Contrails – Page 2 – Cloud-maven

Pretty skies, but no castellanus (again)

Apparently the castellanus formations went over during the nighttime hours when we couldn’t see them…

But it was a fabulous day again of interesting high and middle cloud flecks anyway. Below, a reprise of yesterday’s clouds starting with that delicate patch of Cirrus passing over the Catalina Mountains with its tiny fibers of Cirrus uncinus embedded in it. I have also included two sinister crossing contrails. Who knows what evil lurks there? Perhaps they’re marking a target of some kind, or filling out a questionnaire with crosses instead of check marks. Oh, well.

Later, as the sheet clouds of various Cirrus, Cirrostratus, and even Altostratus with virga cleared off, we got into some scattered lenticulars, some of to the distant north, and with our usual friend downwind of the Catalinas, shown in the last two shots. It was able to hang on for several hours, right past sunset.

Again, for the whole day’s cloud excitement, a great place to go is to our very own U of AZ Wildcat time lapse movie. In the late afternoon of this movie, you can see some great Altocumulus lenticularis clouds hovering over and downwind of the Catalina Mountains, occasionally shooting upwind as the air moistens in the humped up airflow, and you can get a sense of how little the air is pushed up in lenticular clouds from this movie.

(Once again the caption function has quit in WP before I got to some of these. My apologies.)

The weather ahead

Gee, “dusty cold snap” is beginning to look more like “muddy waters” as the later model runs dip the jet stream farther and farther south over us on the 14th and 15th. Check this forecast of the precip hereabouts from the U of WA’s WRF-GFS model run from last night, showing a bit of rain HERE Saturday morning (colored areas of map). Sure hope so. Terribly cold air with this, too, for mid-April. Likely some low temperature records will be set in the State somewhere for this time of year with this.

The End.

SONY DSC — Tiny Cirrus uncinus, top center, Cirrocumulus top right with,oh, maybe Cirrus fibratus (has linear fibers) lower left.

Cloud quiz

While waiting for the rain, here are some of yesterday’s clouds. What were they?

Answers printed upside down at the bottom except that WordPress wouldn’t let me do that. It would be great if you turned your monitor upside down before you looked at the answers. One is a trick “question” because I took a picture of a cloud behind what appears to be an inanimate plant, focusing on the dead plant and so the cloud shown in the background is a little fuzzy to make it more difficult.

1. Cirrus spissatus, the only type of Cirrus allowed to have gray shading in the daytime. Note mammatus like feature in the center.

2. Contrail, unusually turreted one (hmmm, perhaps a part of some government conspiracy–hey, I am kidding the “chem-trail” people). There’s also a patch of Altocumulus floccus (or Altocumulus perlucidus would be OK, too) lower part of photo.

3. Cirrus castellanus-turreted Cirrus, don’t see that species too often because it is rarely so unstable at that height. “Unstable”-the temperature dropped a LOT as you went higher up there, more than usual.

4. Altocumulus floccus, horizon, upper right, Cirrus fibratus (pretty much delicate, straight fibers) middle.

5. Ocotillo (hahaha, its not a cloud!) ((Another example of the juvenile humor that the writer seems to be afflicted with). OK, it looks like mostly Cirrus castellanus in the distance.

What do these kinds of clouds tell us?

The atmosphere is moist, but only patchy moist, a frequent occurrence in desert areas because “patchy moist” at middle and high levels in the atmosphere is most often all you get on the southern periphery of the major storms to the north of Catalina in the cool part of the year.

The atmosphere over us, too, is only in ascent at an overall rate of maybe an inch or two a minute; a bit more inside the clouds, less outside the clouds. One way to KNOW how slight the air is rising, even in the clouds, is to observe that snow is falling out of some of them, tiny ice crystals, typically in the low hundreds of microns in maximum dimension (width of a few typical human hairs, which are about 100 microns in width.) Such tiny ice crystals have fallspeeds less than 0.3 meters per second, and so they wouldn’t be able to fallout with higher overall “slab” lifting, the rate of that the whole upper air is lifting at these cloud levels. Q. E. D.

What caused the lifting? When you see clouds scattered over such a vast area, they have to be due to a disturbance in the wind field, a trough is likely nearby, normally upstream.

I have not looked at maps lately, but will NOW to see if there is a bend in the winds (indicating a trough) at these heights (mostly Cirrus level). I don’t see one on the 300 millibar map (30,000 foot map) and so I am not going to show it. But anyway, I am right, I am sure. Now, I will begin a serious investigation to prove I am right. The models will know if there is lifting going on.

Yes! I have been saved in my assertion by my former employer, the University of Washington‘s MM5 model, and this was the first thing I looked at! Look at the predicted high “clouds” (those above 20,000 feet) over Arizona for yesterday at 2 PM AST! They can’t be there in the model unless it thinks the air is going up some. OK, past the exultation stage now. Moving on. Actually, the model predictions of Cirrus-ee clouds aren’t really that great, so it was quite a surprise to see this.

The End.

Complications in the sky

First of all, let me assure quesy readers that the jet leaving the contrail at left was not “flaming out” and about to crash as it traversed the sky at this time, as the staccato nature of the contrail at left might suggest. The staccato nature of the contrail is due to vagaries of humidity at flight level. Where it was quite dry, the contrail disappeared immediately behind the jet.

Its a little unusual to see such short segments like this, however.

What was really interesting and a bit inexplicable (again) except via a LOT of hand-waving is the crossing patterns seen in the clouds at left and in the next shot. Pretty darn remarkable. In the second photo, icy strands of cirrus (“fibratus”-the strands are straight in this variety) are seen running SE-NW, “whilst” above there are Cirrocumulus clouds with ripples and little cloudlets oriented from SW-NE! All of these clouds were moving rapidly from the SW.

Maybe its too complicated; we should forget about it and go to the movies. Well, the cloud movies…

Here is yesterday’s cloud movie presented by our own University of Arizona Wildcats. This will help.

First, if you take the time to load this time lapse movie, you will enjoy the tiny cloud “tumbleweed” that goes by at 12:02 PM. It really acts like one, as you will see! Its an entertaining sight, and one that illustrates the wind shear in the atmosphere yesterday.

And that’s what these remarkable crossing cloud configurations are about, changes in wind direction and speed with height, something we “met men” call “wind shear.”

Some of the clouds in the second photo passed within the viewing area of the U of A time lapse movie between 1:59 and 2:03 PM LST and you can just make out the cirrus clouds going by with their lower portions draining off to the right very slowly. In these blog photos, looking as those clouds approached from the SW, the trails appear to originate on the right and “drain” to the left, a mirror image.

Ice crystals in cirrus clouds often form in sudden appearing, tiny flocculent specs like the Cirrocumulus (Cc) clouds. In these photos, in these photos, the Cc clouds are above the icy cirrus clouds. What normally takes place is that the ice crystals grow and the largest ones fall out producing strands below the “head” of the cloud. The slower they fall, the more apt the fallstreak is to be drawn out over a long distance away from where the burst of ice formation took place, and if there is a sharp wind shear, the more angled and contorted the trail will look. Still, at right angles? The Tucson sounding for yesterday afternoon doesn’t reveal much wind shear in the moist layer where these clouds were forming, 23, 000 to 27,000 feet above sea level. On the other hand, balloon soundings would not show extremely sharp changes in wind direction/speed over very small height increments. So, it remains somewhat of a mystery. In view of the orientation along the jet airway upwind of this site that runs in the direction of the line cirrus in these photos, it is possible that these are contrail remnants. There jets that flew at low enough altitudes at times to glaciate some of the Cc-Altocumulus clouds and one short ice trail produced by an aircraft in them can been seen in the U of A movie at 2:43 PM.

Along with these interesting alignments were numerous optical phenomena yesterday, some of which I could not identify, such as in these three. I suspect the first one is something called a parhelic circle, if you happened to have seen this bright arc radiating away from the sun’s position. A bit more mysterious, at least to me, was the sudden brightening of the contrail segment above the Catalinas and the cirrus (uncinus) cloud, last two photos.

OK, enough. I tried my best to explain everything and I have failed.

The End.

Distracted jet pilots or WHAT?

Now here’s something I have NOT seen before, which is pretty hard to have happen after decades of photographing the sky. Here’s what I saw around 1:30 PM yesterday over Catalina. I took three photos starting at 1:27 PM, 1:31 PM and 1:37 PM. Here they are:

So, how to explain this odd “stitched” contrail? Well, we can start with a few “facts” and hypotheses concerned with the aircraft and its crew.

1) Of course, with today’s modern instrumentation, pilots no longer have to actually fly commercial jets anymore. They simply set their destination with their Tom-Tom GPSes; flight levels and so forth, and then go to sleep until near landing time when they have to wake up again to be sure the automated process is still working. Perhaps when I took these photos, the flight crew was napping and the plane was kind of zig-zagging around that bit, I’m sure to the amusement of the passengers, who probably needed some excitement anyway to distract them from their cramped quarters.

2) The pilots WERE flying the plane, but weren’t focusing on the task at hand, but were distracted while talking about stuff, maybe sports; perhaps recounting the great classic Superbowl game matching up two historic Rust Belt sports franchises, the Packers and the Steelers.

3) Since alcoholic beverages are available on flights, perhaps the pilots had some beer and while not necessarily really drunk, weren’t able to fly in a straight line.

Personally, I reject all of the above. They appear to be “strawmen”, the result of superficial thinking strictly for entertainment purposes rather than having any intellectual depth.

Now for the “WHAT” part.

4) There are rarely seen regular undulations in the higher cirrus clouds in these photos, amazing ones really. These reveal waves pretty much perpendicular to the wind direction. The flight track is along the wind (tail wind). These waves in the atmosphere are like gigantic ocean swells, usually occurring where there is an noticeable increase in the wind with height.

Could these waves have produced this stitched pattern? I am thinking “yes.” That aircraft was likely close to the bottom of those cirrus (undulatus) clouds, and was SURELY experiencing those atmospheric waves, and likely exciting the passengers who probably needed some excitement to distract them from their cramped quarters-worth repeating.

We can’t tell here whether the contrail is rising and falling as would be happening in the cirrus lines and between them, respectively, or whether there is a perturbation to the horizontal winds associated with those waves. A time lapse would be great here, and here’s one though it had some problems yesterday, from the University of Arizona’s Atmospheric Science Department. A part of the contrail moves into the time lapse frames at 1:30 PM over Tucson, and from this angle, looking toward the Catalina Mountains to the N-NE, it does give an impression that the contrail was rising and falling. Confidence is low here, though, in that description.

Here’s the last shot as this phenomenon and cirrus waves raced over the east horizon. This last one makes it appear that the horizontal winds fluctuated more than the vertical winds under these waves producing a zig-zag in the horizontal.

With all the wonderful cirrus clouds around yesterday after a long absence, we had another one of those memorable Arizona sunsets, see last photo.

The End.

More about holes-in-clouds while we’re waiting for the AZ rain in a few days

There have been a coupla comments on that aircraft effect in clouds blog of a coupla weeks ago and so I thought I would follow up with this sequence from the Atmos Sci Building rooftop at the University of Washington where I spent most of my time instead of at my desk.¹

Here is a rarely photographed sequence of the effect of an aircraft on a supercooled cloud. The first photo, right after a contrail-like feature was seen in these Altocumulus clouds.

APIPs REDO_078 — Look at what seems to be a dark contrail-like line in the middel of the photo. The Altocumulus (perlucidus) cloud layer, mostly comprised of supercooled liquid drops, is probably around -20 C, though I did not get a PIREP on this day for some reason.

In the minutes after this first photo, the aircraft trail seems to disappear as it widens and the shadow lessens. This stage is not shown because I didn’t realize what was going to happen until minutes later. This second stage is almost impossible to pick up visually because there are no ice trails yet, nor is the cloud opening up at this time. This “invisible” stage might last 5 minutes before you see the hair-like signs of a fallout of ice crystals.

APIPs REDO_081 — This second photo is about ten minutes after the line in the first photo. Now it is clear that ice has formed, the crystals are growing and falling out as "virga", and a clearing is starting to open up.

Ice grows rapidly in the presence of the supercooled drops. Ice represents something of a low pressure center in the middle of all those droplets and that attracts the vapor from them, causing them to evaporate. That vapor deposits as ice on the newly present ice “germs”/crystals created by the aircraft. Since the drops are disappearing, before long, you get a hole or ice canal in the cloud where the droplet cloud used to be.

APIPs REDO_076 — In this third photo, there is no longer any doubt about what's is going on. The hole is there, and its only a question of how much larger it will get.

The ice crystals shown above are clearly falling out (ever-so gradually because they are so small still, perhaps a few hundred microns in width). Becasue they are so small, they usually evaporate well before any precip reaches the ground. However, recently it has been shown that in deeper clouds and more moist conditions, that an aircraft can actually produce a bit of rain/snow at the ground due to this effect.

Here is last photo I took that day.

The ice crystal induced hole in the Altocumulus layer has gotten closer to exiting the liquid cloud (has moved to the edge of it) as well as expanding some. This suggests that the ice cloud was moving faster than the droplet cloud, something that happens when waves in the atmosphere are producing the droplet cloud. It was also getting closer to the observer, however.

Sometimes, if the cloud layer is lifting enough, the original Altocumulus clouds will gradually fill back in because all of the ice has settled below the liquid cloud layer.

For history buffs, holes in clouds with ice in the center, or ice canals were seen in the 1930 and 1940s, but as you can see, unless the observer saw the original trail (which they usually didn’t) no one knew what caused them. Eventually an ice canal was was photographed in 1946 that was so convoluted it was realized that ONLY an aircraft could have done it.

Furthermore, that report in 1946 preceded the discovery of modern cloud seeding with dry ice by Vincent Schaefer in 1947 who performed his most convincing, and could be seen as ironic, demonstration of seeding with a similar convoluted ice canal as was seen in 1946 in a supercooled Altocumulus cloud layer Its interesting in retrospect, as so many things are, that Schaefer did not have to drop dry ice on his clouds that day in 1947 in which he made history, but rather only had to fly his prop aircraft through them and likely would have gotten the same effect!

BTW, there is a lot of new interest in this topic, a new article recently appearing in Science mag.

I mention this cloud seeding benchmark since these aircraft events represent inadvertent cloud seeding, and in a sense they demonstrate that you CAN get something in the way of precip to fall out of a previously non-precipitating or barely precipitating cloud by seeding. When clouds are already naturally precipitating, what happens when you do cloud seeding is subject to question; the science domain in this murky world is highly polarized.

The “Story of APIPs”–Aircraft-produced Ice Particles) is told (in the usual “style” you will often find here) in the gigantic powerpoint “show” on this website under Sci Talks toward the middle of the show, around slide #472 (hahaha).

This ppt “show”, BTW, is WAY overdone, but, what the HECK! Why tell only “the whole 9 yards” when you can tell 12 or 14?

^{———————————————————————————————————————————————————-}

¹Hahaha, sort of. Sometimes, looking at those several thousand film shots from the rooftop of the Atmos Sci Building, I do wonder about that. But then again, since I used 1/100 of a second exposures with my film cameras, these photos would only PROVE that I had been on the roof, maybe 30 seconds in 30 years there at the UW.

Feeling better now.

What’s Up with This?

Got pretty mad yesterday when I saw this overhead in some Altocumulus perlucidus clouds. You’ll have to hold your monitor or Ipad, or cell phone, or whatever, over your head to see it EXACTLY the way I saw this because it WAS overhead; straight up. (Actually, doing 3 sets of 12 might be good for you.) Also, click on images to get the full view.

As you can see, the white strip below in these clouds is a contrail caused by an aircraft, but a special one that occurs in “supercooled” clouds. Supercooled clouds are clouds that are composed of drops, yep, they’re still liquid, even though the temperature is FAR below freezing. Here, the clouds were likely colder than -20 C (-4 F) and yet there is no ice forming in them! (You don’t see trails of snow coming out, do you? No.) Run of the mill contrails occur at cirrus levels at temperatures below about -35 C (-31 F).

Note that except for being much whiter than the surrounding cloud, the elements are exactly the same size and texture as those around it. That is going to change, because this white strip is composed of “horrendous” concentrations (probably thousands per liter) of ice! You can only know this by what happens later.

In the next shot below, is an example of what happens later, trails of tiny snow crystals fall out leaving a hole in the droplet cloud, so called, “hole punch” clouds, a form of inadvertent cloud seeding by aircraft. Note the delicate strands of ice crystals falling out of this cloud from the hole, so pretty because they are so delicate looking. Note, too, I am one of the “trailing authors” of the journal article above, like one of those itty bitty ice crystals in the second photo which are almost evaporated at the bottom of those fine strands.

So why be upset?

Rather than looking forward to good things in the coming year, this happenstance yesterday reminded me of all the trouble we had in the early 1980s trying to get our paper published on this phenomenon; namely, that an aircraft could produce tremendous amounts of ice when flying through supercooled clouds, inadvertently seeding them.

In the SECOND rejection of our manuscript (with Pete Hobbs), the Editors words still burn; “(the reviewers) are still unconvinced by these controversial claims.”

We had to do a LOT of extra work on this to convince those reviewers. The third version was more convincing, I guess, for intransigent reviewers, and got published. In fact, one of the great scientists of our time as far as clouds and ice crystals go, John Hallett (yes, the same one as in the “Hallett-Mossop” ice splintering process), speaking at the Peter Hobbs Symposium Day in 2008 called this episode, “an embarrassment for the airborne research community.” “Hey”, he wasn’t referring to our paper!

He was referring to the fact that such a phenemenon had been overlooked and not accounted for in research studies of clouds by aircraft. Actually ground observers had been reporting this kind of thing (ice canals and hole punch clouds) since, if you can believe it, the 1930s!

BTW, this hole is not the one from the first shot; I got distracted and forgot to follow it until it was disappearing over the horizon.

BTW#2,, this shows what happens when you introduce ice into a supercooled cloud; “stuff” falls out. Proves cloud seeding works, though for sure in limited venues like these (non-precipitating, supercooled clouds).

BTW#3: The second photo is a nice example of the difference between supercooled clouds composed of tiny drops (probably less than 20 microns in diameter), and cirrus-ee ice clouds, composed of much larger crystals (here probably 100 or 300 or so microns in maximum size) that tend to settle with time. (Hence, those strands in most cirrus clouds.

BTW#4: Today’s title is cribbed off the world’s most viewed climate website, “What’s Up With That?” Mr. Watts, host of the site, has made significant contributions to our climate network by pointing out flaws, but has no “credentials” beyond having been a TEEVEE meteorologist. He is excoriated on this point alone by “credentialists”, as I myself was when I first began to reanalyze other folks’ cloud seeding experiments such as this one.

BTW#5, a movie about credentialism is now out, called, “The King’s Speech.” I highly recommend it. In this documentary, which I just saw yesterday, it will be seen that the credentialists in the King’s Court were royally put out by the help the King got by his uncredentialed therapist.

Cirrus clouds overhead now

These clouds, the very first ones usually precursors of disturbances, are overhead now with the airways crossing Arizona evident in the “condensation trails” (contrails) showing their positions. FORTUNATELY (the writer despises contrails), there are few overhead of Catalina-Tucson area because there are few airways overhead. Most of our contrails are to the north of us, likely representing cross country flights to Los Angeles. As some may know, contrails are considered a sky contaminant over such national treasures as the Grand Canyon. Also, with air travel predicted to double in the next ten years, more of them are likely to spoil more and more skies. (OK, this is a first shot at writing anything on a web page, so if anyone sees this, please forgive errors in constructing proper sentences.) Expect to upload cloud photos with some discussion of what is being looked at before too much longer.