Many strange1 and wonderful sights were seen yesterday; I could feel the excitement out there as one cloud microstructural mystery after another regaled our Catalina skies.
How cold are these clouds? Lets look at the TUS sounding, launched at about 3:30 AM yesterday morning.
That bank of Altocumulus was racing at more than 50 mph toward Catalina, and so it got here in a hurry. And, as it got closer, it was also getting more into some airways at that height, possibly descents into PHX since the height of those clouds was below normal jet cruising levels at 23,000 feet Above Sea Level.
Now for the aircraft effects. Hardly a few minutes go by before aircraft began marking up this cold Altocumulus layer. Notice that it doesn’t seem to be producing much or any ice on its own, making aircraft inadvertent seeding lines and holes where tremendous numbers of ice crystals are generated immediately present. Here’s the first of many:
Heading for Catalina, this:
Here’s the south end of that ice canal:
Looking straight up at the icy heart of a hole punch region caused by an aircraft. I am sure you have never done this before! This is gonna be a great blog with all these new things for you!
As the south end of the original ice canal began to enter the refraction zone for simple ice crystals around the sun, usually at the 22° degree halo position, things began to light up with a particularly bright circumzenithal arc (more often observed on a halo) or colorful (in this case) partial “reverse halo”. The colors (iridescence) due to the refracting of light within very small ice crystals. Normally iridescence is seen near the sun in Cirrocumulus clouds or the then edges of other droplet clouds. Very exciting.
Then this strange sight:
The day closed out with a lower layer of Altocumulus moving in, this layer, according to the TUS sounding, at “only’ -17° C, and little ice detected. Below, at 2:09 PM:
U of AZ mod thinks so light rain will develop around here in the mid-later afternoon.
1“stragne” above, originally an inadvertent typo, but left in place as another cheap trick to get draw the curiosity of readers who might wonder what stragne is.
Not as good as a rain day with lightning, but yesterday did have its moments in the sky, enough to make the astrologers on Mt. Lemmon jealous with displays of parhelia (“sun dogs”, or “mock suns”), faint haloes, a rare parhelic circle, something you don’t see but once every year or two, and fallstreifen (fall streaks) from Cirrus uncinus clouds going in almost opposite directions, an extremely rare sight.
The rare “parhelic circle” is a local brightening often extending out from a parhelia (sun dog) at a sharp angle, which I just learned about here1. Usually you don’t see a whole circle, just part of one.
These optic displays are caused by ice crystals, of course, ones not too complex, but rather simple ones like prisms, short solid columns, bullets, and hexagonal plates. Some examples of these can be seen here.
The bottom of yesterday’s moist layer was just above 30,000 feet at a temperature of -35° C and extended all the way up to about 40,000 feet above sea level where the temperature were around -65° C.
Some photos documenting the excitement of yesterday
Below, examples of cold Cirrocumulus, ones that quickly transition to Cirrus clouds.
First, you should always begin your day, not with the breakfast of champions, but by reviewing the prior day’s clouds in the University of Arizona time lapse movie. Here’s what you will see:
Lots of Cirrus, varies species, Altocumulus, Cirrocumulus, a high temperature contrail go through some Cirrocumulus just after 4 PM, and flocks of medium-sized Cumulus clouds emitting ice.
First, one interesting, but inexplicable Cirrus scene. I know you were likely going to ask Mr. Cloud Maven Person, “Hey, what gives here?” I get a lot of calls like that1.
“I don’t know how that happened; let look at a flower instead”:
In the meantime, after being flustered over a cloud in the early afternoon, those Cumulus clouds aroiund, only two or three thousand feet thick were beginning to snow away, first way off to the south of us, then downstream of the Cat2 Mountains.
Here is the rest of your interesting and learningful cloud day yesterday:
There’s still water in the Sutherland Wash. Its been running now since the end of January! Amazing.
1FYI, this is a lie.
2I suppose someone could posit that “Dark Magic”, oops, “Dark Energy” may have caused those trails to “come together over me” , by Lennon and McCartney. “Dark Magic”, OOPs. “Dark Energy”, dammitall, is invoked to explain a lot of impossible things, like how the Universe blew up from something smaller than the head of a pin (!) and was 200 million light YEARS across in the tiniest fraction of a ONE second. Clearly impossible without magic, oops, Dark Energy. This impossibility was deduced on cosmic microwave radiation measurements at the farthest edges of the Universe as we know it.
However, instead of checking their measurements, cosmos (not Cosmos Topper of early movie fame with Carey Grant, but cosmos scientists that study the cosmos invented Dark Magic, oops, Dark Energy, dammitall again, to explain how something that’s impossible happened.
Recently, cosmos scientists retracted that finding and said their measurements in retrospect were likely compromised by cosmos dust. How funny izzat? Sure, I am a weather man and make a LOT of errors myself, but that cosmos one is pretty big.
Just kidding, cosmos guys, the cosmos is tough. Science mag reported that only 4 % of the visible Univserse is made up of known stuff, 96% (gasp) is made up of Dark Matter (23%), and 73%, of “Dark Magic”, oops again, “Dark Energy”, that stuff that is still thought to be behind the increasingly rapid expansion of the Universe3. That is, 96% of the Universe is composed of stuff we’re clueless about.
3It was originally posited that the expansion of the Universe should be slowing down until around the 1990s, when measurements indicated it was speeding up. Hmmmmm. Will there be a retraction of that claim, too, in our future? Stand by for more measurements. Just kidding, cosmos guys. Try being a weatherman….
Check these out in yesterday’s “Olympics of optics” where all kinds of goofy optical things were seen:
Thickening and lowering, ho hum, the usual as a trough aloft (bend in the jet stream winds up there) off southern Cal and Baja approaches today. Ahead of the bend in the winds, seen in the map below, the vast layers of air rise ever so gradually, something like cm per second. But, its enough to produce sheets of clouds.
What kind of clouds?
Heavy, dense and gray ice clouds we call Altostratus (As), with thicker and thinner spots should dominate the day. Then as the moist layer lowers, that is, as the As “bases”, really just comprised of falling snow that only looks like a solid bottom, get lower, patches of virga will start to reach the ground later today. Altocumulus ought to be around, too, water droplet clouds not cold enough to be completely iced up. Expecting those layer clouds, or undercutting layers to be low and lumpy enough to be termed Stratocumulus late in the day.
The strongest winds at 500 mb (around 18,000 feet above sea level) will be to our south beginning today, a necessary condition for virtually ALL wintertime rain here. CM is expecting some rain to fall in Catalina later today, or tonight as this bend in the winds aloft goes by. Expected amounts in this first wave, trace, minimum to 0.25 inches max by mid-day tomorrow.
Its really dicey situation since its not clear how deep the moisture is off Baja now, but looks potent enough for as much as a quarter inch from this keyboard, though less is more likely. Sorry the range is necessarily so great.
BTW, the WRF-GOOFUS model didn’t have ANY rain predicted for this time frame period in both of the 5 AM AST and 5 PM runs of yesterday. So, we’re out on a bit of a limb.
After 5 PM AST tomorrow, all peoples and models see more rain for Catalina as two waves/troughs barrel in right behind the first one that goes over tonight. The 2nd and 3rd ones produce a couple of rains through Thursday with big breaks likely in between.
The total amounts for Catalina between now and Friday morning still look like they will be contained within the range of 0.25 inches (things don’t go so well; disappointing really) and an inch (things go really well). Best guess is average of those, for a few day total of 0.625 inches.
1Remember “Wrong Way Corrigan”? Picked up that fumble and scored a TD for the other team? Maybe it was an early sign of the effects of concussions in fubball.
An unusually strong “trough” (a bend in the winds that points to the Equator) aloft will be moving across our region today, and as it does, it will be clustering storms, much like they were bunched together two days ago. Remember that those bunched thunderheads came through in a band about mid-day. Something similar is foretold for today, except a little later. We hope that it takes a little longer than about 25 minutes to go through today, too. Violent weather is expected in AZ today, too, with the PHX NWS office particularly worked up by this possibility and that office has already issued public advisories about frequent lightning, terrific winds, and huge dumps of rain.
Dry and fall like days will follow today…..meaning morning low temperatures will probably drop into the 60s here as the dry invading air moves over us. With the lower sun angle these days leading to deeper blue skies overhead, the lower morning temperatures, you will definitely be thinking about college fubball in the days ahead.
Pay especial attention to what Bob has to say, our premier senior heavy weather forecaster, and your NWS for watches and warnings. Mike at the U of AZ will be weighing in as well later this morning. Could it be a tube day, too, somewhere? Will be watching.
Not very certain there will be any more August rain here after this, a very dark thought. As you know the chances of rain start to decline at this time of year.
Yesterday’s clouds (not in chronological order, just because…)
Maybe I make it too easy for you every day…
Ice developed early and often in those morning Cumulus as they transitioned to weak Cumulonimbus clouds with tops that weren’t so high, but considering how early that happened, it led someone to think that it might be a really good thunderstorm day. But then the air aloft dried out and those Cumulus tops couldn’t reach the ice-forming level by afternoon, which was quite a disappointment for someone.
Pretty boring lately…. No motivation here, even after caffeinating royally every morning. Have had some pro work to work on, too, like reviewing a manuscript for a journal–loosely translated, work that’s largely comprised of “finding fault in the work of others,” which I am pretty good at, to be a little immodest. Due this weekend, too…
11 PM U of AZ mod has late afternoon and evening rains in Catalina! Yay. Looks pretty wet, too, through the middle of next week, some lucky places (Catalina/Oro Valley) might get 1-3 inches during that time I suspect. (Neck out pretty far here.)
But…another longish dry spell takes hold after that. Seems to be the character of our summer; a couple good, wet days, then a long dry spell.
Still there were some great cloud sights yesterday, and I wanted to share them with my reader, wherever you are.
Down at second from the bottom is the rare sun pillar, and the last photo, a kind of an odd parhelia (sun dog) since the clouds were mainly Altocumulus ones in which it was occurring and it was darn bright.
Parhelia normally occur in icy Altostratus clouds. I would guess that this one might have been caused by ice crystals produced by an aircraft that passed through that Ac layer toward the horizon, right.
No, that’s not a baseball player that played for the Dodgers or Giants back in the 1950s, that was Dusty Roads; though Dusty Parhelia would be a nice name for a baseball player. Yesterday, with our slightly dusty skies, and on the 22 degree halo ring, and horizontally from the sun’s position, was a couple of sun dogs (parhelia) late in the day associated with those cirriform clouds we had. You know by now that those high clouds are comprised of small ice crystals. Here’s a few shots of those clouds, which were often CIrrostratus with embedded other Cirrus cloud species like spissatus, fibratus, and uncinus.
The ice crystals in those clouds are typically hexagonal (six-sided) plates, ones that fall face down. If you could be there in them, and see them falling, at eye level you would see only the sliver side of them, but if you looked down at one that went by, you would see the whole hexagonal plate. The way that they fall is why aircraft laser imagery, when the laser is oriented in the vertical, captures such beautiful, full images of plates and other flat crystals in ice clouds as the aircraft flies through them.
The sun’s white light is separated into its colored components in these hexagonal crystals (but only at certain specific angles) and for this reason, the bright spots are at the same locations relative to the sun. Since I am not an atmo optician, I am relying on the links above to provide more complete, comprehensible explanations.
Note: Caption function stopped working again in WP for the fourth photo, and after half a dozen tries, will write it here:
Photo 4 caption: An especially vivid parhelia can be seen just above the horizon at lower left. The brightest ones like this are usually associated with aircraft contrails since those have high concentrations of pristine crystals. A flying saucer, or a bird with its wings closed at the instant the photo was taken, is also visible.
Sat image loop from the U of WA weatherfolk show lots more cirriform clouds in route to AZ next few days with occasional breaks. So, keep your camera ready for optics and sunrise/sunset color.
The weather ahead? Dusty cold snap.
“Dusty” is kind of the word of the day today.
Long foretold big Cal storm on the 12th-13th affects southeast AZ mostly with wind and dust on the 13-14th followed by unusually cool weather for mid-April. A hint of rain excitement for Catalinians has begun to show up in model runs, such as this one from the U of WA for early Saturday morning on the 14th. Yay.
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.