Category Archives: Parhelia (sun dogs)

A stragne and wonderful day

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.

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7:24 AM. Here, a tiny highlighted flake of Altocumulus floating above a mass of light snow/ice crystals, maybe straight below it. This is one the classic mysteries we deal with in “cloud microstructure”;  the oddity of nature preferring to generate a droplet before an ice crystal at least to somewhere in the -30°s C. Liquid clouds often are at the top of Altostratus and Nimbostratus (rainy or snowy days) providing the tops aren’t too much colder than -30° C. How strange is it to have liquid water at the lowest temperatures in a cloud system, with all the ice and snow underneath, as shown in this photo (though here they are no longer connected).
7:24 AM/ I think there is itty bitty droplet cloud at the very top bright dot there.
7:24 AM/ I think there is itty bitty droplet cloud at the very top bright dot there.  A droplet cloud was likely much broader to have produced all the ice we see below that bright dot of liquid cloud.
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7:26 AM. Looking afar, to the SW, there’s what appears to be an Altocumulus (droplet cloud) with a few ice crystals underneat it, especially to the right.

How cold are these clouds?  Lets look at the TUS sounding, launched at about 3:30 AM yesterday morning.

The TUS rawinsonde balloon data for yesterday morning before dawn.
The TUS rawinsonde balloon data for yesterday morning before dawn.  That Altocumulus layer, and the other clouds above were likely at the pinched point above, topping out at -27°C and up around 23,000 feet above sea level (400 millibars), pretty darn cold.  But, as you saw in the 3rd photo, not a lot of ice is being generated at this temperature by that patch of Altocumulus clouds to the SW.  Not sure why, but its pretty remarkable and that is likely due to small droplet sizes AND a lack of ice nuclei, most of which are known to originate with soil particles  When you see these rare occurrences of all or mostly droplet clouds at low temperatures (<-20° C in particular, get ready to see hole punch and ice canals produced by aircraft, a kind of inadvertent cloud seeding.

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.

7:55 AM. This is one of the strangest sights I have ever seen. Why? On the left side of this photo, the clouds are completely glaciated, composed of ice, while along a line to the right, there's no sign of ice in Altocumulus clouds that appear to be at the same height (namely, temperature). I have no explanation for this scene, except those involving a lot hand-waving, so we'll just let go.
7:55 AM. This is one of the strangest sights I have ever seen. Why? On the left side of this photo, the clouds are completely glaciated, composed of ice, while along a line to the right, there’s no sign of ice in Altocumulus clouds that appear to be at the same height (namely, temperature). I have no explanation for this scene, except those involving a lot hand-waving, so we’ll just let go, except that we speculate that the Ac layer was a little lower (warmer)?  Could have been.

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:

8:16 AM. An icy canal due to the passage of an aircraft rips through this pristine layer of Altocumulus whose temperature was around -25° C.
8:16 AM. An icy canal due to the passage of an aircraft rips through this pristine layer of Altocumulus whose temperature was around -25° C.  The view is looking S toward Tucson, but is unlikely to have been an aircraft landing there because this layer was above 20,000 feet Above Sea Level.  An aircraft lanidng at TUS would be much lower, this close.  The passage of the aircraft was likely 10 or more minutes before this photo.
8:19 AM. The ice canal is broadening due to turbulence, and ice is not plainly evident to all Cloud Maven Juniors or we will have to go over discerning ice from droplet clouds at the next club meeting.
8:19 AM. The ice canal is broadening due to turbulence, and ice is not plainly evident to all Cloud Maven Juniors or we will have to go over discerning ice from droplet clouds at the next club meeting.
8:20 AM. A view of the northwest end of this aircraft-produced ice canal. Several others became apparent, too.
8:20 AM. A view of the northwest end of this aircraft-produced ice canal. Several others became apparent, too.

Heading for Catalina, this:

9:11 AM. Heading for Catalina, a whole mess of aircraft induced ice in that poor Altocumulus layer. The hole punch was likely due to an aircraft climbing out of or descending into TUS. The age of a hole that large, with ice below it like this would be something of the order of at least half an hour to an hour old. Just behind the hole is a new contrail in the Ac clouds,
9:11 AM. Heading for Catalina, a whole mess of aircraft induced ice in that poor Altocumulus layer. The hole punch was likely due to an aircraft climbing out of or descending into TUS. The age of a hole that large, with ice below it like this would be something of the order of at least half an hour to an hour old. Just behind the hole is a new contrail in the Ac clouds,
9:23 AM. Hole punch area and ice canal arrive over Catalina! Losing control here, taking photo and photo, now looking for stragne optics, usually observed with aircraft produced ice particles because they are so numerous, compete for the available moisture and therefore remain tiny and perfect, prisms, plates, short column ice crystals, ones that can do a lot of optical stuff.
9:23 AM. Hole punch area and ice canal arrive over Catalina! Losing control here, taking photo and photo, now looking for stragne optics, usually observed with aircraft produced ice particles because they are so numerous, compete for the available moisture and therefore remain tiny and perfect, prisms, plates, short column ice crystals, ones that can do a lot of optical stuff.

Here’s the south end of that ice canal:

9:24 AM.
9:24 AM.  Also note iconic horse wind vane, and real wind vane atop a personal weather station.  Doesn’t everyone have a “PWS”?

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!

9:27 AM. Look at the detail in the ice, those fine, fine strands! Amazing. The thickest strand might be due to the higher liquiid water in the heart of one of those little Altocumulus cloudlets. ???
9:27 AM. Look at the detail in the ice, those fine, fine strands! Amazing. The thickest strand might be due to the higher liquiid water in the heart of one of those little Altocumulus cloudlets. ???  Look how much wind shear there is, those little itty bitty ice crystals falling so far behind the parent cloud, the streamers flattening out because the poor little guys, already undersized to begin with, are getting smaller and smaller, the fall velocity getting less and less until the strands are almost horizontal.
9:27 AM. Looking at this gorgeously uniform layer of Altocumulus perlucidus 9honeycomb of elements) translucidus (no shadows).
9:27 AM. Looking at this gorgeously uniform layer of Altocumulus perlucidus 9honeycomb of elements) translucidus (no shadows).  To me this is a phenomenal scene, though maybe to u, not so much, which is understandable.
9:30 AM. The expected intense optical phenomena began to occur in these aircraft contrail remains.
9:30 AM. The expected intense optical phenomena began to occur in these aircraft contrail remains.  Here a parhelia, or sundog.  More fireworks in a bit.
9:30 AM. While the parhelia was in its full display, very intense, this was the ice canal passing overhead. Look at the regular spacing of these strands of ice, Might be due to the spacing of the cloudlets in the Altocumulus layer, the spaces between them not producing much ice, or, as we know, contrails tend to clump behind the aircraft likely due to wingtip vortices interacting and combining masses of exhaust water and crud.
9:30 AM. While the parhelia was in its full display, very intense, this was the ice canal passing overhead. Look at the regular spacing of these strands of ice, Might be due to the spacing of the cloudlets in the Altocumulus layer, the spaces between them not producing much ice, or, as we know, contrails tend to clump behind the aircraft likely due to wingtip vortices interacting and combining masses of exhaust water and crud.   This is now about an hour and fifteen minutes old, since we saw it way out to the west at 8:16 AM shortly after it formed.
9:37 AM. Here's what a new aircraft contrail in these clouds looks like, this one about 60 s old looks like
9:37 AM. Here’s what a new aircraft contrail in these clouds looks like, this one about 60 s old looks like.  Note all the irregularity in the contrail from the get-go.

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.

9:44 AM. Halo curving in the wrong direction, away from the sun!
9:44 AM. A part of a halo curving in the wrong direction, away from the sun! (This is actually called a circumzenithal arc).
9:44 AM. Taking up you up thousands and thousands of feet via a zoomed view.
9:44 AM. Taking up you up thousands and thousands of feet via a zoomed view.   Pretty cool, eh?  Notice how much its moved in just seconds,  You really have to let your coffee get cold if you’re a photographer and you want to get the best shots of this kind of phenomenon.  You really can’t do anything but keep watching every second!
9:44 AM, again. All these changes took place within the minute between 9:44 and 9:45 AM!
9:44 AM, again. All these changes took place within the minute between 9:44 and 9:45 AM!  Here, the next grouping of ice strands is being lit up.
9:48 AM. Just a pretty scene. Altocumulus perlucidus translucidus, pocked with aircraft contrails, if you look real close.
9:48 AM. Just a pretty scene. Altocumulus perlucidus translucidus, pocked with aircraft contrails, if you look real close.  Make me move:  $1 billion dollars…
9:54 AM. Its not even 10 AM and now this comes along, this fabulously complex zone of CIrrocumulus (at the same level of the Ac clouds) at the tail of the Altocumulus. You can see the much higher Cirrus going crossways, lower center. See TUS sounding for height of Ci.
9:54 AM. Its not even 10 AM and now this comes along, this fabulously complex zone of CIrrocumulus (at the same level of the Ac clouds) at the tail of the Altocumulus. You can see the much higher Cirrus going crossways, lower center. See TUS sounding for height of Ci.

Then this strange sight:

12:29 PM. A row of Altocumulus or Cirrocumulus, each formed by a little upward bump in the atmosphere of a layer just a hair below saturation. Just rising a few hundred feet or so causes these cloudlets to form. Why aren't they everywhere? Might be drier. Bumps like this are always present in the atmosphere, especially if there are mountains upwind.
12:29 PM. A row of Altocumulus or Cirrocumulus, each formed by a little upward bump in the atmosphere of a layer just a hair below saturation. Just rising a few hundred feet or so causes these cloudlets to form. Why aren’t they everywhere? Might be drier. Bumps like this are always present in the atmosphere, especially if there are mountains upwind.  Not taken while driving, of course, ; just looks like it thanks to photoshop.

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:

2:09 PM. Altocumulus perlucidus translucidus. A natural conversion to ice is occurring on the right side of the photo.
2:09 PM. Altocumulus perlucidus translucidus. A natural conversion to ice is occurring on the right side of the photo.
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4:42 PM. So pretty these Altocu.

 

4:41 PM. A strand of finely patterned Cirrocumulus shot out of the SW as the sun declined.
4:41 PM. A strand of finely patterned Cirrocumulus shot out of the SW as the sun declined.
The Tucson afternoon rawinsonde . launched around 3:30 PM.
The Tucson afternoon rawinsonde . launched around 3:30 PM.  The Cirrocu in the above photo was likely also at the Cirrus level indicated above.

U of AZ mod thinks so light rain will develop around here in the mid-later afternoon.

The End

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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.

Ice optics extravaganza; Cirrus uncinus fallstreifen going in different directions!

What a day, Mr. and Mrs. Catalina!

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.

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The balloon sounding launched around 3:30 PM AST yesterday from the Banner University of Arizona.

Some photos documenting the excitement of yesterday

5:30 PM. Cirrus uncinus crystals heading in two very different directions. Wow. Notice the fibers from the contrail that are starting to fall out are going in the "correct" direction, back toward that west.
5:30 PM. Cirrus uncinus crystals heading in two very different directions. Wow. Notice the fibers from the contrail that are starting to fall out are going in the “correct” direction, back toward that west or southwest.
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3:04 PM. Parhelic circle erupts in mostly Cirrus uncinus clouds.
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3:06 PM. The astounding sight continues, but fades away just after this.
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3:33 PM. Local brightening at the position of a sun dog suggests these are tiny ice crystals or possibly even droplets that have just formed, the sizes too small to allow refraction into color normally seen in sun dogs.
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3:32 PM. A zoomed view of that little bright spot. Sure looks like it may have been droplets. Droplet clouds have been reliably reported to temperatures as low as -44° C. Of course, wouldn’t stay liquid long!  I thought this was a pretty exciting shot!  Hope you got it, too.

 

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3:42 PM. Amid all the optical excitement was this ghost-like halo. Can you make out the faint circle around the sun? In ascents through thick ice clouds having complicated ice crystals like bullet rosettes down below the tops, as you climb to the top of such clouds, amazing haloes can be seen where the crystals are newly formed and quite simple in structure, allowing the refraction required for a halo. So, this halo was likely at the top of these thicker Cirrus and Altostratus (dense portions) clouds, though no one would penalize you if you just said they were all Cirrus clouds.

 

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3:59 PM. Another spectacular bright spot at the sun dog location (which is also at the 22° halo location, faintly evident here).
3:59 PM.
3:59 PM. Zoomed view of this sun dog/parhelia. Lots of fine structure evident, which is not usually the case with parhelia.
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4:25 PM. Another finely structured parhelia/sun dog suggesting the ice crystals were newly formed. Fine structure like this can’t last long with the usual turbulence, and so that’s a sure sign this feature has just formed.  I don’t recall seeing so many atypical sun dogs in one day!
5:09 PM. The normal, amorphous sun dog. No really fine detail can be seen here.
5:09 PM. The normal, amorphous sun dog. No really fine detail can be seen here.

Below, examples of cold Cirrocumulus, ones that quickly transition to Cirrus clouds.

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5:19 PM. This group of CIrrocumulus clouds appeared very quickly almost overhead. The tiniest elements are those that have just formed. These are composed of ice crystals in extremely high concentrations, perhaps 10,000 per lilter. Once that ice has formed, its gradually spreads out, much like a puff of smoke would, thinning, some crystals growing large enough to start fall steaks.
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5:19 PM. Some elements are still forming, but the spreading of the older ones is well underway, producing a “blurred” look as the elements merge and thin out.
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5:28 PM. Off to the southwest of Catalina, a promising intrusion of lower moisture indicated by these approaching Altocumulus clouds. Will there be enough today for a sprinkle somewhere?  Not looking so good now, clouds did not lower much overnight.   Well, maybe if it doesn’t sprinkle, maybe we’ll get to see some nice virga and dream about rain…

 

The End

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1I was going to call it something else.  Egad.  Let us remember the words of the B-52s:  “Before I talk, I should read the book.

Cirrus enigma; medium-sized Cumulus clouds snow away

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.

1:15 PM.  That tuft of Cirrus on the right seems to have trails of ice falling out then coming together.  There is no explanation for this since the wind has to blowing 1) from the same direction at the head, and then changing direction/speed ("shear") at the same rate underneath the cloud.
1:15 PM. That tuft of Cirrus on the right seems to have trails of ice falling out then coming together, almost like they missed each other and want to be together as snow trails until evaporating away.   There is no explanation for this2 so I will next post a distraction. (Remember, when you can’t explain something, and this is a life hint, you can either talk around the question without answering it,  beginning with, “I’m glad you asked me that question…..” when you’re lying and really NOT glad, or launch a distraction.  Here, we launch a distraction.

“I don’t know how that happened; let look at a flower instead”:

Seen yesterday morning on a dog walk.
Seen yesterday morning on a dog walk, evening primrose.  Pretty restful image; problems gone…

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:

7:17 AM.  Riff of Altocumulus castellanus/floccus to the north.  Remember in Cloud Maven's Person's poster-sized cloud chart it says when you see this cloud it could rain in 6 to 196 hours, as it does for all the clouds in it.
7:17 AM. Riff of Altocumulus castellanus/floccus to the north. Remember in Cloud Maven’s Person’s poster-sized cloud chart it says when you see this cloud it could rain in 6 to 196 hours, as it does for all the cloud formations in it.
7:18 AM.  Iridescence in a patch of Cirrocumulus, indicating that the droplets comprising it were very tiny, less than 10 or so microns in diameter (one tenth the diameter of a human hair).
7:18 AM. Iridescence in a patch of Cirrocumulus, indicating that the droplets comprising it were very tiny, less than 10 or so microns in diameter (one tenth the diameter of a human hair).  It could rain in 6 to 196 hours when you see this cloud….
9:43 AM.  Cirrus, various species, overspread the sky.  Blockage of some Cirrus by a bird of some kind, lower center.
9:43 AM. Cirrus, various species/varieties overspread the sky. Blockage of some Cirrus here by a bird of some kind, lower center.

Moving ahead…..

1:14 PM.  The cloud-maven cloud indicator blimp was positioned to draw your attention to some building Cumulus clouds southwest of us.  No ice evident.
1:14 PM. The cloud-maven cloud indicator blimp was positioned to draw your attention to some building Cumulus clouds southwest of us. No ice evident, but was soon after this shot.

 

2:47 PM.  Cumulus complex shows no ice, but its up there inside, as you would have known from looking at other similar-sized clouds.
2:47 PM. Cumulus complex shows no ice, but its up there inside, as you would have known from looking at other similar-sized clouds.
3:02 PM.  Droop der it is!  Virga, there it is, downwind end of cloud stream.
3:02 PM. “Droop,  there it is!” Virga, there it is, drooping out just below the farthest cloud bottom downwind end of this cloud stream.
3:17 PM.  Virga's pretty obvious now.
3:17 PM. Virga’s pretty obvious now (above that protruding tree in the distance.  Cloud that produced this virga likely no thicker than the white backed one at the start of the cloud stream, etimated depth, 2000-3000 feet.  Bases, however, were about -8 to -10 C (18-14 F)!  Tops, of clouds even that shallow,  were really COLD, maybe to -15 to -20 C (down to 4 F)!  But you would have guessed this anyway based on the amount of ice coming out of such shallow clouds.  Sorry to insult your Cloud Maven Junior intelligence..
3:23 PM.  Getting excited here so zoomed in for you.  A sprinkle of rain was likely reaching the ground
3:23 PM. Getting excited here so zoomed in for you. A sprinkle of rain was likely reaching the ground.  Here you can see how cold the cloud bases were since that whiteness in the shaft is snow.  Where it has completely melted into rain drops is where the bottom of that whiteness ends,  The freezing level is typically about a thousand feet higher than where than whiteness ends below cloud base in steady, not too heavy precip, which is what we have here.  Small clouds can’t precip too much.  That snow is hanging down about 3,000 feet.
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4:34 PM. A streamer of shallow clouds forming ice heads out from the south toward Oro Valley from Tucson. Estimated depth, 2000-3000 feet is all.
4:34 PM.  Zoomed view of some of the ice in this cloud with an education module inserted into the photo, wrecking it some.
4:34 PM. Zoomed view of some of the ice in this cloud with an education module inserted into the photo, wrecking it some.  Concentrations here likely around 1 per liter of ice crystals.  If depth correct, the crystal habit will be stellars  (“Christmas card” crystals) and dendrites, ones that form between -13 C and -18 C.
The TUS balloon sounding (AKA, rawinsonde for technophiles) launched around 3:30 PM AST yesterday afternoon (from IPS MeteoStar).
The TUS balloon sounding (AKA, rawinsonde for technophiles) launched around 3:30 PM AST yesterday afternoon (from IPS MeteoStar).  Sounding calculates a cloud base of about -9 C, at about 10,000 feet above the ground (over Catalina).   That is cold!  Cloud base is just about where the two lines come together at the bottom.
5:46 PM.  Mock sun or parhelia; couldn't tell if is was due to the lower ice cloud, or a Cirrus way above.  Caused by hexagonal (six-sided) plate-like crystals falling face down.
5:46 PM. Mock sun or parhelia; couldn’t tell if is was due to the lower ice cloud, or a Cirrus way above. Caused by hexagonal (six-sided) plate-like crystals falling face down.  What a great optical phenomena day it was for you, starting out with a nice iridescence!
6:25 PM.  Sunset photos continue to get later and later.  These shallow clouds continued to produce virga into the evening hours.
6:25 PM. Sunset photos continue to get later and later. These shallow clouds continued to produce virga into the evening hours.

There’s still water in the Sutherland Wash.   Its been running now since the end of January!  Amazing.

The End

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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….

Another fireball over Tucson! Backwards halo seen, too! Rain on tap

Check these out in yesterday’s “Olympics of optics” where all kinds of goofy optical things were seen:

3:19 PM.  Fireball crosses Tucson skies.
3:19 PM. Fireball crosses Tucson skies leaving long plume of “smoke.”  Photo not touched up in any way shape or form because that would be wrong.  Note: always carry your camera with you since you only have seconds to capture something like this.
3:19 PM Fireball crosses Tucson skies 2.
3:19 PM Fireball crosses Tucson skies 2.

 

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3:57 PM. Then there was this “wrong way1” partial halo a few minutes later.  Could it be another  sign of climate change, as almost everything that happens is? The sun is below the bottom of the photo; haloes are supposed to go around the sun not around nothing.  When a partial halo around nothing occurs like this, its called a “circumzenithal arc”  caused by tiny, pristine ice crystals like hexagonal plates.   If you want to read about optics of all kinds, go  to the University of Washington Huskies weather department where they have optics chapter online.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4:10 PM.  Contrail passes through or above Cirrus uncinus.  Yesterday was one of the top (worst) days for contrails above and in view of Catalina IMO.
4:10 PM. Contrail passes through or above Cirrus uncinus. Yesterday was one of the top (worst) days for contrails above and in view of Catalina IMO.  Note lines of contrails above and behind weather station. We hope it was due to an unusual confluence of conditions such aircraft flying a heights different from normal due to a peculiar wind profile, Cirrus moisture at the level of the airways, that kind of thing since we rarely see as many as yesterday.

 

 Today’s clouds

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.

Rain?

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 tommorow….

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.

The End

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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.

 

 

 

Last chance for August rain?

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.

Catalina summer rain frequency chart
Looks like it needs to be updated…..

 

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.

Here are some pretty cloud scenes for you:

DSC_0154

11:01 AM.  Ice is obvious here. But, what kind of ice? If you look closely you can see that the ice crystals in this glaciated turret are comprised of hollow sheaths and needles, since the top of this cloud modest;  not that high and cold.  Well, that’s what I thought, anyway, just something about the texture…. Those kinds of crystals form at temperatures higher than -10 C (14 F), which is an unusual occurrence in Arizona. Happened yesterday because cloud bases were warm to start the day (about 10 C, or 50 F). Huh? Seems like a non-sequitur. “Strangely believe it”, as we like to say here, ice forms at higher temperatures as the bases of the clouds get warmer because ice formation is tied to drop sizes. The warmer the bases, the larger the drops reaching the freezing level in Cumulus turrets, and those  larger drops freeze at higher the temperatures.
DSC_0213
6:27 PM.  A parheila or sun dog, or mock sun in Altostratus cumulonimbogentius (of course). Caused by ice crystals falling flat on their face, hexagonal plates, pristine ones,  without any riming (cloud drops that have bumped into them and froze)
DSC_0217
7:02 PM.  Evening Cumulonimbus with a nice rain shaft; sent a few bolts “down” which is technically incorrect since the most luminous thing you see is called the “return stroke” and actually is going from the earth to the cloud.)
DSC_0150
11:01 AM.  Small Cumulonimbus forms over the Catalina Mountains. The turret on the left side is still mostly water, but would have a lot of small ice crystals in it. The center of the photo turret has glaciated, few or no liquid droplets exist.
DSC_0210
6:26 PM.  Cumulus highlighted by the setting sun under Altostratus or Cirrostratus (take your choice–Cs can have shading late in the day, otherwise, no shading for Cs. So pretty a scene.
DSC_0145
Just a nice closeup of a Cumulus turret. The variation in shading displays the complicated arrangement of liquid water content in the cloud, those darker areas having more.
DSC_0142
9:43 AM.  Going up? The Cumulus began forming on the Catalinas about 9 AM, a pretty early start, and that, a good sign of Cumulonimbi in our future.
DSC_0203-1
5:24 PM.  Just another just a pretty scene with Cumulus humilis and congestus.

The End.

Interesting optics yesterday; substantial rains just ahead

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.DSC_0162 DSC_0164 DSC_0169  DSC_0191 DSC_0194 DSC_0198

The End, back to work….

Dusty parhelia

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.

CIrrostratus fibratus with a faint 22 degree halo.
The denser portions tend toward Cirrus spissatus, but several other species are also present.
Faint sun dogs or parhelia located horizontally from the sun on the fainter halo
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.

Continuing….

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.

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.