Category Archives: Definitions

Catalina cloud drought ends with a whimper Sunday

In case you didn’t see it, here it is, a Cumulus fractus, a real whimper of a cloud. It had appeared in that same spot earlier in the day, before noon on Sunday.  Formed again in the afternoon.  It was pretty exciting, considering we have been absent  clouds for about two weeks it seems.    And this little tyke there, well beyond Charoleau Gap,  did indicate that the humidity here had increased on us as that unusually strong low center moved across the Great Basin and into  Colorado on Sunday.  Perhaps its hard to tell, but that was a “boundary layer” cloud, as any form of Cumulus cloud usually is.   That is, a cloud whose updraft has roots at the ground in this case.

Also, I have a new layer of topsoil in my yard now.   Thank you, 35-50 mph wind gusts on Sunday.   Go here to see the time lapse of a dusty afternoon in Tucson from the U of A.  The Catalinas are barely visible at 17:35 PM LST.

Since this ONE little shred of a cloud popped up in the same spot a couple of times, and also downwind of the Catalina mountains, it may represents a “bounce” in the airflow in the lee of the mountains, possibly a rotor type cloud–no pilot would/should go near this thing on SUCH a windy day!  Extreme turbulence can be observed below this cloud.  If you could see the airflow in a side view, it likely would have appeared like a huge breaking wave with the splash off the ground represented by that cloud.

The second photo is a cross section of another mountain, Mount Shasta in northern California that MIGHT illustrate what was happening on Sunday.  In this shot, a fairly laminar flow is breaking into something akin to a giant ocean wave, and the splash from that “wave” is giving rise to those ragged Cumulus clouds in the LEE of the mountain on the left of the photo.  The wind was blowing strongly from right to left.

So, our one little cloud may have been due to a breaking wave in the lee of the Catalinas, one that would have produced extremely turbulent air.

On Monday, we had just enough  leftovers after a dry cold front went through for this nice sunrise of Altocumulus clouds.  How nice!

Dear commentators…

Still floundering around here doing a blog, and have not been responsive to commentators, haven’t quite done much to improve the presentation here, either, and it needs it.  Many comments I’ve learned since starting up, are not “real” ones, but are advertisements for something.  That said, there ARE  many sincere ones that I have not responded to and I apologize for that rudeness, incivility, to someone who took some time to say something nice.    The “Comments” aspect of a blog was the most fearful part of even starting one;  “what if people actually read this and then said things?”  You might eventually have a career being responsive to those comments, sorting out the real ones from the disingenuous ones, and so forth.

So, I have not yet figured out what to do with comments.   While I will never attain the magnitude of a deeply admired friend’s sometimes controversial climate blog, one that was pummeled with more than 1000 (!) comments in 24 h after a controversial post, nevertheless there is time involved in doing “thoughtful” responses since I don’t write too good and have to go over drafts, a wife, two dogs and a horse to take care of, and am still a bit active professionally.

Mainly the goal of this blog is to pass along some knowledge gained over a lifetime of chasing clouds around, scrutinizing the sky, and in particular, that skill and knowledge gained with the University of Washington’s now defunct Cloud and Aerosol Research Group over about a 30 year period of “soft money” in airborne atudies of clouds.  After all, in a sense, you paid for it via the National Science Foundation, and I thought this blog would be a modest way of paying you back for all those grand years I enjoyed so much.  Below, a couple of shots of one of our more “interesting” maneuvers, gathering aerosol measurements over the surface of the (first, Atlantic, second, Pacific) oceans.  (“Don’t try this at home….”)  Will post a couple more shots a bit later.   The shots were taken between 50 and 150 feet above the surface of the ocean, a height that depended on conditions.  The 3rd shot below was taken from around 150 feet for obvious reasons.

During these many, many scraping-the-ocean’s-surface maneuvers, I made the same comment to the pilot every time:  “Hey, Steve, I just saw a jelly fish….and the jelly fish had a gnat on it.”

The last one?  Had a 16×20 of this shot framed.  At the Seattle gallery where this was done, the person doing it asked,”Oh, did you take this from your boat?”   It was so funny.  It was taken from behind the pilot looking through his window.

Also, and I think its genetic, there is a tendency for goofy (sophomoric?) humor amid the serious commentaries here.

I’ve always tended toward humor as do other members of my family.   I got kicked out of Jr. High classes after puberty due to a lot wisecracks, or actions like riccochetting rubber bands off the ceiling so that they would pile up next to the guy in my class most likely to use them in a more direct manner after he noticed them.  Underlying cause, first principal for humor: there is no greater moment in human relations than creating a laugh or just a smile.

Of course, all of that Jr. High goofiness was REALLY all about girls in those days since I had been a model student, got lots of “A’s” before puberty.   But it was all downhill after that, though a WONDERFUL, EXHILARATING discovery and academic cascade due  to  those marvelously different beings called, “GIRLS!” through Jr. H, HS a I drew attention to myself in unfavorable ways since I was too shy to actually talk to them…  Oops, way off track.

Mainly, thanks for taking time to “comment”!

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.

De-constructing a sprinkle, its THAT dry here…

and that’s what we’re down to.

Today’s topic will be a chapter in the strangely believe it book.  This is about literally about three or four drops at most that hit me at 5:18 PM LST while outside photographing clouds (of course!).   I really didn’t think they  were drops from clouds, I could not see a darn thing that could have done this overhead or downwind, I mean zilch, nada, nil zero, in my esteemed estimation.  I cast them off as something due to a misuse of water by my neighbor.  Definitely, it had to be some pseudo-sprinkle.   Just to be sure, I looked on the top of an iron fence, and there were exactly two drops.  Wow, I thought, could drops really have fallen out of the sky with virtually no cloud???  And more technically, no indication whatsoever of ice in those small Cumulus?  One more check, the dusty car.    It was dumbfounded to see that there was a smattering of small drops there as well!  How could this be?  It was the Twilight Zone for me.

Here is the sky about 10 minutes before (1), one minute before (2) five minutes after (3), and (4) comprises an “explanation”; extremely thin veils of ice crystals can clearly (he sez) be seen below the tiny cumulus clouds.  Perhaps there were just too few ice crystals in those approaching clouds, and those downwind to see any frizzy bottoms due to virga in #3.  I sure couldn’t see it, nor really did I see any ice elsewhere except far to the northwest to north later in the afternoon.

So how cold was it at cloud top?   If you’re really into clouds and stuff, you’ll want to know, of course.

Well, there was a sounding released around 3:30 PM or so in the afternoon for the 0000 Z (Greenwich) time sounding from Tucson.  The tops it indicated were but -10 C.  I will now purport that that temperature is incorrect for the clouds that passed over me and are those tiny Cumulus shown in #4.  Can’t happen with -10 C tops on THIS kind of day.  So I reject that sounding as applicable to MY clouds!  (Hmmm, nice RW- right now at 5:42 AM, yay, might even darken the pavement!)  So what is the best explanation for ice in small clouds?  Probably the air got slightly colder after the sounding was released, but that probably would not account for too much change, but something in the right direction of colder tops than -10 C.  I would say that more important was the stunning drop in temperature aloft as you go north from Tucson being the best explanatory “culprit”.  That is, it was significantly colder of us here in Catalina that it was where that sounding balloon went up.   Being colder aloft would allow the tops to be a bit higher and colder, as well as being cooler just because they were to the north of the sounding.  Flummoxed by this dizzying explanation?  I hope not.  In sum, those kinds of small clouds that produce ice were probably colder at top than about -12 C, and so we’re not talking a lot.

Summary:  Colder to the north, cloud tops were a bit higher, too.  Result, ICE (required for rain nearly always in AZ)!

Just recorded 0.o1 inches here at 5:52 AM!  Yes, Virginia, it CAN rain in SE Arizona!

Now about dust….  Dust has been implicated as helping clouds to rain, particularly in desert environments (sweet!  What an amazing thing that is, the desert soil having particles that help the clouds overhead to precipitate.  Unbelievable.

There is something to that.  In the olden days of the 1970s during the Colorado River Basin Pilot Project, a huge randomized cloud seeding experiment, the highest values of ice nuclei measured on the ground, anyway, was in a dust storm!  Also, in the 1990s,  it was hypostulated that dust from regions upwind of Israel helped clouds to rain on the southern margins of storms where dust was more likely to be encountered.  Finally, during a field project in Saudi Arabia a few years ago, I also experienced an effect of a large particle dust episode on Stratocumulus clouds first hand.  Surprisingly shallow Sc clouds contained drizzle drops and later, ice at high cloud top temperatures, higher than -10 C.  The characteristic of these dust particles, apparently, was to produce a broad droplet spectrum below the freezing level  (one that extends the droplet sizes past 30 um in diameter) and that in turn, accelerate the formation of ice and snow, which melts into rain.  Also, it may be, too, that the dust particles are active as ice nuclei at high temperatures, science speak for triggering the formation of ice at temperatures warmer than about -12 C.

The point of this is that it is POSSIBLE that dust contributed yesterday to ice in shallow clouds, too.

The end

The Twelve…rain drops in Catalina, that is

Well, maybe there were about 27, but anyway….not very many; still,  those drops were to be treasured after not seeing a single  “hydrometeor” display in SE AZ in so–ooooo LONG A TIME!


PG-13 advisory; DRIZZLE is discussed

I have to warn you at this point.  That rain event yesterday WAS NOT DRIZZLE!!!!!!!!!!!!!!!!!!!!!!!!!!!  I will be ROYALLY PO-ed if I hear someone in my social network or a TEEVEE weather presenter say that it “drizzled” yesterday!

Why make a BIG THING out of the correct type of precipitation?

I have to tell you a true story (well, I don’t have to, but I am going to anyway) about the importance of drizzle (i. e., fine, close together drops that appear to FLOAT in the air).   This event happened during my cloud seeding “vigilante” adventures (see Publications for samples).   A well-known professor of cloud seeding in a foreign country asked me to leave his office and never come back after I told him it had been “drizzling” outside, “10s per liter” in the air.

Drizzle is a profound indicator of cloud structure overhead, and the presence of drizzle falling from the clouds in that professor’s region’s meant his numerous reports of how clouds were, ripe for cloud seeding,  were in substantial error.   So you can understand why a report of true “drizzle” would naturally be upsetting to that professor.  Man, am I digressing here!  Yikes.  My apologies. (BTW, those reports WERE in error, confirmed by aircraft years later!   (Spiking football now, with a proper amount of decorum, of course!)


OK, back on task….

With the sky full of low (“boundary layer”) clouds by mid-day (f you’ve forgotten, that was yesterday, May 10th, 2011) and with RW— in the air  (“triple minus”, extremely light rain showers) by 1:30 PM,  with gusty winds,  temperatures in the mid-60s, it turned out to be quite a “storm.”  It just as well could have been but a mostly sunny day with just a scattered Cumulus clouds here and there the way some models were “telling it.”

Here’s a pictorial on how it went, from a Catalina, AZ, perspective:

1) 09:29 AM, itty bitty Cumulus (Cumulus “fractus”) starting to appear,

2) 12:03 PM, larger Cumulus growing up into Cumulus “mediocris” beyond Tortolita Mountains on the horizon,

3) 12:29 PM, virga and rain visible to the NW horizon!  Now I am getting apoplectic since the best models in the world did not have this precipitation over thataway!   But there it is, bigger than watermelons.  The models have to be really red-faced about this! Not everything in the world is predetermined by numerical models; you can  say things that might be right and those models are WRONG!  Just like in the 1970s when a lot people thought global cooling was underway and that’s where we were headed!  But they were WRONG!  Who were those clowns anyway?! (hahaha, sort of).

4) 1:25 PM.  Now where was I before all that excitement?  Oh, yeah.  Here’s some ice for you.  See the frizzy top parts of this cloud in the center of this photo above the dead tree that the birds like to sit in?  Well, them’s ice crystals, and likely snowflakes that have formed in that medium-sized Cumulus cloud (above the dead tree) and its in the upwind direction.  Behind that is more ice and precip falling from a wide area of a Cumulus-Stratocumulus complex.



Quiz.  How cold does the top of THAT cloud have to be to look like that (have that much ice in it, probably a few per liter to maybe 10 or so, not a tremendous amount but significant)?  Well, with bases as cold as they were, near freezing by this time of day at around 7, 000 feet above the ground or 10, 000 feet above sea level, around -15 C (or about 5 F).  Amaze your friends with cloud trivia like this!  Well, maybe not.


5)  1:25 PM.  Here it is, a band of precipitating clouds overhead.  Now the ONLY question remaining, as you gaze upwind at Twin Peaks clearly visible through the precip and virga is, how much will there be?  None? Or as much as a “trace”?   Measurable is out of the question,  looking at this scene below the clouds.  Most of the visibility degradation is due to dusty air, not precip.  Darn.   (Amaze your friends with skills like this!  Well, maybe not.)

6) 3:03 PM.   The End is Near

7) 7:06 PM.  Nice sunset with traces of Cirrus and Ac len on the horizon, driblets from a storm striking the Pac NW.  Isn’t there always a storm striking the Pac NW? I digress again.

Man, I could go on about the weather maps of yesterday, but will quit here.

The end.






















































If you REALLY want to see how it went, take a look at the U of A time lapse video here.

“Oh so pretty….”

You know the rest of the words to this song, the punch line,  “…pretty ugly.”  Yes, who can forget Johnny Rotten….?

Gorgeous clouds yesterday, but no rain is going to follow them (the “ugly” part)!  I had really hoped for a splotch of glaciating Stratocumulus clouds this morning after the great display of….the tongue twister, Altocumulus (Ac) perlucidus undulatus, a mid-level cloud with a honey-comb of elements (“perlucidus”), and those elements also aligned in rows (“undulatus”).  If you looked off toward Twin Peaks, you saw that the the back edge to these clouds was very smooth looking and did not advance toward us.  That was an Ac lenticularis cloud that started the whole shebang.  That lenticular cloud, as often happens, devolved into little cloudlets and rows;  its smooth lenticular form devolving into cloudlets that trailed downwind over us here in Catalina.    See pretty pictures below. One has the crescent moon in it.


Now it looks “pretty ugly” here for rain since there are no clouds this AM!   “Dang”, as a friend would say.

Why get excited about the chance of a sprinkle, or at least some pretty virga this morning because of the two layers of clouds yesterday afternoon?   No model indicated any rain.  First, it doesn’t happen often, but to HELL with models, they can be WRONG.  Don’t bet against them too often, though.  You will lose everything.

So, if you were just eye-balling the movement of those two cloud layers later yesterday afternoon and using the crescent moon as your fix, you saw that those mid-level Ac clouds were jetting along at a tremendous speed as they passed it.

How fast?

The NWS balloon sounding indicated that at the height of those pretty Ac clouds, about 20,000 feet above ground level, they were blowing along at no less than 80-90 mph (70-75 knots)!   This is a really strong jet for May!  And it indicated that the jet stream must be right over us, or darn close, and it was blowing from the SW.  If you no doubt know,  Buys-Ballots Law, in the northern hemisphere means that a low or trough is to the west of you, and in this case;  above you, not at ground level since you’re looking at higher clouds.

Also, the small Cumulus were beginning to cluster into Stratocumulus over the Catalina Mountains.  Getting pumped because there movement was showing more southerly now; the wind was more southerly at that level than it had been in the morning, also suggesting the influence of the trough to the west.   Here they are.  If you really want to relive yesterday’s clouds, particular in the afternoon and evening, our friends at the U of Arizona Wildcat Department of Atmospheric Meteorology have captured them

here.  For the really sharpies who DO go here, you’ll see that these cloudlets were further devolving in this time lapse to “ghosts” of their former droplet selves in the form of barely visible, icy little veils as they exit the area.  So, can you guess the temperature of those clouds?  Piece a cake:  probably -20 C or less (-4 F or less).  Sounding indicates -20 C, BTW.

Perhaps, I mused yesterday afternoon in a bout of wishful thinking,  that in the core of that trough heading for us, there’ll be a smidgeon of Pacific moisture left within its interior, enough for some thicker lower clouds than now, and those clouds will be cold enough, too, so that they will form ice inside them and we’ll see some virga (trails of snow fall out of them) or get a sprinkle (in spite of what the models were saying)!  Many of you will remember that according to Willis and Rangno (1971–Final Report to the Bureau of Reclamation by EG&G, Inc) that rain can only fall in the wintertime here when you are in the interior of a trough.  I’m sure many of you have this report, and can look it up jf you don’t remember.

Well, we should still see a few isolated Cumulus around, small ones, maybe as big as “mediocris” stage (1 km thick or so, 3300 feet).  And, with the coldest air over us this afternoon and evening, I am going to stick with an expectation of some ice in those clouds!  And you will here about it tomorrow if there is one crystal up there!

Finally, for cloud technicians, how cold will it have to get at cloud top to have ice in those small clouds around here in Arizona today?  Well, between about -10  and -15 C (14 to 5 F)–this is somewhat higher than for those mid-level clouds.  So we will check that out tomorrow, too!


“The end”, unless I think of something else later.


Footnote:  It now appears that last night’s model run of the “Beowulf Cluster” at the U of A has some precip on the Catalinas, between 3-4 PM LST today.  Interesting that after I had this thought based on a crude conceptual model, that the “Cluster” would now have that thought as well….  Hmmmm.

Climate change: what they were saying, 1974

An early anticipation of a possible climate castastrophy

One of the great books of our time on weather modification and climate change came out in 1974:  Weather and Climate Modification by Wiley-Interscience Press. It was edited by Wilmot N. Hess, Director of the Environmental Research Labs under NOAA.   Hess oversaw 11 ERL programs.   The contributors to this book read like a who’s who of those fields back then.   The discussion of climate and climate change in this volume involves Joseph Smagorinsky on Global Atmospheric Modeling and the Numerical Simulation of Climate, Les Machta and  K. Telegadas on Inadvertent Large Scale Weather Modification, and Helmut Landsberg on Inadvertent Atmospheric Modification through Urbanization–the heat island phenomena.  The book was reviewed by numerous equally outstanding scientists of that era, some of whom are still active today.  In re-reading this volume, meant to bring a sophisticated lay audience up to date on progress in these fields in 1974, I came across this introduction to Section F on global climate, likely written by Hess,  p631-632.  Please pay particular attention to the phrase below, “..the majority of participants…” at the end of the first paragraph.

I only point this out because there has been a bit of an attempt to “re-write history” regarding what our best scientists were thinking in those days when the earth’s temperature was in decline, one that began around 1940 or so, a decline that continued into the 1970s with no explanation and counter to increases in CO2 concentrations of those days.  Much WAS published concerning CO2 and about its global warming affect, but it wasn’t being observed.  Mostly, it was just EASY to perturb the atmosphere in the crude models with something like CO2 with its well-known radiative attributes, hence, maybe get a publication.   However, not much else was known about what perturbed the exceedingly complex global climate system and caused the modest temperature meanderings, such as those shown in the third insert.

Yes, its true.   Back then (late 60s into the 70s) we were starting to think about global cooling in a visceral way based on obs.

When I say, “we”,  I am not referring to myself; I was merely a forecaster-meteorologist with in a large randomized cloud seeding experiment in those days in Durango, Colorado.  Weather and Climate Modification was important to me in the years after 1974 because of the sections on cloud seeding, not because of the climate change discussion here which I have re-discovered.  (Please excuse the highlighting, done decades ago.)

Below (third insert) is the northern and southern hemisphere’s mean temperature record as deduced by NOAA’s J. Murray Mitchell in those days; these charts appear on  p719 of this volume, and were well known at the time.  Its easy to see from these graphs why there was so much concern about global cooling in those days when you look at the decline in both hemispheric temperatures after 1940.


Another bit of interest today is the essay by Machta and Telegadas (Chapter 19, p687) in this book.  Their essay concludes with a summary by H. H. Lamb  (a well-known East Anglia University climate researcher) that contains predictions of NATURAL (emphasized by the present writer)  climatic changes and a brief evaluation of those predictions.

What was particularly remarkable was the evaluation, apparently by Lamb, in the section, “Actual Forecasts“.   In this section, seven attempts to forecast the future climate from periodicities deduced in past data are briefly evaluated.   In today’s lingo, some of these efforts might be called early detections of pressure “oscillations”, that is,  shifts in modes of circulation patterns, where high and low pressures like to reside (footnote).  These “actual forecasts”, ones that appeared in the journal literature, were based on such parameters as changes in circulation patterns deduced over decades, patterns in oxygen and hydrogen isotope ratios in ice cores that were then subject to Fourier analysis,  climate forecasts based on projected sunspot activity, another on particle radiation from expected solar flares, patterns of “meridionality” or, north and south components in the wind, and “local” circulation patterns over Europe, and that latter in a paper published in 1939!  And, of course, the old standby,  tree ring patterns, again looking for harmonics or cycles in those data.   Most of this kind work, deducing cycles in past data in the way that it was done in these papers would be taken with a grain of salt, or not taken seriously at all.

SO, WHY even mention these studies?

Lamb finds most of the predictions were CORRECT in anticipating the colder weather ahead over coming decades after these studies were published!  Its really stupefying to read this section today and see an assessment of “correct” assigned to these forecasts based on no real underlying physical mechanism, such as why did the wind, the pressure pattern change, or on sunspots?  (It was interesting to note that the sunspot based forecast was deemed “correct” for weather, but totally wrong on sunspot activity!)

Well, it does make one wonder how these forecasts could have been correct.  Were a few researchers on to something that we have missed, or have also “re-discovered”, framing our findings today in more sophisticated terms such as “oscillations” instead of “cycles”?

Or were these forecasts “correct” because they were the only ones of hundreds of such forecasts (in which it would be expected that a few would be “correct” just by chance)?   The authors of this Chapter 19 do not divulge how many forecasts were examined.

However, those early forecasts based on circulation pattern changes over decades, should grab the attention of today’s “oscillators” if they haven’t already.


Footnote:  It sometimes seems as though almost every climate researcher today has his own personal “oscillation”, from the Pacific Decadal Oscillation, North Atlantic Oscillation, Arctic Oscillation, Southern Oscillation, on and on.  More will be reported.  (Maybe I should have one!)  ((Actually, I do have my own climate oscillation, but its not been published, probably never will be.))


































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.