point that you may not identify them as cirri at all.
Another unique thing about cirrus clouds is that they can be man-made. You know the condensation trails of aircraft that linger in the troposphere long after the plane is out of sight? Well, those are technically a type of cirrus known as cirrus homogenitus.
Cirrus Clouds: The Essential Facts
- Étage (Cloud Level): High – the farthest reaches of the troposphere
- Altitude: Between 4 and 15 km (16,000–49,000 ft) – higher elevations in the tropics and lower elevations over polar regions.
- Etymology: “Cirrus” is derived from Latin cirro which translates as “curl”
- Abbreviated Name: Ci
What Color Are Cirrus Clouds?
Cirrus clouds are usually light gray to pure white but will sometimes appear iridescent in the right light.
Potential For Precipitation
Do cirri clouds mean rain? Technically, no, but it’s a little more complicated than that. Made up of ice crystals, cirri don’t have any liquid water to spill themselves, but they do often foreshadow the coming of rain or storms.
Sky Cover Conditions
Cirri are most common when it’s sunny as there are fewer opaque clouds in the sky to eclipse them, and the light highlights their ice crystals.
Cirrus clouds are incredibly common and can be seen year-round.
Cirrus Cloud Subspecies
“Cirrus” is actually a cloud family of five related yet distinct species.
This species is distinguished by a rising bunny tale/turret shape at one end of the formation.
Cirrus fibratus are the classic hair-like streaks that first come to mind when you think of this type of cloud.
Similar to cirrus castellanus, cirrus floccus can be identified by a ragged tuft at the periphery of the formation; however, in this instance, it won’t rise into a turret.
This is the densely packed cirrus we discussed earlier on.
Cirrus uncinus is relatively comma-shaped, but with multiple tails. Perhaps a more suitable description would be a tiger scratch in the sky.
Variations Of Cirrus
On top of the five aforementioned species, cirri come in the following four varieties.
Similar cirrus clouds layered.
Bands stretching in parallel.
Resembling a spin and ribs, hence “vertebratus”.
Supplementary Features Of Cirrus Clouds
You may also catch one of these two supplementary features hanging around cirrus clouds.
Wave-like additions known as Kelvin-Helmholtz waves.
A soft cloud clump with an udder-like periphery.
There are no cirrus accessory clouds to speak of, but they do share a link with the following two cloud types.
Man-made clouds such as the streaking caused by aircraft.
A mutated form of the previous man-made cloud type. Multiple fine fish-bone-like protrusions bleed from the main streak.
Similar Cloud Formations
Don’t be mistaken; the following two cloud types do not strictly belong beneath the cirrus umbrella.
A hybrid form composed of cirrus and cumulus elements, the cirrocumulus cloud inhabits the same altitude as cirri but is decidedly puffier, populated with cloudlets that vaguely resemble grains of rice.
The cirrostratus can also be found at cirrus altitude, but you can tell them apart by the formless veiling of cirrostratus as opposed to the more intricate and well-defined cirrus. In other words, the cirrostratus will be quite simple and bulbous, while the cirrus will be more complex.
Cirri are truly awe-inspiring cloud formations, and now you know a little more about them, you can make your own observations and learn even more — Happy cloud watching!
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