Photos of yesterday’s patterns
I could literally hear the cameras clicking all over Catalina and Oro Valley as these patterns showed up, moving in from the southwest as the increasing numbers of cloud-centric folk lost control of themselves. Reflecting that general loss of control, which affected yours truly, too many photos will be posted here. Below holey clouds with icy centers, but not ones caused by aircraft:
And look closely at the fine patterns, lines and granulations in these shots! Truly mesmerizing.
But what’s missing in this photo above? There was no iridescence seen around the sun where we normally look for it suggesting that those Cirrocumulus clouds nearest the sun were composed of ice crystals, and not tiny droplets. Iridescence is rarely seen next to the sun due to ice crystals because they are usually the result of the freezing of existing droplets, that then grow rapidly as ice particles to sizes too large to produce diffraction phenomenon close to the sun. Where’s my Lear jet, so’s I can confirm these speculations?!! I would very much like to have one on “stand by”, in case I think of something. Below, a wonderful example of no iridescence even though newly formed clouds are by the sun:
A jet runs through it
Or so I thought. In this chapter of cloud-maven.com, we inspect the photos of a commercial jet flying at or near the level of these clouds and determine what happened. I was quite excited to see this happen because we would now determine whether there were any liquid droplets in what to the eye of the amateur cloud watching person would be a liquid droplet Altocumulus clouds. Here the size of the elements are just a bit too large to lump it into the Cirrocumulus category, if you care. So, with heart pounding, took this sequence of photos:
Let is go zooming:
By the way, if you caught it, there were a couple of standard, aircraft-produced, “hole punch” clouds at the very upwind, formative portion of this patch of clouds before it got here. These photos pretty much prove that the Cc at the formative end at that time was composed of highly supercooled droplets and that the passage of an aircraft produced ice, that caused a fall out hole.
The End–quite enough, eh?
8 thoughts on “More patterns galore, but with natural holes in them that made for an extra fascinating day!”
Thanks, Andy, for taking time to comment out of your busy schedule!
Beautiful cloud shots, Art! I only wish I could see something like that in the near future.
I hope you do, too, Roland. They were memorable.
I haven’t checked in here in awhile and see that I’ve been missing some interesting stuff.
About the ‘holey’ clouds at the top, if the cloud was all ice, then what caused the holes? I seemed to have missed something.
Also, what is the Banner University of Arizona? Some slang name for UofA in Tucson, or a new campus or university group?
Indeed, that was the best photo of a cloud without iridescence that I’ve ever seen. Funny stuff, thanks Art-
I don’t think those Cirrocu at the top of the first two photos were all ice. Will have to go back and look if that was what I said.
I think they were on the verge of homogeneous nucleation due to the temperature and here and there, ice took off. I have seen clouds like that, and even videoed them with clean holes, trying to see if I could see how they formed. I couldn’t because they were moving to fast for a stationary video. HOWEVER, in a case of similar holes in a lower lenticular layer at the top of the boundary layer, a high one (!), the holes were produced by dry thermals reaching the bottom of the smooth lenticular clouds and this could be seen in a video. There were clear holes in the layer you’re commenting on, too, and they would have been too high for that kind of thing, of course. So, I have to guess–hand wave–that it was due to downward pokes of dry air from aloft. However, one observer saw itty bitty holes, pin holes, that grew some in that layer that seemed too small for ordinary dry blobs possibly, or not, to conclude on a definite note. This is why I need my own personal Lear jet, so’s I can answer questions like this even MORE definitively!
PS: Will send an e-mail to get the scoop on what you’re up to, Dr. Jon Nelson, the real “ice man” (http://www.storyofsnow.com/blog1.php) What a nice blog!
So, the holes may have two causes, 1) dry air descending from above, and 2) nucleation of ice?
The cases with some cloud in the middle of the hole look like 2, but the empty holes may be 1)?
I’ve seen cases with the cloud patch in the center and concluded 2) (based perhaps on info I read from your cloud poster!). But have never seen the empty holes. I’ll be watching more!
One thing I wonder about the lack of iridescence – could it be that the droplet population in some of those cases is broad, so that the variously colored bands overlap, producing white?
This might not make much sense for the droplet microphysics expert, but I’m no expert there.
Thanks for the plug of my snow blog. I wish I could post more often.
Hi, again, Jon,
I think you’re possibilities have to be correct, in the one case ice has erupted in cloudlets already near the homogeneous nucleation point, and there is likely some little bit of turbulence punching holes here and there. This is the first time I saw ice centers in Cc with holes like this. Several years ago there was almost the exact copy of these clouds, but no obvious ice, just little holes, from almost pin holes to broader ones like those shown here.
At one point, the holes were in a line, and I wondered in the downward holes weren’t produced by a passing jet’s wingtip vortices, one flying in very dry air since there was no contrail. But, that was a pretty wild guess!
The lack of iridescence cloud shot looked like cloudlets that were composed of ice to me, but a subtle version in which the cloudlets can LOOK an awful lot like they’re composed of liquid droplets. Can a broader droplet spectrum exist at temperatures lower than -30° C? I think the answer is yes if there are very few CCN, so what you’re suggesting is possible, though I would tend toward ice being present (and particles a bit too large) as the best explanation of the lack of iridescence.
Thanks, Jon, for your thoughtful commentary.
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