On a movie-sounding title theme again today, or this title could be the title of a bedtime story for kids, one that alludes to the Greek citizen bee keeper, Perlucidus, due to his early work in distributing hives, honey and honeycombs. Some cloud patterns resemble honeycombs, and so when Luke Howard decided to create a Latin system of names for clouds around 1802-03, he wanted to pay homage to Perlucidus1. Yesterday morning we had Altocumulus perlucidus and those clouds are discussed in detail below the lengthy “historic learning module” below.
——historic learning module————
Our Latin cloud naming system follows the tradition of Latin names first established in the hard sciences like botany and biology. After they did their naming thing, we weather folk decided, under leadership of Luke Howard, to “join the club”, to sound like the other scientists of the day when we were talkin’ clouds, that is, pretend to be on as solid a foundation as, say botanists, whom we likely envied, by creating a similar Latin naming system for clouds. That would show them!
Unfortunately, we really didn’t know what clouds had in them in those days, there were no aircraft measurements. Were they ice clouds or liquid droplet clouds, a mixture of both? And so the naming system that was developed came out a little fuzzy; flawed really. I guess “fuzzy” is appropriate for clouds. As the singer said, “I really don’t know clouds at all2.”
OK, after that “side lobe”…an example of fuzziness and flaws in our names: while Stratus and Altostratus have virtually the same name, and can look VERY similar on occasion, one (Stratus) is completely composed of droplets, and the other (Altostratus) is almost always completely composed of ice particles and snowflakes (aggregates of ice crystals, bunches locked together). No doubt Howard saw the visual resemblance from the ground, and may have thought they were composed of the same stuff.
Yet, from the name of Altostratus, you would think it is a droplet cloud like Stratus, but just located at a higher level (“alto” meaning “high” in Latin). Even our scientists confuse Altostratus in their peer-reviewed papers with something else because of this naming problem. A better name, since Altostratus is full of ice precipitation (unknown when Howard was making up his names, of course) would have been, “Altonimbostratus”. Nimbostratus, by definition, is a precipitating layer cloud, too.
Another problem in our naming system is that unlike in botany, where a redwood tree does not become a pine tree over time, clouds are always morphing into new forms.
And then we have to come up with silly expressions such as “Altostratus opacus cumulonimbomutatus”, what might pass for the remains of a Cumulonimbus cloud that has lost its base and only the heavy, higher level ice-cloud anvil (Altostratus) remains.
So, as Howard was attempting to follow the Latin scientific naming conventions of the day for clouds, up popped the descriptor, “perlucidus” for clouds patterned like a honeycomb in homage to Perlucidus1.
Two cloud genera (there are TEN3-I really like footnotes. They give a piece a really erudite feel even when its not), have the descriptor, perlucidus attached to them because they can attain a honeycomb pattern. These are Stratocumulus and Altocumulus, to repeat.
——-End of historic learning module———–
Yesterday we had some very cold Altocumulus perlucidus, some cloud elements shedding ice and disappearing because of it. The TUS morning sounding indicated these were in the range of -25 to -27 C. Here’s what these clouds looked like when they were still mainly composed of liquid droplets:
Strange Brew yesterday
There were also some very strange looking lower clouds as dry convection, associated with that little warming we had yesterday afternoon during this historic cold wave, bulged upward into a pretty moist laminar stable layer that resisted like heck being pushed up. When it was pushed up by that convection, which with greater moistness you would have seen as small Cumulus, instead you got slivers of clouds on top of where the Cumulus should have been. Those slivers of moist air that just reached the condensation level where droplets form in the air sliding over the top of the “invisible Cumulus.” The result, these odd forms shown below, resembling lenticular clouds with ragged bottoms in some cases:
The last photo of a band of Stratocumulus with a ton of ice in it is worthy of a comment. A few days ago, the models had this day having significant precip, precip that would have been snow, followed by the same vast clearing we had later yesterday. Imagine last night and this morning’s cooling air augmented by a snow cover! Yikes. Woulda been 5 degree colder than what is already a pipe bustin’ cold morning. Wouldn’t have had so much afternoon melting because the ground has been chilled for several days now.
Wishing you happy pipes this morning. They’re freezing up here, temperature now 22.x here.
BTW, the list of Arizona low record temperatures will grow substantially today, as if you didn’t know it.
The weather ahead? Warmer. Can it be otherwise?
The End
——-
1Shockingly, this part has been completely made up.
2She also said, “Ice cream castles in the air”, followed by, “Feathery canyons everywhere.” And finally, “Clouds got in my way.” (BTW, “Clouds got in my way”, too, as if you couldn’t tell!)
3The the ten are: Cumulus, Stratocumulus, Nimbostratus, Altostratus, Altocumulus, Stratus, Cirrus, Cirrostratus, Cirrocumulus, and the mighty most of the time, Cumulonimbus.
