Category: Cumulus clouds

Sprinkles! (coded as “RW- -” if you are keeping a weather diary!) (Its not drizzle!)

Pretty excited up there, as usual.

The Cumulus and Stratocumulus clouds began filling in yesterday, and some shed ice/snow virga in the late afternoon.  With that a few drops of rain (melted snow, of course) plopped down on Catalina.  In case you missed those drops, here they are.

Also, here are a few shots of those clouds, ones based about 7,000 feet above us, judging from their height above Mt. Sara Lemmon.

Note the trails of virga dropping out of Stratocumulus clouds near and over the Cat Mountains in shots 3 and 4.  That was the “worst” of our “storm”  right then when the clouds got their deepest, which wasn’t all that deep, maybe 3,000 feet or 1 km.

By now, too, you will know instantly that the top temperatures of those clouds, to be able to produce ice, were lower than -10 C (14 F).  This kind of knowledge about local clouds and ice, is also a great “ice breaker” at parties and barbecues.  In fact, the TUS sounding suggests that the general top was about -12 to -13 C, with likely momentary tops protruding to -15 C or so.  This would suggest marginal ice formation in clouds with bases as cold as ours were, about -7 to -8 C (about 18 F).  (Strangely Believe It:  warmer cloud bases with the same top temperatures as we had yesterday, leads to more ice formation, and precip.)

Below the photos is the mid-level weather map for the time the sprinkles occurred from the University of Washington.  Since the wind follows the green contours on this map, you can see two things.  The wind maximum at this level (500 millibars) is south of us over northern Mexico, and that the wind was on the verge of shifting to the WNW above us at map time (5 PM AST yesterday).   That wind shift line is referred to as a trough, and at, and ahead of the wind shift line, clouds and precip are stimulated, while behind it, the air gets drier and clouds are mashed down or disappear.  You could even see that happening to the west of us yesterday afternoon while the clouds were heavy and precipitating over the Catalinas.  Those clouds over the mountains, too began to whither, and the virga ended, not JUST because it was heading toward evening and getting cooler, but also because of that trough was passing to the east at that time and the drier, descending air was moving in over us.

In this map, you will also see the much stronger trough over northern California, one that is racing toward us and will bring rain as early as tomorrow morning!  Yay!  However, the U of AZ massive Beowulf Weather Calculating Computer Cluster foretells only about a tenth of an inch from this next storm (here).  Boo!   I will suggest that might be a little on the light side, but that’s because I am biased and strongly want more rain than a tenth from this new storm; I’ll venture 0.25 inches or so here in Catalinaland by Wednesday morning.

More storms after this next one?  Oh, yeah!

The End

Story time: They said they couldn’t exist, but we found some anyway (extra giant raindrops)


While waiting for the chance of rain mid-week next week, I thought I would tell another science story…

How me and Doc Hobbs got into the Guinness Book of World Records

Rain drops bigger than about 5 mm in diameter (only about 0.2 inches) are thought, mainly through lab experiments, to break up into smaller drops before they reach sizes larger than that.   Also, they had not been reported to reach sizes larger than that until the mid-1980s when researchers sampling modest Cumulus congestus clouds topping out at only around 14,000 feet around the Hawiaan Islands reported intercepting drops that were 4-8 mm in diameter.  This was pretty big news.

Later, while flying with the University of Washington’s research aircraft we intercepted (imaged with aircraft laser probes) drops that were 8.6 mm across and more likely as large as a centimeter, and not on one, but two different occasions separated by a few years.  These were larger than the ones reported by the Hawaiian researchers.  (Yes!!!! Spiking football now!!!)  

First, the award-certificate  for those who might be skeptical, and whose display is best part of today’s blog!  I mean, really, I could have put 257 worms in my mouth or that sort of tawdry thing, but this was much better, more digestible.  Oddly, neither Peter V. Hobbs, my co-author, and I know how we got this Guinness Certificate;  it just came in the mail sometime after our article,  Super-Large Raindrops appeared in the journal,  Geophysical Research Letters in 2004.  You know, it wasn’t that great of a “certificate” either.  I thought it would be on onion paper, or some other exclusive bond.  Instead, it was on something like a cheap, thin cardboard paper.  Still…….

The two instances of where these giant drops were encountered were in completely different, contrasting aerosol environments:  one in a clean, smog-free, oceanic environment near the equator in the Marshall Islands, and the other under a smoke-filled Cumulus congestus cloud in Rondonia, Brazil,  an area where there were many fires where the tropical forest was being burned away.  (We were in Brazil 1995 along with other research aircraft to study the nature and extent of the smoke being produced by those awful fires.)  Since any rain is thought to be hard to produce in smoky clouds that do not get to the Cumulonimbus stage, giant drops from them was news, too.  Of course,  many of you out there enjoy photographing images of raindrop splatters on various surfaces as kind of a hobby, particularly as  rain begins to fall.  Below, is an example from a friend of that sort who prefers to photograph those splatters as they occur on cement as an artform.  I think her work is in a local gallery…

So, knowing how much general interest there is out there  in rain for desert dwellers, which still might occur on Wednesday or Thursday, is the reason for today’s blog on huge raindrops.

Below is an example of what rain drops look like when they imaged by laser probes on the University of Washington’s research aircraft as we flew through those two instances of giant raindrops.  The images of the drops are the shadows of them.   As they pass under the wing of the aircraft, some go through a laser beam without being disturbed.   The laser shines on photosensitive diodes that get turned off and recorded when they are shadowed.  They stay off until the laser beam hits them again, thus recording the dimensions of whatever it was has passed by.    You then look at the diodes that were turned off for the tiny fraction of a second that something went through (for our aircraft, around 100 to 120 mph) and get an image of it that tells you whether it was a drop, ice crystal, snowflake, graupel, whatever.  Pretty amazing when you think about it.  You’ll have to click on it to really see anything.

The large red drops on the left side in the bottom rows are the partial images of the record setting drops.  The probe elements were not wide enough to see the whole drop.   On the right side is an ellipse fitting routine applied to the raindrop images we recorded that better displays the true size of partially viewed drops.  In this case, that algorithm suggested the very largest were about 1 cm (you can use that as a scale for the other ones), but because it is an estimate, does not count in the record books.   Only the actual measurized size was considered in the Guinness record.  The top two panels are from the Brazil encounter, and the bottom two panels are from the one near Kwajalein Atoll, Marshall Islands.

Here are some photos of the two areas we flew in so that you can see how different they were in character.  First, Kwajalein Atoll (note the gigantic runway, constructed in WWII, had its own cloud on calm days  !).  Second,  an example of a moderate-sized Cumulonimbus cloud, one similar in size or even a bit larger than the one Mr. Cloud-maven person himself was directing the University of Washington’s Convair-580 research aircraft into, targeting the heavier strands of rain that first falls from convective clouds.  It was so GORGEOUS there in Kwajalein!  I loved it there.  The skies, the sunsets!  Oh, my.

Kwajalein Atoll, BTW, is the terminus of the Vandenberg missle launches.  As yet another aside, on the TEEVEE there in Kwajalein, there were announcements in big red letters, like the ones for severe weather,  that told you when a missle had been launched at Kwakalein from Vandenberg, and when it was coming into the middle of the Atoll (you hoped!)  Folks would then gather on one of the Atoll beaches to watch the show.  It was so exciting!

As an aside, I have to tell you that one of the charms of that place, run by Raytheon, a name you are familiar with around here, was that you could not own a car, or house, or just about anything else, paid no taxes if you were a permanent employee, etc.  You had to have a bicycle for transportation for the most part.  It was like the atmosphere of a small (“communist”, hahaha) town (3500 lived and worked there).  Everyone went outside and walked or rode down the streets in the evenings.  Another charm was that the manager of the Kwajalein Missile Range site had hair down to his waist!  It was AMAZING!  Both he and his wife seemed to be in their late 30s with two little kids, and told me how much they loved it there!  Many others did, too.

Now on to the smoky environment in the State of Rodonia, Brazil, 1995, in the  “dry season”,  where the other giant drops were encountered.   Rodonia, at that time of year and in those days, was a pyromaniacs paradise.

First, the University of Washington’s research aircraft sitting on the runway in Porto Velho, Rodonia, Brazil.  By clicking on this image, and looking under the wing on the left, you can see the “Y” shaped probe that imaged the giant drops as they flew by.  Other images show the “Green Ocean” in smoke, and some ground shots that show how widespread fire was there.  In fact, after a couple of months there, we kind of got “into the culture” and wanted to burn some things up ourselves.  Check the fire along the highways!  No “Fire Danger is High” signs there!   I think its time to reprise Deep Purple’s “Smoke on the Water” (which is just about everywhere else in Brazil, anyway)  to get you in the mood for the shots to follow.  I will be jumping around now…  (Too bad Beethoven couldn’t write songs as good as this, but then he wasn’t that great with words….)  The last shot is a sunny day in Cuiaba, a large interior city of Brazil, during the burn season.

As an epilogue it should be pointed out that Brazil is making good progress in controlling the amount of burning compared to that which was going on in 1995.

 

 

 

 

 

 

 

 

 

 

Below is the region of “pyrocumulus congestus clouds (those due to fires below them) where the giant drops were encountered, near the city of Maraba, Brazil.  It was a little different than Kwaj!

 

The End (at last)

 


“(the reviewers)… are still unconvinced by these controversial claims.” A science story.

Alternate titles, choose one or all:

 1) The story of APIPs (Aircraft-Produced Ice Particles)

 2) They said it couldn’t be done, but they did it anyway

 3) ‘An embarrassment for the airborne research community’–Dr. John Hallett, 2008

OK, “baby I’m bored” with the lack of clouds and precip,  and so I thought I would share my boredom with this long tome on aircraft effects on clouds.  Why not bore other people if you’re bored?  I’ve thrown in some alternate titles above to peak and pique your interest.  Speaking of “thrown”,  Mr. Cloud-maven person was also thrown off his big (I mean huge1),  young horse lately; “JohnT”, as he is named, doesn’t like people to sit on top of him sometimes.  Not easy to sit at a computer these days, hence the lack of “acitvity.”

OK, on to the story of APIPs.  The title quote was written in 1982 by the Chief Editor of the American Meteorological Society’s, J. of Climate and Applied Meteorology (JCAM) summing up the opinions of the three reviewers at the bottom of a second rejection notice of a manuscript, one that had been fluffed up with more evidence of APIPs.   However, the Editor allowed us (me and Peter Hobbs, director of the Cloud and Aerosol Research Group at the University of Washington) another crack at it, and by the THIRD submission (requiring a bit of chutzpah),  a colleague and me had found photographic evidence of aircraft having produced icy canals in supercooled clouds, and that visual evidence really pushed our third manuscript, now as big as JohnT, over the top in getting accepted and  published.

The phenomenon came up again last summer in a Wall Street Journal article, one in which Mr. Cloud-maven person was asked his opinion.  This phenomenon (APIPs) is attracting more attention these days, so I thought I would pass this background story along.  I hope will encourage authors with rejected manuscripts, which I myself have quite a few.   You might have something really good.

Yes, that’s right, lucky Mr. Cloud-maven person was involved in this interesting chapter of science that happened way back in the early 1980s when he was part of the flight crew in the University of Washington’s Cloud and Aerosol Research Group (CARG).  Occasionally, and mostly in studies of ice development in Cumulus clouds, I got to direct the University of Washington’s first research aircraft, a 1939 manufactured, Douglas B-23, into Cumulus and small Cumulonimbus clouds.  It was heaven for me, a storm chaser type person, having done that here in AZ way back in the mid-1960s chasing summer thunderstorms all over the State with my camera and rain gauge.

We had a viewing dome on the top of the fuselage of that B-23 and I sat in a swivel chair, head protruding into the “bubble.”   I was kiddingly referred to as the “bubblehead.”  I think they were kidding, anyway…  Those who know me will understand that title.   Sitting there with head in the bubble, allowed me to see EXACTLY where we exited a cloud and could direct the pilot to EXACTLY that same cloud blob we had just exited.  The pilot was fond of turning the plane sidewise for this return so that one wing was pointed straight down in the turns and we often got back in within 90 s to two minutes.  It was an exciting as well as sickening experience.

We did that because we wanted to see how that element of the cloud had changed with time.  Did ice form?  Did the drops get bigger or smaller?

This viewing dome gave us a huge advantage over other research aircraft doing this kind of research.  Below, that B-23 aircraft sitting on the tarmac at Boeing Field, Seattle2.  The second photo is a view from the “bubble” located toward the rear of the fuselage.  Nice!  I was so lucky!

One day, while looking over our Brush strip charts from the flights, I noticed some odd spikes in the ice crystal detector we had. Also, since we were one of the first groups to get a probe that produced shadows of the particles in the clouds as we flew in them, I was able to see that the particles producing those spikes were oddly similar sized, as though they had formed simultaneously, something not seen so much in natural clouds. Pretty soon it became apparent that these spikes and odd particles ONLY appeared after we had gone through the same cloud for the second or third time.

I remember walking into Professor Peter Hobbs grand office with a strip chart with those ice spikes and saying, “I think our aircraft did this.”

He was unfazed; did not have a particular reaction.  Peter Hobbs was always open to new thoughts, and that helped allow me to go forward with a further investigation even if it meant some of our past data and publications might conceivably be compromised, ones however, I was not involved with as a fairly new (5-years in) employee at the U of WA.  No vested interests here!

After awhile, after aircraft plots showed that the spikes were within tens to a couple of hundred yards (meters) of where we had been before in a Cumulus cloud, a very short paper was written up on it and submitted to JCAM in late 1981.  It was quickly rejected.

Ours was a highly controversial finding due to both the high concentrations of ice that we found (hundreds  to over a 1,000 per liter) but most of all due to the temperatures at which we were reporting this effect, -8 to -12 C.   Our plane was,  in essence,  seeding these clouds with ice crystals, changing their structure.  Since the volume affected was initially quite small, it was likely that only having the viewing dome allowed us to find them on the second and third penetrations of the clouds.

This inadvertent aircraft effect had even been looked for by our aircraft group leader, Dr. Prof. Lawrence F. Radke before I had arrived and after the University of Washington acquired the B-23.  He didn’t find’em though.  Larry was also aware that an aircraft COULD do this in those early days with the B-23.

So, when I found them and a paper began taking shape, the skeptical Larry Radke called them,  “Art-PIPs.”  It was so funny.

Later, with the skeptical Larry at the helm, we got some money from the NSF to try to produce them in various clouds, and sure enough, we did.  It was amazing finding those crystals in those test flights since even I couldn’t be absolutely positive sure that this was real.  Why hadn’t this phenomenon been reported decades ago?   That, too, was part of our problem:  why you, why now?  And why hadn’t I seen the holes and canals of ice produced by aircraft as a cloud photographer for decades even by then?

Some ground observers had seen trails and holes in “supercooled” clouds like Altocumulus.   Those holes and canals were occasionally reported over the decades (!), but not in the technical journals.  A couple of really lucky observers had even seen the type of aircraft that had caused them.  But the airborone research community, ignored or did not know about these reports, ones that appeared in non-technical weather magazines like Weatherwise, Weather, and Meteorological Magazine (the latter two in England).

Furthermore temperature data were nearly always absent in these visual reports.  So, it could be reasoned they had occurred at very low temperatures, below -25 C or -30 C.  Clouds that cold, but still consisting of only or mostly of liquid droplets do occur, the ones in which an aircraft could leave an “ice canal” or a “hole” with ice in the center, falling slowly out.

If we had been reporting our finding at cloud temperatures of -25 to -30 C, maybe we’d have got into the journal on the first try and reviewers would have yawned.  But at -8 to -10 C cloud temperatures?  No way!

Why?

Research aircraft had been going back and sampling the same cloud, usually a Cumulus one,  for a couple of decades by the time of our report.   Furthermore, those aircraft re-penetrations were almost always in the same temperature domain that we were reporting this effect, to about -5 t0 about -15C.  And one of the main findings in those early days of aircraft sampling was that nature was producing far more ice in clouds than could be accounted for in measurements of ice nuclei, particles on which ice can form.  Concentrations of ice nuclei were largely determined from small cloud chamber measurements made on the ground.

These early cases of high ice concentrations in clouds with tops that were not very far below freezing (greater than -15 C) were called cases of “ice multiplication” or “ice enhancement.”   No one understood how such ice developed and many theories were put forward initially in the 1960s.  The issue was largely explained by the “Hallett-Mossop riming and splintering mechanism”, a mechanism discovered in the mid-1970s and today is still believed to be the primary reason for high concentrations of ice crystals in clouds with tops warmer than about -15 C.  Oh, yeah, ice multiplication is real and NOT due to aircraft penetrations!

But our paper on APIPs, if true and published,  would cause researchers to have to go back and look at their research data (even us!) and investigate whether their own aircraft had contaminated their published studies with artifact ice crystals.  An entire body of airborne literature would come under question.  This was not a pleasant thought for anyone who had  conducted such studies.

Why would you go back and sample the same cloud?

To see how it changed with time.   How many ice crystals formed as time went by?  Where, and when?  These were techniques used in trying to get to the bottom of the “ice multiplication” phenomenon.  In fact, the Chief Editor of JCAM himself was involved with numerous aircraft that sampled clouds in a huge summer Cumulus cloud study program in Montana in those days (called “CCOPE”-Cooperative Convective Precipitation Experiment)  That study, like so many other airborne studies, was to determine how ice onsets in clouds, how high the concentrations of natural crystals were in clouds with various cloud top temperatures, and the potential of cloud seeding to increase rain.

While academic scientists did not particularly welcome these reports and were dubious and largely ignored them (did not change their aircraft sampling strategies), or when they looked could hardly find any APIPs, it was soon evident that purveyors of cloud seeding services were elated!   Our finding suggested to THEM that all that natural ice formation reported in re-penetrated clouds  in research articles over the years might be wrong, and rather due to ice produce by the aircraft!  Maybe those clouds that had been reported with a lot of natural ice, which made them unsuitable for seeding, was because the researcher’s aircraft had produced it, not nature.  Purveyors of seeding would like clouds that are below freezing, about -5 C and colder, with no ice in them.  If the concentrations of natural ice crystals forming in clouds ice get to 10s to 100s per liter,  those clouds are deemed unsuitable for seeding to add more ice.  The crystals might be too small if you add more in those cases, and not fall out.  If surveys of clouds in a region find that they have lots of ice in them, its “no paycheck” for commercial cloud seeding interests. (Usually, cloud surveys aren’t done before commercial programs begin.)

Thus, those who had interests in cloud seeding actually saw our result as a way to discredit findings of high natural ice concentrations in clouds, findings that made them appear unsuitable for seeding.  It was a bogus argument since numerous FIRST penetrations of clouds had encountered high ice particle concentrations, still, they had SOMETHING to hang a hat on.

This was indeed an ironic twist, being supported by the cloud seeding community!

Me, usually with Peter Hobbs as a co-author, had been discrediting various published cloud seeding results in the literature via reanalyses and journal commentaries for several years (e.g., here) when our APIPs finding finally hit the “streets” in 1983.

Given these a a priori possible biases between academia and in the commercial cloud seeding world in detecting APIPs you can imagine where the major “confirmatory” studies of this phenomenon came from. Yep, those associated with cloud seeding programs!  It took 8 years (1991) for our finding to be independently confirmed (the best way) using several types of aircraft in marginally supercooled clouds.   Then pretty much the same workers amplified their findings with another paper in 2003 WOODLEY et al. 2003.  For those of you who don’t know the cloud seeding literature, Woodley and Rosenfeld and Peter and I have had a major clash in the cloud seeding literature (i. e. and big i. e., and bigger still)

We loved it!  They loved it!  Even the great John Hallett got involved and found in lab experiments that the mechanism was the extraoardinary cooling at the prop tips, momentarily down to -40 C, a temperature at which ice forms spontaneously in high concentrations (here).  It had also been suggested that prop aircraft could do this by the late Bernard Vonnegut back in the late 1940s in a less widely distributed report from a General Electric research lab and in the J. Applied Physics.

Today this phenomenon is taken pretty much for granted, and has been more widely detected from time to time in satellite imagery in thin clouds as here.  In thicker clouds, the effects of aircraft go largely undetected.  Recently, in a widely distributed news release that accompanied their formal publication, Heymsfield et al reported a case in Colorado in which aircraft-produced ice effected a snow shower on the ground instead of just being a hole or canal in some thin clouds as we normally see.  They opined that aircraft could actually help delay flights from the airports that they were taking off from or landing at in special conditions.  (That’s what the Wall Street Journal article was about.)

Why was it an “embarrassment” to the airborne research community, as John Hallett (of Hallett-Mossop) asserted?  Because they should have found out about APIPs right from the get go, especially in view of the occasional lay publications that had photographs of ice canals in supercooled clouds even in the 1940s, ones  that could only have been produced by aircraft.  It turned out to be a major oversight.

Below, a cartoon I did before the paper was accepted making fun of how a researcher, thinking that natural ice multiplication processes were taking place (i.e., the Hallett-Mossop riming splintering mechanism) might overlook all those ice crystals streaming off, in this case, the Husky 1 aircraft.

Below, some photographic evidence of what aircraft can do to supercooled clouds, the last one taken about two weeks ago over the Cat Mountains.

Finally!  The End.

 

 

 

 

 

 

 

 

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1The 6-year old horse in question is about 15 hands, 1200 lbs, not really a Clydesdale.  I have overemphasized our horse’s size for personal reasons.   You don’t want to be injured getting bucked off a Shetland pony, but rather something HUGE!  It just sounds better.

2That B-23 aircraft, wherever it went, brought a crowd out to see this antique “tail-dragger.”

The most interesting clouds–technical discussion ahead; skip now if you have a headache

Well, to me, anyway, those flat, thin ones yesterday (Stratocumulus, and Cumulus fractus, humilis, mediocris, if you want some names).  The thicker versions of these clouds were shedding ice and snow but weren’t very cold and that’s what made them interesting.  Take a look.  If your eye is calibrated you can see that light snow is falling on the Catalina Mountains in the first two photos, and in the third photo, one that better illustrates how thin these clouds were (probably 2,000 to 3,000 feet thick is all), snow is seen falling in the distance from the cloud above and to the right of the white roof of the shed in the foreground.  Quite remarkable.

Why?

According to our TUS sounding data, these clouds, at least at 5 AM LST, were topping out at only around -10 Celsius (14 F), a very marginal temperature for ice formation in clouds in Arizona.  By the afternoon, the TUS sounding was suggesting the clouds near the sounding balloon were as warm as -3 C (28 F), too warm for natural ice formation.  (Where the temperature and dewpoint temperature lines come together, right now, over me.)

If you go to the movies, the time lapse one from the U of AZ here, you will see that the clouds were coming toward TUS from the Catalina Mountains by the time of the afternoon sounding, and therefore its not valid for the heights of those clouds over the mountains–the air has sunk coming off them.  So, the best we can do is probably with the morning sounding and assume the clouds were topping out at the -10 C level with bases about 0 C to -2 C.  You can get base height from where they were intersecting the Catalina Mountains (the cloud, not the snow!).  That was at about 6,000 to 7,000 feet elevation, roughly 4,000 feet above ground level here in Catalina.

So, we had pretty cold bases, and not very cold tops.  When we see ice coming out of clouds like these (and I would estimate from airborne experience at the U of WA, that those concentrations of ice coming out of those clouds were a few to 10 per liter).  If that estimate is correct, then we would say that these clouds exhibited “ice multiplication” or “ice enhancement.”  That’s because we don’t expect concentrations that high in clouds with tops around -10 C.  That is,  unless something “extra” is going on to add to the very few ice crystals that might have formed without “multiplication”; perhaps only 1 in 100 liters at -10 C.

So wha happened?

Our most accepted theory is that the very few lead to the many in collisions with cloud drops.  Those cloud drops, when a bit larger than usual (24 microns in diameter for a number), shed ice splinters, and those splinters go on to populate the cloud.  It takes a long time because the itty bitty splinters have to grow to sizes where they can collide with cloud drops, too.  This ice enhancing mechanism, referred to the Hallet-Mossop riming splintering mechanism, named after two scientists named Hallett and Mossop (hahaha), is known to only occur in the temperature range of -2.5 C to -8 C.

Those temperatures were indeed found in our little clouds.  So, too much ice explained!

Not quite.

In little, cold-based clouds deep into the continent as we are here in Arizona, it would NOT be expected that the droplets inside those thin clouds would be large enough (as big as 24 microns in diameter) so that ice splinters would occur when colliding with the rare ice crystal, the 1 in 100 liters one.

So, that’s the mystery of yesterday.   These clouds DID look kind of “maritime” to me.  In maritime clouds, such as those found in onshore flow along our coasts, drops reach that critical size for riming and splintering just above the bottom of the cloud.  That’s because the air is clean over the ocean as a rule,  and so there are few particles for the moisture to condense on, leading to larger drops right away, and many fewer in a liter than in continental clouds.   A typical maritime cloud has less than 100,ooo drops per liter, whereas a “continental” cloud would have several hundred to a half a million drops per liter and even more in some polluted areas.  So, as a drop, its hard to be a big deal in a “continental” crowd like THAT!

Best thought is that the heavy rains of late cleaned the air hereabouts and those clouds that looked soft and “maritimey” yesterday REALLY were like maritime clouds found over the oceans away from land.  Maritime clouds, as ours might have been,  have large drops in them, and even drizzle and raindrops before reaching the freezing level.  Therefore,  ice forms in maritime clouds at the highest known temperatures for natural ice formation, -4 C to -7 C.

The End.  You might want to rest for awhile if you got this far.

The weather ahead?  More rain, continued below normal temperatures as another “cut off” low rolls off the jet stream table in the north Pacific and falls into the Southwest and Baja area in the next coupla days.


An icy 0.06 inches Catalina dessert

Like most people, I like dessert, especially if its precip in the desert.  Yesterday’s “graupelly” fall of little ice ball showers weren’t expected, a surprise entree.  Even the local model run by the U of AZ weather department on their “Beowulf Cluster” of computers had the showers staying to the north.  So as a weatherperson, you would go with those models; “hey”, they’re the best we can do.  That’s what the TEEVEE weather guys do, too, unless they are really great and can tweak and improve them by knowing the kinds of errors the models make.

A side light:   A professor of weather at the University of Washington recently gave a big lecture about how it is useless for the National Weather Service to try and beat the computer models for tomorrow’s and beyond weather.  As in the humorous take on that old spoken word, how-to-live song, Desiderata,  “Deteriorata”, by the Fire Sign Theatre back in the 70s, this professor told the NWS to, “Give up”;  devote your time to getting the first day right, among other things.  The computers have a tough time in the first 6-12 h, as we saw yesterday.

Yesterday, you could see  the “errors” developing right off the bat.  All of the billions and billions and billions of calculations by the models, to say something Carl Sagan, the astronomer-cosmologist might say if he had been a weatherman, were unraveling; going wrong, incorrect, getting an “F” for rain/snow prediction.    It was going to be a bad day for the computers, who, as we know, generally know more than we do, especially about us and the things we do and buy.

Yesterday, the first exciting hint for me that the showers might reach here rather than just be a little to the north as the models said, was this scene whilst out with the dogs around first light, 7:30 AM.  Look at that shower going by the Charleau Gap!  I thought I might see lightning!  But then I usually think I am going to see more in weather, and in other areas of life, that I want to have happen than actually happens.  I thought, for example, that the Washington Huskies would beat the woeful Oregon State Beavers in football.   Actually fairly confident there.  But, “no”, it didn’t happen.

Back to weather:  the proper weather person would have exclaimed when seeing showers to the left and to the right early yesterday morning (and popping out on the TUS radar) as I did, “Wow”, these clouds have ice in’em!  And that wasn’t supposed to happen!”

So this was the first sign that we had a good chance of showers/snow yesterday.  It was a truly great moment because the computers are so often correct.

But yesterday, they were going down!  Cumulus congestus/weak Cumulonimbus clouds everywhere!

I felt great.  When weather computers fail on the dry side, it makes me feel better as a human.   And  of course, seeing these shafts of precip, you could opine knowledgeably to you friends that the cloud tops are likely colder than -10 C (4 F) (since ice formation in clouds before that temperature is reached would be unlikely here in AZ).

Here are some additional shots from that glorious day yesterday, including, for Oregon State fans (“hey”, the former company team is going to a bowl game!) a closeup of “graupel” for your viewing pleasure.  The last shot is when subsiding air arrived and squashed the Cumulus down over the beautiful Catalina Mountains into “humilis” versions late in the afternoon.

The weather ahead?  A strong storm still shows up in about a week.

The End, except for trying to get this layout right!

 

Cumulus with Stratocumulus; hold the ice

Mr. Cloud-maven person hasn’t said much about clouds lately, which is kind of ironic since he deems himself a “cloud maven” and not much more.  Rather, he has been obsessing about POSSIBLE storms in AZ 15 days away which is kind of futile anyway.

So, as an excuse to show more cloud photos from that gorgeous day of snow and cloud shadows on the Catalinas yesterday, will go into a cloud lecture, a post-mortem so to speak.   Here are some cloud shots from yesterday, most below the one at left.  Note, not one cloud shows any virga yesterday, and some of them got, at least moderately humped up.  A promiscuous cloud maven person might have called one or two of the cumulus clouds, a “Cumulus congestus” (though they would be WRONG).  Well, maybe not that wrong–see the 1987 World Meteorological Organization International Cloud Atlas that I can’t stand because they goofed up on their cloud designations as you will see if you could only find one of those yourself.  Still kind of bummed out by that atlas, but one member of that cloud selecting panel told me they were too busy in their Paris meeting going to the Eiffel Tower and such rather than paying attention to getting the cloud photos they had properly named.   Now, where was I?

Right, I was talking about yesterday’s clouds….   Well, here are some cloud shots, ones that I was going to post 15 minutes ago before getting upset again over the 1987 WMO cloud atlas.  (Really, I could have done a better job than the WMO all by myself; it was a real boondoggle, that meeting of “cloud experts”, yeah right.)   OK, photos!

Now looking at ALL of these, you see no fibrous material falling out, even though some of the clouds look pretty dark in these perty scenes.   I was so happy to be alive and live here yesterday, feeling very, very lucky.  So, remembering the University that Bullwinkle Moose went to play football as the “Frostbite Flash”, “Whatsamatta U.”, we might say the same thing to these clouds, “Whatsamatta U?”   How’s come there no precip falling out, and those who read this silly site will answer immediately, “Them clouds ain’t got no ice in’em”, which would be correct.

But why?  It was awfully cold yesterday, and even Mr. Cloud-maven person, who does not even have the Master’s Degree, was wondering.  So, off to the TUS “99 Luftballoons” sounding data for yesterday afternoon, posted by our great U of A Weather Department below (where the lines come together are where the clouds were located).  Didn’t seem possible to me, but those cloud tops were hardly as cold as -5 C (23 F).  Ice does not form in clouds, even though they are below freezing, at this temperature in the natural state except in very special circumstances.  Ice formation in clouds, still not WELL understood, is known to be a function of drop sizes AND temperatures.   Over the oceans where cloud drop sizes are large,  it happens.  Usually, someone can get a whole scientific paper out of a cloud that formed natural ice when the top has never been colder than -4 C!

Here in Arizona, what we would call a continental cloud forming environment.   Cloud drops “is” smaller because there are so many more particles for the drops to condense on, and so the concentration of drops is higher, meaning the drops have to be smaller to condense out the same amount of water as over the oceans where the air has fewer particles for clouds to form on.   In a nice cumulus off the Washington coast of the sizes we had here yesterday, the cloud drops would be as large as half the diameter of a human hair (“wow”, huge, he sez, 30-50 microns in diameter, for the sake of a number) here in AZ in those clouds yesterday would be lucky to have drops in them as big as 20-25 microns, too small to activate ice forming processes, known to be related to drop sizes.   Oddly, the bigger the cloud drops, the HIGHER the temperature at which ice forms, especially if drizzle drops have formed.  The drops in our clouds yesterday were too small to have an appreciable fall speed, so they don’t fall out either.

Since I have published a lot of critical work on cloud seeding, one might ask if these clouds could have been made to snow by artificial means?   Even as a long time critic, the answer is an unambiguous “yes.”   With a small plane, and a little dry ice, you could have made a little snow fall out of these clouds because the tops were cold enough for that.  Dry ice, the substance you would have used,  has a temperature of -78 C, and when pellets falling, they leave a jillion ice crystals in their path as they cool the air momentarily to -40 C and below, the spontaneous nucleation temperature.  And, with ice in these clouds, the drops would be evaporating and the water molecules depositing themselves on the ice crystals.   Ice crystals in clouds of water drops are like little low pressure centers; the water molecules leave the drops and goes to ice, and ice crystal gets big enough to fall out.  Our natural precip here is like this most of the time.

So, summing up this little cloud-ice lesson, our clouds did not get cold enough, and at the temperature the tops DID get to, the drops weren’t big enough to trigger natural freezing.  Tell your friends.

The End.

“…goin’ down in the first round”

As Muhammad Ali might say, referring to the Climate Prediction Center’s three month outlook that was for dry conditions in Arizona from November to January.  So, the first round, November into early December, has delivered quite a punch against drought with another 0.40 inches here in Catalina last night.  Our December total is already 0.82 inches!  Rains have been bountiful, too, during this period in some parts of NM and Texas, horribly stricken with drought, so its been great run of drought smashing weather.   Check the latest 30 day US precip totals here (does not include the heavy rains of yesterday in TX, however).   And from WSI Intellicast, this 7 day total precip map.   Excellent.    In Catalina we now have had 2.63 inches since the beginning of November.

Below, the CPC forecast for November through January for the US issued last October 20th.  These predictions are weighted by the “moderate” La Nina event now going on in the central and eastern Pacific.  A La Nina leads to greater chances of dry conditions throughout most of the southern US.  Hence,  this forecast.  However, the correlations between a La Nina and the map shown below leave plenty of wiggle room, especially early in the winter.  Later in the winter is when the great southern US storm deflecting property of a La Nina has its greatest power, so it’s really good that we’re getting slammed early by decent rains; it might be a very dry late winter and spring.

Remember 1971-72?  And how wet it was in November and December in the SW, and then poof, almost nothing in the way of precip after January 1st?  It was awful. (I was weather forecasting in Durango, CO, then.  ((Hay! Not for TEEVEE, but for a randomized cloud seeding experiment!))


Had some pretty Cumulus clouds yesterday before the gray Nimbostratus layer moved in.  Here are a couple of shots around the Catalina area.  Always nice to see snow on the Catalina Mountains.

The last one is from today showing the gorgeous scenes, changing by the minute as the cloud shadows roll by, of the low level on the snow on the Catalinas.   Even here at just under 3200 feet elevation, last night’s rain ended with light snow for a few minutes.

Mods (from U of AZ Wildcats) don’t see precip from this next cold trough, one that lands on us tomorrow.  Darn.

Suddenly, it occurred to me that I want you to look at these forecast maps from IPS Meteostar for the next 15 days.  Just changed this to the intermediate model run, updated at 06 Z, 11 PM LST.  Much more “interesting”–means this writer saw MUCH more precip in AZ on the updated model run just now.  Check out the massive trough 12-15 days out and cross fingers.  Man, this is an exciting new change!

The End.

Ken might be bringing leftovers on Thanksgiving Day

Kenneth, that spinny thing with the eye hole, shown in this 24 h loop feasting on the warm waters about 500 miles south of Cabo,  seems inclined to drop in late on Thanksgiving Day with his leftovers.  How rude and wonderful at the same time!   Most of you (2 of 3 the three people who read this blog) will find this 24 h loop quite interesting and you might spend your whole day here questioning, “What does it all mean?”,  like the philosophers do.   So, be careful and don’t let your whole day slip away here.  I’m tempting you…

Check out these two snapshots for TG evening and Friday morning from this model run from the Canadians and the streamer of rain and moisture that comes in to SE Arizona on Thursday (lower two panels):

Of course, many of you may feel the Canadian model runs should be banned from this site based on some recent over-predictions of rain here.  And so you may wonder why I have gone back to a model that has let us “Catalonians” down so much recently.

Why, in fact,  DO I show this Canadian model output?

Because it has the most rain for SE AZ in it compared to other model runs, just like the last time it let us down!  I couldn’t help it.

Look at all that red coloring in the 2nd image, lower left panel for Friday morning (indicating the amount that fell in the prior 12 h while we were over eating and then trying to sleep on an overly full tummy but we might have a pounding rain to provide a “white noise” to help us get through that tough night)! (Stream of consciousness writing there).

Only yesterday, that same model showed the leftovers from Ken bypassing us for New Mexico.  Sure they need the rain, too, but this run from last night made me happier.  So, I am quite happy this morning with this model change showing more rain here in spite of set backs in other areas of life which I caused myself, dammitall, by not waiting to get more facts and instead relying on gossip in forming a key assessment that ultimately resulted in an inappropriate action that ruined a friendship.  (More stream of consciousness writing…) Oh, well, back to weather…

We have to remember that this model run is the LATEST run, and therefore is based on “mo better data” because its closer to the predicted event than those model runs that did NOT show so much rain here.   So, as a “scientist” I can show this latest run that shows what I want to happen and hold my head up as a truly objective observer since it was based on newer stuff;  it wasn’t just ME wanting rain.  On, the other hand, I hid from you those earlier model runs before this one that did not have much rain here with this “incoming” (trough).

So, in sum, you ARE getting a selective presentation of OBJECTIVELY produced data.  I wonder if anybody else does this?

Also, yesterday was truly stunning in clouds, with some honest-to-goodness Cumulonimbus clouds sprouting up yesterday morning.  They were so pretty.  And you got to see great examples of cloud tops “glaciating” (turning to ice) right before your eyes.  Didn’t hear any thunder, but there could have been some.  And then we had the late afternoon sun and those dramatic cloud shadows (produced by those much shallower Cumulus clouds) on the Catalinas.  Here are some examples for your visual pleasure.  BTW, we didn’t get hit by the cell cores.  So, rainfall here was only 0.02 inches; 0.03 inches, at Sutherland Heights (last photo).

The End except for this part.  Many of you have asked, “What was that recent quote by Mr. Cloud-Maven person in the Wall Street Journal about, anyway?”  Maybe they had the wrong Cloud-Maven person…

Well actually no one has asked that question…    But its an interesting story (I think) for those who write about science probably than for those who do science (he sez).  Maybe, in a display of particular grandiosity–after all, only the great scientists of our day are asked his/her opinion about a matter of scientific import in the WSJ!–explain what that was all about one of these days. Smiling very megalomaniacally here.   Hahahahah, sort of.



Likable model runs continue; one of the best overnight!

Tired of being dry?  Tired of having dry washes?  Tired of seeing dust raised on your gravel road?  Maybe too much dust on your late model car?  Maybe you’ve been thinking about wanting some more humidity and cloud cover with RAIN to make to make you lose that feeling of fatigue and boredom?  Well, then this model run’s  for you!

Yes, that’s right, Hilary will cure your blues and blue skies!   Yes, that’s right no more fatigue, lack of interest in life, and overall dullness due to too much sun and blue sky with last night’s model run!   See below, from IPS Meteostar:

Only 108 h (morning of October 1st),  top panel.  Hilary (small purple blob and low pressure) is cruising into central Baja, and some rain has already spread into AZ.

Second panel, valid in 144 h, valid for Sunday afternoon, October 2nd, a tiny purple blob can be seen over my house here in Catalina, SE Arizona. How great is this?  Lets hope nothing changes in these model runs for the next 144 hours!  (Technical Note:  that’s not possible, but to HELL with that anyway! )   This model output looks great now, and it’s what I want to believe will happen.  Maybe I just won’t look at the later model runs; HELL they go back and forth anyway on Hilary and where she will go.)

Lastly, there are some cloud shots below with a bit of science, mostly from yesterday.

Now even yesterday, some rain “appetizers” were around by evening.  I am sure you noticed.  Now its gonna take a coupla days for this to “develop” and this wetting will be due to the remains of Hurricane to tropical storm, Hilary, there down Mexico way right now.  According to the word on the model street, Hilary crashed across mid-Baja while turning toward the northeast and then goes over my house as a rain blob in 144 h 12 minutes (hahah), or in normal speak about six days from now (see below).  Still dicey that far out, but its what to believe in.

In the meantime, some of yesterday’s surprisingly (to me, anyway) active Cumulus clouds, beginning with a baby cloud over Charoleau Gap, NE of Catalina.  Since it was before 11 AM, this was a sign in the sky that we were going to have an active day of Cumulus clouds, ending with a nice sunset with a mixture of Stratocumulus, Cumulus, and shallow Cumulonimbus clouds, the latter responsible for the light rain off to the south and west of Catalina shown in the second two photos.

Technical information:   The first cloud photo was taken on Sunday, not yesterday, Monday as it is written above, but there COULD HAVE BEEN a cloud like that yesterday and so I used it anyway (haha, sort of).

Second with areas of rain dropping out of these higher based clouds (14,000 feet or so above sea level, 10-11 Kft above ground level) and with base temperatures of about -5 C (23 F), it was actually SNOW falling out of these clouds right at base, melting into rain below that.

Quiz:  How cold were cloud tops to produce virga/snow/rain this thick as you see in the second two photos?  Probably lower than -20 C (-4 F).  At say, -15 C (5 F) there almost certainly would not have been this much “stuff” coming out.  This assertion from your writer and self-proclaimd “expert” in ice formation in Cumulus clouds (“hey”, I got journal pubs!)

The Tucson storm passes by Catalina like so many other September storms

With continuous thunder and threatening skies for Catalina, the mammoth Tucson storm that dropped a record 2.83 inches for the wettest day ever in September at the International Airport passed by Catalina early yesterday afternoon.  Here’s what a fraction of it looked like (using a bad ISO setting, darn it).  Also at the TUS AP it has become the wettest September of record halfway through the month with over FIVE and a half inches!

Of course, we here in Catalina land have been missed by most of those heavy September rains and have had only a crummy 1.17 inches.  Still, better than nothin’.   And there have been some fabulous sights during these past days.  Below are a couple of shots from yesterday.  That easily visible roiling motion in that last shot, if you saw that Cumulus congestus-going-to-Cumulonimbus, was a real indicator of how unstable the air was, that is, how easily it could go upward yesterday.  This situation us due to the cooler air aloft we have right now, along with mid-80 temperatures at the ground.   This is the kind of roiling, churning action you see in those big boys in the Plains States, East, and South when severe weather lurks.

Mods think we have a chance for rain today, too.  Maybe it will be our time, we will win the rain lottery today.

Below, thanks to the U of AZ, we have a time lapse movie of part of the storm, anyway, to the right side of the image.

Dreamy weather ahead:

Of particular excitement in the longer range NCEP (“government”) models, although almost certainly wrong as they usually are that far in advance, is that a tropical storm advances toward Arizony in early October.  Mark your calendars.  Might as well.