“Pretty in Pink”

Well, “tending” toward pink, anyway…  But who remembers the Psychedelic Furs and what their song title alluded  anyway?  Of course, no one.  But I liked its dark sound.   Oh, well.

But here it is, that “pretty in pink” sky (2 shots) from yesterday evening in case you missed it.  Again these are Cirrus and Altostratus ice clouds with an isolated exception of Altocumulus lenticularis (just above horizon in the second shot), which is composed of droplets.  The second photo is a zoomed shot of the stack (several pancakes on top of one another) of a lenticular cloud off to the NW of Catalina.

Those lenticular clouds should always bring some excitement that things are changing, maybe heading toward a rain situation.   Rain did fall in the northern third of AZ when these Ac len clouds were present yesterday evening.

Why the excitement?

While these clouds don’t rain themselves, they are usually precursors of rain situations in the region because they illustrate that the winds aloft are relatively strong, the air in the “mid-levels” (roughly 10 to 20 thousand feet above the ground) has some moisture, and they indicate the kind of “stable” conditions in the mid-levels in their flatness, “pancaked-ness”, that precedes fronts.  Of course, we also had those moderate SW winds yesterday that also indicates that “something is going on”.

And something was going on as a cold front traversed the Great Basin yesterday.  Even this morning there is still precip in NW New Mexico as of 6:30 AM LST this morning.

And how do we know a new air mass came by?

The temperature change over the last 24 hours, from yesterday at this time to today at this time is one of the best ways of keeping track of fronts and changes in air masses.   Here is a plot of that 24 h change.  As you can see, the drop in temperature, while it has occurred at my gravel driveway (-5 F) is not quite here in Catalina (though it really is) according to the venerable The Weather Channel’s data which does not have my data (or pressure trace which has the usual sharp rise following a cold front–that heavier, denser, cold air is pushing down on all of us this morning and on my aneroid (not a body part, but a name for a barometer, BTW.)

The last shot here is what the clouds looked like before sunset.  Lots of gray indicating they are quite thick and fall into the Altostratus category even though they are very high.  Cirrus, by definition, cannot have this much grayness.  But, when you see this kind of  late afternoon sky, you can almost always count on a great evening scene, that sky especially “pretty in pink.”

Don’t see too many misspelled words, bad sentence structure and other grammatical lapses so will post this now…

@

 

 

 

 

 

 

 

 

 

In case you missed it…yesterday morning’s sunrise

A belated post, to be sure

Yesterday morning’s sounding when the Altocumulus clouds were overhead.  Bases about -18 C, tops -27 C.  Lots of ice visible along with widespread virga.  Whenever you see this much ice in small Altocumulus clouds like these, you should automatically assume that the temperature at the top is less than -20 C.

Usefulness of this information in everyday conversation, a module I call,  “Conversational Meteorology.”

The scene:  you’re walking/hiking with a friend on a warm morning when sunrise occurs.  You see these clouds.  The conversation has died off since you’ve been walking for several hours. You’re looking for something to say to re-energize the conversation.  Suddenly, you look up and see this scene below and blurt out, “Man, those clouds are cold!”  The volume of your blurtation has surprised even you, and startles your friend who was thinking about that tortoise on the trail ahead of you.  You rattle on about how cold the clouds with a followup, “Man, they must be at least colder than -20 C!”  Your friend seems puzzled at your excitement, but listens politely’ after all he is your friend.  You quickly add, “Almost every cloud has some snow coming out of it, no matter how small it is! Wow!”  Your friend, now saturated with your exuberances, asks if you saw the last episode of NCIS last night?

The end.

 

Altocumulus overhead; sunrise photo op coming

An upper level disturbance is going to pass over us today (see map with bend in the winds at 30,000 feet coming toward us here), but the only thing we’ll notice is some nice Altocumulus clouds floating over followed by a clearing later on today.  Those clouds are overhead now in the pre-dawn hours, we’ll likely have another one of those gaudy, too-colorful-to-be-believed-like-one-of-those-velvet-art-pieces-sold-on-street-corners-sunrises that we are known for here in AZ.  Might even have a little virga with them.   Lucky us!  So you should have your camera battery charged up in case this one’s really good!  You’ll want to add to your collection of 78,000 or so fabulous sunrises and sunsets in Catalina, AZ…like I will.

Note, too, that in this depiction of winds (the wind is flowing along the lines) that where the wind has a “U” shape, there are clouds to the east of those bends for the most part, that is, ahead of where that “U” shape in the winds is headed, and not much to its rearward, or in most cases, immediately to the west of the “U” bends in the winds.  We will see the “ahead” portion of a “U” in the winds above us, and the clearing that comes afterward, all today!

The end (for now).

 

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.

1)


“Stuck Inside of Tucson with the Seattle Blues Again”

Paraphrasing Bob Dylan’s song title, one that had the line, “Stuck inside of Mobile with the Memphis blues again”, that great, driving song he did in the 1960s.  See photos of Seattle-like conditions of low-based Nimbostratus below with a temperature of only  37 F (!) right now in Catalina!  Egad.   As you can also see, after 0.39 inches of rain up until about 11:30 AM this morning, there is also some flooding going on.

(Of course, me and most Arizonans really LOVE rain; it’s to be treasured at all times!  In Seattle, where I just spent three weeks, not so much.)

Local weather for Catalina here.

@

 

 

Some iridescence with your clouds? And a photo comparison of our current droughty conditions compared to last April’s green

Yes, we had some yesterday evening in those Altocumulus lenticularis clouds or just “clouds” for most of you.  This delicate “rainbow” coloring in last evening’s clouds is due to the diffraction of light around really small cloud droplets, ones that have just formed, a few microns to 1o microns or so in diameter.  Because the droplets have to be “really small” to produce this effect, iridescence is almost always located at the upwind edge of clouds that thicken downwind, as these do.  It was more colorful than I could photograph, but here are a couple of shots of that phenomenon we call cloud iridescence, or irisation:

By the way, the winds at cloud level here (around 2o -22 kft above the ground and at -30 C or so) were just about 100 mph (85 knots) at this time as that huge trough over southern California edges closer to us.  Unfortunately, it is “ejected” to the northeast out of southern Cal this morning and that means that this whole upper level system will be moving faster and faster as it moves toward Arizona and then into the Plains States.  That means that the band of rain generated with this system will be moving through at a faster pace and for that reason won’t produce as much rain as it might have if the system was not speeding up.  Still, looks like we should get, here in Catalinaland, around a quarter to half an inch.  Very exciting, since it will do what vegetation we have some good.

Free range grazing land now down to about just dirt, as little of the spring grasses have poked up before being ravaged by hungry cattle and native wildlife.  Kinda depressing after last spring’s bountiful display of grasses and wildflowers.  I have contrasting photos below as well.  You won’t like what you see in this comparison because it brings our droughty winter into sharp focus.   What is nice about our desert is that the mesquite and acacia bushes/ trees don’t seem to care how dry it is and are still are intensely green this time of the year, some consolation for the lack of green elsewhere.

You also may be struck by how tall I am, perhaps I played basketball in college you wonder.   In the first photo illustrating the dry conditions, I am apparently several feet taller than my wife, Judy, who walks ahead of me with Zuma, one of our dogs.  I guess I could have been on stilts, but I am actually on our horse, Jake, and am not that tall FYI.

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.

Exit right (or to the east)

Here’s what happened on top of us yesterday, that gorgeous snow day with so many wonderful sights to see. These maps below,  courtesy of San Francisco State University , for 500 millibar pressure level, about 18,000 feet above sea level, for 5 AM LST as the snow band moved through Catalina, and then 5PM LST,  a little before sunset:

 

 

A visual on what the clouds did as this happened yesterday is below. Interpretative cloud statements on the following gallery: shallow, deeper (precip begins in distance), deepest (small, soft hail falls here and there from miniature cumulonimbus clouds), less deep (barely-able-to-precip stage again), shallow, nil. Pics 1,2, 3, 4, 5, and 6, respectively.  If you want all the visual glory of yesterday, go to the U of A time lapse movie here.  However, you’d better hurry, these wonderful films are overwritten each day.  You can really see the clouds flatten out after about 3 PM LST here, and there are some spectacular snow showers going by on the Catalinas.

The end.

1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

“Smells like desert snow”

Seattle’s Curt Cobain might have said something like this if he had lived in the desert.   Alluding, of course, here to the SEATTLE teen angst band, Nirvana, and their big hit, “Smells Like Teen Spirit”. BTW, a song covered later by Bill Nye the Science Guy in an educational ditty,  “Smells Like Air Pressure”.  But why do this, have a title like this?  Contrived, ludicrous “cleverness.”  The world needs more honesty.

Began as a good rain at 2:40 AM, and by 4:20 AM, was changing to snow, for those detailed oriented folk.  Measured 2 inches on two locations here at 3200 feet, top of the car outside and on the “barbie” cover just as the snow was letting up around 6:30 AM.   Two minutes later, it would not have been as deep since all of the surfaces are above freezing in temperature and the snow depth lessens by the minute.  This was the third or fourth snowfall here in Catalina since we moved here in mid-2008, and was just that bit more than the “record” deepest of 1.5 inches in December 2008.

Here’s the SHARP FROPA, passage of the dramatic cold front “plus”) this morning at 3 AM as seen in the temperature and pressure records (software is a bit immature and won’t allow printing of two parameters on the same chart).  Note sharp rise in pressure at “FROPA”, the classic sign of a cold front’s passage.

La Nina-like conditions seem to return over the next couple of weeks, so lay back and enjoy the soil moisture while you can!  Some photos, the first something we Arizonans (of late)  called an “Arizona Christmas tree”, a snow covered cholla cactus.