Cirrus clouds – Page 17

Sunrise and Cirrus splendor; the rarely seen Cirrus castellanus floats by

Gee, three days with a cloud or two over droughty Catalina! Yay! Here’s yesterday morning’s nice Cirrus uncinus (icy clouds with long trails).

Then, later that morning, the RARELY seen Cirrus castellanus sporting some mammatus (downward protuberances at the bottom) showed up. (I should note that some of the female atmos sci students at the U of WA preferred to call “mammatus” varieties, “testicularis”.) I mention this in defference to their preference.

These icy Cirrus clouds, whatever you call them, are probably the rarest of all Cirrus. The noticeable cumulus-like shape shown in the second photo is rare up there. Mainly a steep drop in temperature with increasing height up toward the top of the troposphere (the earth’s blanket of air that contains our clouds (moslty).

Turrets, or cumulus-like shapes in clouds like the “puff” of Cirrus in the middle of the second photo, are also thought to be driven by the release of the latent heat of condensation (in lower, warmer Altocumulus clouds) and latent heat of deposition in ice clouds). When condensing droplets or as an ice crystal, heat is released to the atmosphere. This is a HUGE factor in thunderstorms (a lot of heat is released during condensation in updrafts), frequent in cooler, mid-level clouds such as in Altocumulus castellanus, but, because there is so little water vapor at Cirrus levels, very unusual way up there. Yesterday’s cloud were likely forming around -40 C, at about 33-34,000 feet above the ground.

Below the Ci cas photo is a sounding from the folks at the U of WY. It hints at a steeping of the lapse rate just above the 250 millibar level (between the 200 and 300 on the left side), and also just below a stable layer or sideways “v” in the temperature trace up there.

I was quite pumped to see this rare display. Out of thousands of cloud photos, I have but a dozen or so of Ci cas. Unfortunately, it seemed, passersby in the Basha’s parking lot when this was about to go overhead, were non-plussed when I pointed out the unusual cloud. They were mostly polite, but generally said something like, “Huh?” It made me wonder what is happening to us if we can’t get excited about a Ci cas? I started to feel sad.

Later, in the afternoon, when the heavy ice clouds moved in (Altostratus translucidus and opacus) in the late afternoon, you probably were guessing that a good sunset was on tap. And you were right. Below an example of that Altostratus, followed by another neat sunset. Likely to repeat all this today.

Hey, get excited!

The End

“Smoke gets in your skies”

Remember that great Harold Arlyn song about smog? He was pretty upset when he wrote it I would imagine. Btw, the song was covered later in the 1950s by a group called The Platters…

Below we have a shot of some late afternoon pretty, undulating Cirrus or Cirrostratus… (NOT!)

That was a trick question, actually it wasn’t a question, but it was meant to trick you before you saw the exclamatory statement, “not!” Perhaps, I was thinking, you would seriously consider that this WAS a photo of cirrus for just that instant…but then you would be wrong!

But below, for those with the Calibrated Eye, found only in the most discerning of sky watching folk, you will IMMEDIATELY recognize that those waves, undulations in the sky above the tiny Cumulus fractus cloud at the right, is a smoke layer. Most likely 15,000 to 20,000 feet above the ground, that is, its also well below the normal Cirrus cloud level. This is, at present an “eyeball” estimate by yours truly. How can I find out the actual height? Maybe in the TUS rawinsonde balloon data. Smoke layers like this are often made visible by a moist layer because the smoke particles fatten up a bit and are made visible because they have gotten that bit larger and scatter more sunlight. So, this shot was taken near the time of the balloon ascent, and so I will now look and see if there was a bit of humidity around 20,000 feet above Sea Level (balloon data are reported in heights above sea level, not above ground level.) Farther below is the Tucson sounding from our friends at the University of Wyoming, which I had not yet looked at whilst (British spelling) writing the above.

As you can see, while there is a “pinching in” of the temperature and dewpoint traces representing the height of the Cumulus fractus moist layer, there really is nothing but a slight moistening (where the lines pinch in a bit) above that lower moist layer. So, it would appear that my hypothesis of a moisture layer enhancing the smoke layer should be rejected. But, as a scientist, I don’t care that I am wrong, because it is WRONG to care about whether you are WRONG as a scientist because we are detached from our hypotheses and only seek truth. Hon, could you get me a new pen since I just smashed this point on this one? Thanks.

BTW, if you were on a flight descending through this smoke layer, it would have appeared as though an ugly, thin black line of haze, because, after all, smoke is mostly hydrocarbons which are dark chains of molecules.

So why is it white here, when the sun is behind it? This is due to “forward scattering” of the wavelengths of sunlight, interfered with by those molecules of smoke, which are, in a sense dispersed. If you had looked to the opposite direction, to the east, you would not even have seen this layer. The tiny droplets in the Cumulus fractus cloud are really scattering the light around its edges where droplets are likely smaller than 10 microns in size, though at that size, about ten to a hundred times larger than the smoke particles.

The waves in the smoke illustrate the virtually ominipresence of waves in the atmosphere. We just don’t see them unless there is a smoke or cloud layer.

The End.

Not really, since I will, a bit later, see if I can post a trajectory that will show where this layer came from.

Sometime later…..

The last figure shows air trajectories for 72 hours at three different levels above ground level and each of the end points are at Tucson AP. Its clear from these trajectories that this “long range” transport haze layer shown in the first photo came out of the Pacific; it was not a part of any regional fires. Haze layers like this have often been observed to come all the way across the Pacific or even from Alaksa in the spring and early summer because the storms in the Pacific are weaker, and can’t wash the smog out. With the jet stream still very strong at levels of 10-30 kft across the Pacific at this time of year, these layers can then make it across pretty much intact.

Clouds to the north, clouds to the south, but not one in visual range from Cat land

Yesterday around this time I asserted that there would be some Cirrus and maybe some Altocumulus clouds for great sunset/sunrise photos last evening and this morning. In fact, there wasn’t and isn’t as I write, enough humidity at Cirrus levels for even obnoxious contrails! Bad forecast!

Here’s what Cirrus clouds looks like, in case you’ve forgotten and need a fix. They look like this because they are nothing but ice crystals gently falling out of the sky.

Will feel kind of sad today thinking about missing this cloud forecast. Maybe drink some extra coffee to help get through it.

The End.

Sunrise and sunset heaven: Cirrus and maybe Altocumulus on the way

Yep, a cute tiny little upper air low with just a dollop of high clouds is going to be spit out of the eastern Pacific off Baja Cal today and tomorrow and toward AZ, and along with that will come some Cirrus and probably Altocumulus floccus and castellanus clouds, maybe with virga. The first Cirrus cloud is likely to get here by late afternoon or evening today, and the sky should be full of high, icy Cirrus clouds tomorrow morning. So charge your camera batteries now for some of the “everyday-but stupendous” AZ color at sunset today and at sunrise tomorrow. You’ve been warned.

Below a map of the air flow and pressure patterns at 300 mb, or about 30,000 feet, the domain where cirriform clouds like to reside, valid at 5 AM LST this morning.

How Cirrus clouds grow up to be “uncinus” ones

What a glorious day yesterday was, if about 20 degrees F below normal! So much new snow on the Catalinas down to such low elevations for almost mid-April. Some sites in the Catalina Mountains reported over an inch of water content in that snow! Yay! Here in Catalina we had a bountiful 0.69 inches, more just to the north and west. Choose April 9th, and “Tucson” in drop down menu on this U of AZCats rain page to see the amounts around here. Truly a remarkable storm for April.

About those Cirrus “uncinus” clouds

How many saw those fabulous Cirrus clouds in the morning? Once in awhile, during the passage of Cirrus clouds you get to see how those long, delicate strands you often see by themselves, get that way, from their initial appearance to the end point; the long strands. Usually you can’t because Cirrus clouds are traveling so rapidly up there at 30,000 feet or so that they have gone over the horizon before much happens. Yesterday, an example of that “life cycle” passed overhead, moving from the W to the E at about 70-80 mph or so. In all of the photos below, the subject Cirrus cloud is in the upper right part of the photo.

Here then is most of the life cycle of a Cirrus cloud as it happened over Catalina. The starting point is that whitist cluster of little cloudlets, upper right. Those strands of Cirrus below that and that appear in rows to the lower left, are old dying cirrus clouds at the end of their life cycle. That top cluster in 1) has just appeared, probably only about 10 min old, and now the larger ice crystals are JUST beginning to leave the origin zone, much like a hiker reeling out rope to a friend stuck on a rock below. Those strands are like that rope having been let go of, then caught by the wind on its way down and stretched to full length while falling through the air. The remaining photos 3)-overhead view and 4)–leaving the scene, show that process continuing as the top cluster fades with longer and longer filaments of ice. In 4), you can see one strand in a side view as it speeds away revealing the lack of wind shear (changes in wind direction and speed) in the layer in which the cloudlets first formed. How do I and you know that? That one tiny filament that is straight up and down pretty much reveals that

You can now see how and why these delicate strands are there. Each long “rope” of ice represents one of the initial tufts that appeared within the cluster; each one has a contribution to make, a “rope” of ice to send downward. Almost always, except in deep storms, the strand of ice encounters drier and drier air and the crystals fall at lower and lower speeds until its negligible. The bottom, or lowest part of these strands then, have the tiniest of ice crystals, and the tail of the strand at this lowest point may appear almost horizontal if you could be up there.

The end.

Cirrus uncinus display; the tops of storms made visible

First, some instructional material: You should be looking for your camera now, as seen in the first shot! Those Cirrus clouds to the SW are moving at you rapidly (95 kts, 115 mph at 30-35 Kft ASL!), and so there’s not much time! In this first shot you can already detect some Cirrus uncinus, Cirrus clouds with hooked, or tufted tops in the center, with long icy strands trailing to the left. At this point perspective makes them bunch together so that they may not appear that “photogenic.” However, just wait! And, it was worth waiting just a few minutes for.

Take a lot at which they looked like passing overhead in the second and third shots, only about 7 minutes later. Just magnificent, some of the best Cirrus uncinus examples I have seen.

What is interesting about these clouds is that you are getting a glimpse of the structure of “stratiform”–that is, steady rain and snow storms that happen every day around the world, except that here in these photos, you are only seeing examples of the very tops of them. Those widespread rainy/snowy storms are usually packed with thousands of these kinds of clouds in a solid overcast up there, each “cell” shedding tiny ice crystals which then waft their way down, growing, perhaps merging into “aggregates” of ice crystals we call snowflakes, and, that most of the time except in Wisconsin in the winter, melt into raindrops as they fall below the melting level. Chances are, our little snowstorm of a few days ago had tops just like this.

Sometimes, clouds like these, and returns from vertically-pointed radars that can detect clouds like these, are referred to as “generating cells”, for obvious reasons. The trails you see here are clearly visible on very sensitive “cloud sensing” radars–they are not visible on “First Alert” Doppler style radars and such used by the NWS because the ice crystals are too small at this point to produce a return on “normal” radars. These cells form in a relatively shallow layer that usually lacks wind shear, likely mixed out by the little up and downdrafts in it. Its only after the crystals fallout that they encounter wind shear and end up being stretched out into “tails” as here.

Falling from heights of 30,000 feet takes a long time, for an ice crystal falling at only around 0.5 meters per second or around 1.5 ft a second or even less. It will take LONG time for anything to reach the ground, perhaps 2-3 hours to reach the melting level. So the little generating cell that produced a ice crystals at the top of major storms that grow and merge into snowflakes is likely over Alamosa, CO, and points northeastward by the time that flake landed on you at the ground with upper level winds such as we had yesterday.

I think its kind of interesting, but I may be the only one!

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.

Virga anyone?

Mr. Cloudmaven person foretold certain cloud types would occur yesterday in conjunction with “storm” 3 yesterday (which was really only the passage of an upper level trough over us–see map for 5PM yesterday). Let’s see how he did, that is, whether he is an actual “cloudmaven”:

(0=not observed, 1 observed, -1, cloud observed, not predicted:

Cirrocumulus, 0

Altocumulus floccus virgae, 0

Cirrus, 1

Cumulus fractus, -1

Cumulus humilis, -1

Cumulus mediocris, -1

Stratocumulus, -1

Stratocumulus virgae, -1

Cloud score: -4 =s bad cloudmaven; credentials suspect.

Here are some of the cloud sights from yesterday in case you miseed them and want to fill in some entries in your cloud diary: 1) 4:42 PM, 2) 5:26 PM, 3) 5:53 PM, has band of cirrus with trough passage, and 4) 6:12 PM, with some virga/ice fallout showing (darkish veils below clouds).

However, I did opine that there might be a sprinkle with this trough (see map again for example of yesterday’s “trough.” (Sounds like the stockmarket in ’09.) Having been specially trained to recognize virga and precipitation when a forecast of precipitation is on the line, I found it easy to recognize just how close I came to getting that sprinkle as evidenced by some virga trailing down from some of the patches of Stratocumulus clouds. See above hills in photo at left.

You now know, if you have been reading this blog and thinking about it all day, that ice formed in these clouds because they had crossed a temperature threshold, had gotten cold enough to form ice. That “virga” was, if you flew through it, snow flurries. Where it melted into raindrops closer to the ground is not visible. However, it is unlikely that virga of this magnitude reached the ground.

You might now even guess the temperature which the tops of the clouds reached. My guesstimate from the TUS sounding at 5 PM yesterday is somewhere between -15 to -20 C, a threshold for ice (precip) formation in shallow clouds such as these. Estimated depth of the thicker clouds seen here? About 2000 feet or so is all.

BTW, if you noticed these very subtle virga/ice in these Stratocumulus clouds that began to show up late in the afternoon, you are a cloud observer supreme!

Yesterday’s weather map:

The end.

Trick and treat sunset yesterday evening

Late yesterday afternoon, the sun appeared to be setting in the wrong location, about 20-25 degrees south of where it is supposed to be at this time of year. Perhaps something horrible had happened, I thought. Retirement with a happy ending here in Arizona was too good to be true, I thought, and now it was all going to come to an end. First, some perspective on where the sun was going down BEFORE yesterday. This first shot was taken just a few days ago (Feb 13th). Note where the sun is relative to the Tortolita mountains on the right, and Twin Peaks, the two itty bitty humps to the left. For further perspective, at the winter’s solstice, December 21st, and from this same location, the sun sets next to Twin Peaks. So, in this first shot you can also see how much the sun has moved in two months.

But then yesterday, something awful seemed to be happening. The next photo was one to send chills down your back, and in fact, if the sun was setting over there in the winter as a matter of routine, the northern hemisphere would likely glaciate down to about Blythe in the winter, due to the NH sunlight being so weak (that is, with so much tilt of the earth’s axis about which it spins). The days here would, in that case, be about the length of those in Seattle with daylight only from about 8-4 PM in the wintertime because the sun would be taking such a low trajectory in the sky; would rise late and sink early.

So, while I was concerned with the earth-sun system and some kind of apocalypse yesterday evening, I have feeling that most people were thinking, “Well, I guess we’re not going to have such a great sunset. Seems to be too many clouds over there where the sun is setting.”

Or maybe you were thinking about that important Washington Husky Arizona Cats basketball game today and how it might go.

But “No!”, a little later the sun underlit all those clouds, appearing to have sunk in its proper position for this time of year (3rd photo)!

I felt relieved and started thinking about that important Washington Husky -Arizona Cats basketball game today and how it might go. Then I also started thinking about how I might have been the ONLY person to notice something was terribly WRONG with that sunset. I feel pretty good about that part.

So, what happened? This “trick” sunset, followed by a treat of a sunset was caused by a parhelia (explanation by my friend, Bob, here) whose accessible name is “sun dog” or “mock sun”, which we CERTAINLY had in this case!

Parhelia appear, if you don’t go to the site above for a more complete explanation, when the ice crystals in the cirrus clouds up there are hexagonal plates, and fall with their faces down. The sun’s light is refracted (bent) as it passes through jillions of these plates and at about 22 degrees from the sun’s position, an observer on the ground will see a bright spot, sometimes with a little coloration. Sometimes there is also a “22 degree” halo along with the sundog.

I should add that the “trick” parhelia was being produced by ice crystals in the cirrus clouds above and behind the altocumulus cloud deck yesterday. Of course, as you know, altocumulus clouds are comprised completely or mostly of droplets and cannot, therefore, produce parhelia.

Finally, to end, the last shot is almost at the winter solstice, taken on December 26th, and has a parhelia, aka, sun dog, mock sun, at left so you can see what they usually look like and how far away from the sun they are near sunset. Yesterday’s, though, I thought was astoundingly bright and really made it look like the sun was going down in the WRONG place.

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.