Strange sunset brew of clouds and color; but was it natural?

Cutting to the chase: I don’t think so.

Yesterday, after an ordinary beginning,, finished in a spectacular, if likely artificial way. Let us work our way through yesterday’s cloudulations:

7:39 AM. I thought this was a cute display by this little cloud, making its own little shadow rays as the sun made its way up from behind the Catlinas.

7:40 AM. But what kind of cloud is it? It, to these eyes, is all ice, but LOOKS like an Altocumulus cloud. But those clouds are all or mostly comprised of liquid drops. And you can see that this little guy is well BELOW a higher layer of ice cloud, we might call CIrrostratus, or a thin Altostratus. Oh, well, let’s move on to something explicable….

7:41 AM. Hmmmm. Quite a linear virga feature over there. There are THREE cloud layers evident here, a thin Altocumulus layer, that dark cloud on the left, and patch of what I could call, Altostratus extending from the left corner to the right corner, and a thin layer of CIrrostratus on top.

7:41 AM. Let’s go zooming and check it out…. Though we don’t know for SURE, anytime you see this kind of linear virga anomaly, you should be smelling aircraft exhaust. Now, when you think about our fabulous sunset last evening and what that looked like, take a closer look at this photo.

Later that morning…..

10:53 AM. 10:47 AM. It was nice to see low clouds topping Sam Ridge, the lower boundary layer air (where convection takes place) moist for a change. — 10:53 AM. It was nice to see low clouds topping Sam Ridge at dawn yesterday, the lower boundary layer air (where convection takes place) moist for a change. Later they devolved into small Cumulus (humilis and fractus).

3:29 PM. A day with mostly ice clouds on top of Catalina, but here, off in the distance below the Cirrostratus, is an invading layer of Altostratus and Altocumulus that will set the stage for sunset glory later. You may be able to detect a faint halo, upper center. By the way, Cirrostratus typically deepens downward to morph into Altostratus, usually an ice cloud, too, but is deep enough to produce gray shading, and when its really thick or has embedded droplet clouds, hides the sun.

4:02 PM. Yep, moving right in. This is a very complex scene. There’s aCirrostratus ice layer. upper right quadrant , on top of everything. Below that, what appears here as a distinctly lower separate layer, a mix of Altocumulus (those dark cloudlets composed all or mostly of liquid droplets) and Altostratus (mostly or all ice, the smudgy more diffuse dark areas) . We can never forget that Altocumulus can morph into Altostratus, which would then be called, “Altostratus altocumulotransmutatus.” Tell that to your friends! (Well, maybe not.)

4:15 PM. Caught this bumpy aircraft contrail at CIrrus levels. Look how how the exhaust and water vapor that formed this, though output from an aircraft in a steady state, how the wing tip vorices (apparently) get entertwined at regular intervals with more exhaust and water vapor in those blobs.

But let’s go zooming up to flight level and take a closer look for a second:

A mammatus (or as the ladies like to call it) testicularis contrail. Almost certainly this is due to combining wing tip vortices. Many aircraft now have devices to defeat wing tip vortices, phenomenon that reduce flight efficiency. — A “mammatus” (or as the ladies like to call it. a testicularis contrail (the resemblances are pretty good). Almost certainly this is due to combining wing tip vortices. Many aircraft now have devices to defeat wing tip vortices, phenomenon that reduce flight efficiency. In both cases above, the ice particles have not grown enough to produce fallstreaks. These images tell us that SOME aircraft that produce ice in supercooled Altocumulus clouds, as we in Catalina have seen lately, are likely to have bunches of ice trails rather than a continuum if produced in a uniform cloud, anyway.

Now, where was I? Got mammatus on my mind again. I love mammatus so much… Oh, yeah, that sunset yesterday…..

5:13 PM. Ran out to check sunset status, and saw this feature advancing rapidly toward Catalina.

5:18 PM. Zoomed view; getting close to passing overhead. You might be able to notice that these pretty regularly spaced trails are BELOW the Altocumulus clouds, and there's a clearing that's been produced. All evidence of an artificial production of these trails. But belng below the Altocu, you might also have started to wonder whether the setting sun would light them up.... — 5:18 PM. Zoomed view; getting close to passing overhead. You might be able to notice that these pretty regularly spaced trails are BELOW the Altocumulus clouds, and there’s a clearing that’s been produced. All evidence of an artificial production of these trails. But belng below the Altocu, you might also have started to wonder whether the setting sun would light them up….

And the sun did its job….producing one of the greatest sunset scenes we’ve seen in a long time, even if phony (haha):

5:23 PM. Not zoomed, still a few minutes away to overhead passage. Very exciting to think this was going to pass overhead!

5:23 PM. Zoomed view. Again the pretty regular spacing is circumstantial evidence that nature didn't do it. — 5:23 PM. Zoomed view. Again the pretty regular spacing is circumstantial evidence that nature didn’t do it.

5:25 PM. Thank you sun! Looks pretty round again, which is good.

5:28 PM. Another view of the same thing.

5:28 PM. Our trails compared to the rest of the Altocumulus deck. Not much going on elsewhere in the way of natural virga.

5:29 PM. Taking WAY too many photos of the same thing. Out of control... Here I demonstrate that with another photo of the same thing. — 5:29 PM. Taking WAY too many photos of the same thing. Out of control… Here I demonstrate that with another photo of the same thing.

5:30 PM. After the trail hoopla, it was time to concentrate on the fabulous sunset taking place to the southwest of Catalina.

5:30 PM. Zooming in on interesting features; long trails, one with a clearing above it. Was it another aircraft-induced trail of ice and clearing above it? Probably. The trails to the left aren't as obviously produced by an aircraft, but I do think so anyway in this burst of objectivity. Recall that I have been trained as a "scientist" and don't care if I am wrong, but only about truth, as best as I can make it out. — 5:30 PM. Zooming in on interesting features; long trails, one with a clearing above it. Was it another aircraft-induced trail of ice and clearing above it? Probably. The trails to the left aren’t as obviously produced by an aircraft, but I do think so anyway in this burst of objectivity. Recall that I have been trained as a “scientist” and don’t care if I am wrong, but only about truth, as best as I can make it out.

Finally, let look at the TUS sounding for last evening, see how cold those Ac cloud were with the ice trail in them:

The Tucson rawinsonde balloon launch yesterday at about 3:30 PM. Goes up at about 1,000 feet a minute, so takes about 100 minutes to get to 100, 000 feet. They pop somewhere around that height or a little above. THought you like to know that. They have a little parachute to that when they come down, they don't bonk you too hard. Once in awhile people find them in remote areas downwind. — Results of the Tucson rawinsonde balloon launch yesterday at about 3:30 PM. Goes up at about 1,000 feet a minute, so takes about 100 minutes to get to 100, 000 feet. They pop somewhere around that height or a little above. THought you like to know that. They have a little parachute to that when they come down, they don’t bonk you too hard. Once in awhile people find them in remote areas downwind. You can send them back in to the NWS, too!

The astounding thing here, something that goes against everything I believe about clouds, is that it is indicated that the Altocumulus, lacking much natural ice, was at -30° C! Yikes! No wonder aircraft were producing ice trails and stuff yesterday afternoon.

You have to conclude there were almost no natural “ice nuclei” up there at, oh about 24,000 feet above sea level. This is not the first time for such an occurrence of liquid clouds sans much ice at low temperatures¹, but they are rare IME. This would never occur in a boundary layer cloud, that is, one where material from the earth’s surface is getting into the clouds, like the omnipresent dust, or biogenic ice nuclei.

The weather ahead

Some “fantasy” storms with rain in them for Catalina, are now seen on the model predictions beyond a week. Spaghetti is favoring this new development now. So, something to keep an eye on.

The view from here? Precip here is “in the bag” because going on subjective feelings, I really want to see a good rain here!

The End

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1The famous John Hallett said he saw an Altocumulus lenticularis sans ice at -35°C in a conference preprint! Rangno and Hobbs (1986) claimed to have detected droplets in Altocumulus like clouds at the top of a storm on the Washington coast at -44°C. Their claim, first published in a conference preprint, was later rejected by the J. Atmos. Sci.

Author: Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa. View all posts by Art Rangno

2 thoughts on “Strange sunset brew of clouds and color; but was it natural?”

Mike says:

December 13, 2016 at 9:57 am

It certainly has been a mid and high cloud lover’s paradise recently!
1. Art Rangno says:
  
  December 13, 2016 at 1:27 pm
  
  Thanks,Mike. There have been just some incredibly beautiful sights lately. Of course, would rather see three straight days of “Nimbostratus”…
  
  a

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