Category Archives: Cloud seeding

One of the greatest Seattle days in the history of Catalina, Arizona

Yesterday, that is.  It felt like I never left.  Only 49 F here; was 55 F in Seattle yesterday.

But the main thing that made it seem “so Seattle” was the persistent low Stratocumulus overcast, almost no sun whatsoever, and a little rain.  We picked up another 0.03 inches in a couple of morning episodes of R– (an old weather texting1 shorthand for “very light rain”) to bring the storm total here to 0.55 inches.  Of course, the best part of that overcast was that it allowed the ground to be damp for another day, helping the spring grasses and wildflowers by keeping the soil moisture in the soil and not flying away under a hot sun.  The worst part of the overcast that lasted almost all day, was that Mr. Cloud Maven person had the day completely wrong–thought it would break open in the afternoon to “partly cloudy” and so he was as gloomy as the sky.  You see, as a weather forecaster, you can’t even really enjoy a nice day if you didn’t predict it.  Had some sad 75 F days in Seattle when I only predicted 69 F;  everybody having summer fun but me.

Enough nostalgia, here are the clouds, even if you have no interest in seeing such boring clouds again:

6:56 AM.  Interesting little punctuated lenticular.  Mr. CMP has finsihed his blog and thinks the sky will break open in the afternoon.  Hah!
6:56 AM. Interesting little punctuated lenticular.  Mr. “CMP” has just finished  his long blog and thinks the sky will break open in the afternoon. Hah!


8:00 AM.  Stratocumulus tops Samaniego Ridge--with the turrets, you might lean toward adding the descriptor, "castellanus."  Note blue sky here, if you didn't see any at all yesterday.
8:00 AM. Stratocumulus tops Samaniego Ridge–with the turrets, you might lean toward adding the descriptor, “castellanus.” Note blue sky here, if you didn’t see any at all yesterday.  No precip evident.
8:02 AM.  Looking north toward S-Brooke.  Fine shafts of precip emit from Stratocumulus clouds indicating those regions in the cloud where there was more liquid water at one time, where these clouds are humped up like those Sc clouds on Samaniego Ridge.  But, was the precip due to ice or the colliding drops process?  I wasn't sure at this point.  You see, after a storm, the clouds can be real clean, almost oceanic-like meaning they have LOW droplet concentrations, and when the droplet concentrations are low, the drops are usually larger and can get to sizes where they stick together when they collide (think 30-40 micron diameters).  You probably have a clue about that size, but it sounds great if you see this and tell a neighbor that, "those clouds might have drops larger than 30-40 micron near cloud tops."  Instant expert!
8:02 AM. Looking north toward S-Brooke. Fine shafts of precip emit from Stratocumulus clouds indicating those regions in the cloud where there was more liquid water at one time, that is, where these clouds are humped up like those Sc clouds on Samaniego Ridge in the prior photo (the precip from those clouds may have been out of sight).                                               But, was the precip shown here due to ice or the colliding drops process? I wasn’t sure at this point. You see, after a storm, the clouds can be real clean, almost oceanic-like meaning they have LOW droplet concentrations, and when the droplet concentrations are low, the drops are usually larger and can get to sizes where they can stick together when they collide (think 30-40 micron droplet diameters). You probably don’t have a clue about those sizes, but it sounds great if you see rain like this and tell a neighbor that, “those clouds might have drops larger than 30-40 microns in diameter near cloud tops.”  Instant neighborhood expert!


8:06 AM.  Then the clouds to the west of Oro Valley and Catalina began to produce fine precipitation, definitely looking like a true drizzle event (caused by colliding drop rain formation process), at least to me at this point.  This is a rare event when very light rain or true misty drizzle (tiny drops, close together) occurs in Arizona.  Usually our clouds have too many droplets from natural and anthropogenic sources and the cloud droplets stay too small to collide and stick together, instead bumping around like marbles with all the surface tension they got.
8:06 AM. Then the clouds to the west of Oro Valley and Catalina began to produce fine precipitation and advance on Catalina.  How nice.   Definitely was looking like a true drizzle event (caused by colliding drop rain formation process), at least to me at this point. That process is a rare event in AZ when very light rain or true misty drizzle (tiny drops, close together) forms like that. Usually our clouds have too many droplets from natural and anthropogenic sources and the cloud droplets stay too small to collide and stick together, instead bumping around like marbles with all the surface tension they got.  And then because they’re all tiny, they don’t have much impact when they hit, there’s not a lot of velocity difference like there would be in a cloud with a broad droplet spectrum, the kind of spectrum we see in “clean” clouds where drops bigger than 30 microns are a plenty.   Note trails of precip coming down in center.  BTW, to go way off topic, to distract from how bad my forecast was, in “hygroscopic” seeding, particles like salt are introduced at cloud base to encourage the formation of rain through this process in polluted Cumulus clouds.  Worked in Saudi, based out of Riyadh, winter of 2006-07, flying in a Lear jet, helping to select Cu for random seeding using that methodology2.  Our office at the government met building, I recall, was cleaned  by the “Bin Laden” group.   Hmmmm.  Maybe its a common name there, to go even farther off topic.
10:09 AM.  So Seattle! (Have to make up for that last bloated caption.)
10:09 AM. So Seattle! (Have to make up for that last bloated caption.)
4:49 PM.  And that's your entire day.
4:49 PM. And that’s your entire day.
6:27 PM.  Sunset tried to do something.  But, like the day, it was like that sugar icing on a stale cinnamon roll, just didn't quite make it, though cinnamon rolls are quite good as a rule.
6:27 PM. Sunset tried to do something. But, like the day, it was like that sugar icing on a stale dried out cinnamon roll, just didn’t quite make it, though cinnamon rolls are quite good as a rule.

Today’s clouds

Some residual small Cumulus, maybe clumping into a larger group this morning for a bit, which you would then refer to as Stratocumulus. Should gradually diminish in size and coverage until almost completely clear in the afternoon.  Expect a north wind in the afternoon, too.

The weather ahead

There isn’t any, well, not right away, but WAY ahead….

Chances for rain begin to pick up after the 19th as we enter the “zone of curl”, “cyclonic curls” in the upper atmosphere with a lot of “vorticity” in them again, with temperatures falling back to normal values.   Pretty tough to have warm weather for long at this time of year in AZ.   You see, its troughs like to “nest in the West” in March, April, and May, even when they’re not strong and far enough south to bring rain, maybe only wind. Its a climo thing, and it causes many areas of the West to see an increase in precipitation in March from February, and also halts the rapid rise in spring temperatures (especially in Seattle, hahahaha, sort of).

This because the global circulation pattern, responding to the climb of the sun in the sky and warming continents in the northern hemisphere, those forces acting on the position of the jet stream, and weakening it here in the NH (northern hemisphere), is changing the jet stream pattern so that storms begin to move southeastward from the north Pacific across the Pac NW into the Great Basin area in the spring, bringing cold north Pacific air into the West. There was a great report about this phenomenon by old man Bjerknes out of UCLA with his Ph. D. grad student, Chuck Pyke, back in the mid-1960s.  Pyke was a UCLA sports nut, BTW, to add some color to this account.

We won’t see that “trough in the  West” pattern for awhile here in our “oasis of warmth” now about to begin, but count on it returning, as it appears to do late in the model runs from last night.  Climo is forcing it.

The End, except for footnotes.

1Yeah, that’s right. Weathermen, as we would say it then,  were way ahead of their time,  “texting” each other long before kids thought of “texting.”   You might write a weather friend, if you could find one:  “We had a TSTM to the S with FQTLTGCCCG ALQDS last night for a few H. MVD N.”    PIREPS, SIGMETS, too, were all “texted” and texted by teletype! Tell your kids.

2Was under the aegis of Research Applications Program (RAP) at the National Center for Atmospheric Research (NCAR) in Boulder, CO.  Money was good…though not nearly as much as you would make as a TEEVEE weather presenter (hahaha).  I was a post retiree guest scientist for RAP NCAR.  Clouds could be real bumpy there in Saudi, thought I was gonna die once as bottom dropped out of the Lear going into Cumulonimbus at night that one time.  Pilot liked to cut it close between the hail shafts and the rising parts of the Cu with little or no precip, using his aircraft radar.  But sometimes, it was a little too close…and we got into the shear zone between a strong updraft and the downdraft.

Seeing red

Well, here it is, the NOAA Catalina spaghetti output for March 8th, 5 PM AST, hold the sauce:

The 564 decameter contours over Catalina and environs on March 8th at 5 PM.
The 564 decameter height contours for 500 millibars over Catalina and environs (in the center) on March 8th at 5 PM. The yellow line is the 5 PM AST model prediction, and the gray pixel in the lower left corner is what’s left of the same contour (after I cut and pasted) yesterday’s 5 AM AST prediction. They were pretty much showing the same thing.

The plot at left, with likely a Guinness record for a long, thin caption, pretty much guarantees a big trough of cold air here by then, another door opens into winter, which seems to be gone right this moment, and, being March, you might be thinking, “la-dee-dah, no more winter here in southeast Arizona.”  But as I often point out to my reader, and while trying to be a bit delicate about it, “You’d be so WRONG! I can’t even describe how WRONG you would be!”  So keep that balloon-like parka ready, heck, there could even be some snowflakes with this.

And, of course, I am a be little disappointed, well, royally, because you should have seen this coming in the red dot-plot at left for Catalina on March 8th already, and I wouldn’t have to admonish you again.  Oh, well.

BTW, the “red dot” is a baseball term used to describe the appearance of a slider coming at the batter–there’s a red dot in the center of the ball caused by the spin and where most of the red lacings appear to be concentrated because the pitcher had to grip the ball a certain way.  Seen’em, at one time.  Of course, you wouldn’t remember the great pitchers like Lee Goldammer  of Canova, SD, or Dave Gassman; the latter amassing over 4,000 strikeouts in South Dakota summer baseball league play. It was a big story in the Mitchell Republic–they keep track of that stuff there (amazing and charming).  Lee Goldammer pitched a DOUBLE header and his team won the SD State Tournament  back in the late 1960s.   (All true!)  You see, Lee Goldammer struck me out on three pitches in 19721.  Man he was good!  I had hardly gotten to the plate, and I was walking back again!

Had a nice sunset a couple of days ago, some pretty Cirrus clouds again.  Where I’m from (Seattle), Cirrus and sunsets are generally obscured by Stratus, Stratocumulus, and every other kind of cloud imaginable so that you don’t see them often because those clouds extend for thousands of miles to the west where the sun is setting.

6:28 PM, February 27th, not last night.
6:28 PM, February 27th, not last night.


1I was working that summer for North American Weather Consultants as a “radar meteorologist” in Mitchell, SD, directing up to four cloud seeding aircraft around thunderstorms.  But when it wasn’t raining, I could play baseball for the Mitchell Commercial Bank team.  The project was under the aegis of the South Dakota School of Mines,  was statewide in 1972.  Unfortunately, for the people on the ground, one of the aircraft was seeding a storm in June of that year hat dropped 14 inches of rain in the Black Hills, and the ensuing flash flood took over 200 lives.   “Hey”, it wasn’t one of my aircraft.  Ours were in the other end of the State.

Cloud seeding was absolved in the disaster, which was correct;  the weather set up that day did it.   No puny aircraft releasing stuff could have had any effect whatsoever.  However, had that 14 inches filled a dry reservoir to the top and saved a city from a water famine, what would the seeding company have claimed in that case?

I know.   It happened when I worked a project in India, the water famine there making the cover of Time magazine in 1975.  The reservoirs in Madras (now, “Chennai”), India, where I was assigned by Atmospherics, Inc., as a “radar meteorologist” whose job again was to direct a seeding aircraft around storms, were at the bottom, just about nothing left, when I arrived on July 14th, 1975.

But on the third day I was there, July 16th, 1975, a colossal group of thunderstorms developed over the catchment area of the Madras reservoirs and, naturally,  our one twin-engined Cessna was up seeding it.  It was my job to see that we had a plane up around the thunderstorms.

Five to 10 inches fell in that complex of thunderstorms with tops over 50,000 feet, and there was a flow into the Madras reservoir (oh, really?) for the first time in the month of July in about 14 years.  July is normally a pretty dry month in the eastern part of India, with Madras averaging just over 4 inches, only a little more than we do here in Catalina in July.  The main rainy season in Madras is October and November, during the “northeast” monsoon.  This is what those giants looked like:

Looking west-northwest from the Madras Internation AP at Meenambakkam, India
Looking west-northwest from the Madras International AP at Meenambakkam, India, 1975.

But as a meteorologist, I saw that a low center had formed aloft over southern India, weakening the normally dry westerly flow of the “southwest monsoon” across southern India after it goes over the western Ghats.  This weakening  allowed the moist air of the Bay of Bengal to rush westward and collide with that drier westerly flow and set up a “convergence zone” where the two winds clashed and the air was forced upward forming huge, quasi-stationary Cumulonimbus clouds.

Below, what I look like when I am in India and starting to be skeptical about this whole thing, “Is this going to be another cloud seeding chapter like the one in the Colorado Rockies, to graze the subject of baseball again?”

First row, 2nd from left.  Our pilot sits next to me.
First row, 2nd from left. Our pilot sits next to me.

As before in Rapid City, the weather set up the deluge; no aircraft releases could have made the least difference in such powerful thunderstorms.  While the leader of the seeding project did not take credit for the odd flow into the reservoir that July, it was pointed out to the media, without further comment that, “yes, we were up seeding it.”

The odd storm with that comment, sans a description of the weather set up that did it, made it too obvious to the uninformed that seeding had done it.  The Indian met service was, of course, outraged, and did their best to “fill in the blanks”, but the sponsor of the project, the Tamil Nadu state government, was unconvinced because it was obvious to them what had happened, and, after all, it was what they paid for!

I had already been disillusioned while working as a forecaster for a big, randomized  cloud seeding project in Durango, Colorado by 1975, and this project was to add more “fuel to the reanalysis fire” that I was later to be known for.  (hahaha, “known for”;  I was despised in some quarters for checking their work after they had published it and it was being cited by big scientists, and I mean huge,  like the ones in the National Academies, but like you when you thought summer was here NOW and there would be no more cold weather, THEY were so WRONG!  I can’t even describe how WRONG those national academy scientists were,  like the ones in Malone et al 1974 in their “Climate and Weather Modification;  Progress and Problems” tome.) ((I knew they were wrong because they talked about clouds and weather associated with cloud seeding experiments in the Rockies, and I was seeing how at odds those clouds and weather was with the way it had been portrayed in the journal literature by the scientists who conducted the precursor experiments to the one I was working on in Durango.))  (((Wow, this is quite a footnote, if it is still one.)))  ((((Still worked up about that 1974 National Academy of Sciences report, but don’t get me going on the 2003 updated one, which they botched royally, including not even citing the work I did correctly!  How bad is that??????))))  As the title of today states, “seeing red.”

The reason for going to India in the first place was that it had been indicated in our peer-reviewed journals that randomized seeding in Florida, that clouds like ones in India,  had responded to cloud seeding.  Besides, I had an ovwerwhelming desire to see giant, tropical Cumulus and Cumulonimbus clouds up close!  BTW, the Florida results fizzled out in a second randomized phase.

End of footnote I think….

Stratiform clouds bring steady rain and snow; sixteen hundredths to Catalina

“Sixteen hundredths”, originally a song by a boy group of that day so long ago, The Crests, about a light rain that fell in May in southern California, an event that is quite rare and exciting at that time of the year there.   But then practical and marketing considerations caused the song to be revised to one about candles of all things.  How odd.  I thought you might like to know some reliable history behind that venerable song, one that made us cry, it was so sweet, and think about, as boys, how much we liked girls when WE were sixteen or so.

Yesterday, while Mr. CMP (“cloud maven person”, but using acronym in trying to be as indirect as possible here) was making some fun of students mixing up units in their calculations of pressure at  various heights in the atmosphere, he himself was mixing up cloud “units”, by informing his reader that cumuliform clouds, some dropping graupel, would be seen over Catalina yesterday, not stratiform, sky-covering Altocumulus, followed by great masses of Stratocumulus underneath it, combining later with gray, dank, Altostratus, a scene that finally evolved in the mid-day hours into Nimbostratus with light rain, sometimes with light snow mixed in!  Briefly, too, it was ALL “surprise” snow!

The total, 0.16 inches, was also about sixteen times more than CMP thought would fall from that perceived marginal weather producer. (Note:  the U of AZ local model’s 11 PM run the night before had it predicted perfectly!  However, in some kind of bloated self-evaluation of skill levels, CMP did not consult that model until it was “too late.”)  Today, I am quite confident, however,  that I really don’t need to look at that model…

What is going on here? Fallibility, I calls it, human fallibility.  Remember that old saying about pencils with erasers at the end?  So simple and yet, profound.

Oh, well.  All’s well that ends well, and the “well” ending was one of a nice little rain mixed with snow (will burn your CMJ tee if you refer to rain mixed with snow as “sleet”!) and beautiful snow down on the Catalinas, so pretty yesterday evening as the clouds lifted.

Today a fine day with small Cumulus clouds, very photogenic again as this kind of wintertime day is here.   The mountains should be spectacular, too, due to the cold air that remains that will allow them to be white down low for a few hours this morning.

Pima County precip totals here.

Precip totals from the U of AZ network here and the national CoCoRahs org here for AZ totals.  The measrements at rainlog will indicate that they are for yesterday, the 11th, while the CoCoRahs convention, to assign the rain to the date it was reported,  will show the totals for our storm using today’s date, the 12th.  You’ll have to wait until about 8-10 AM to get most of the loggers’ reports.

The most I saw in the Pima County gage network was 0.43 inches, an amazing amount, down in Avra Valley.  Shocking, really.

BTW, the cloud regime that CMP foresaw for Catalinaland was just to the west of us, around Ajo, AZ, not that far away astronomically speaking.  And at sunset yesterday, you could see those Cumulonimbus clouds on the horizon coming into view.

5:53 PM.  The forecasted Cumulonimbus clouds begin to come into view.
5:53 PM. The forecasted Cumulonimbus clouds for Catalina begin to come into view.  I wish I could make this image bigger, maybe in 3-D so you could “feel” this cloud coming at you.

To cry-baby about it a bit more about a missed cloud forecast, this “visible” wavelength satellite image:

1:45 PM AST.
1:45 PM AST.

Some un-Cumulus scenes from yesterday:

10:30 AM.  Altocumulus perlucidus undulatus and Stratocumulus begin overspreading the sky.
10:30 AM. Altocumulus perlucidus undulatus and Stratocumulus begin overspreading the sky.
11:41 AM.  Dark bases of Stratocumulus-Cumulus line up with the wind and head toward Catalina.  Virga spews in the distance on the right.
11:41 AM. Dark bases of Stratocumulus-Cumulus line up with the wind and head toward Catalina. Virga spews in the distance on the right. Above these clouds was an icy layer of Altostratus.
11:58 PM.  Mounding tops of Stratocumulus-embedded Cumulus become infected with ice and spew forth virga.  Now under this guy, there may well have been a couple of graupel.
11:58 PM. Mounding tops of Stratocumulus or embedded Cumulus become infected with ice and spew forth virga. Now under this guy, there may well have been a couple of graupel. Above these clouds was an icy layer of Altostratus that helped impregnate the lower Stratocu and Cu with ice, kind of like seeding them.
1:17 PM.  The lumpy and dark looking bases had disappeared in the virga and snow falling from the thickening Altostratus layer as it became, Nimbostratus.  What you're looking at here is a classic example of snow melting into rain that appears to be the base of the cloud, but its really a transition zone that reveals the snow level.
1:17 PM. The lumpy and dark looking bases had disappeared in the virga and snow falling from the thickening Altostratus layer as it became, Nimbostratus. What you’re looking at here is a classic example of snow melting into rain that appears to be the base of the cloud, but its really a transition zone that reveals the snow level.
3:14 PM.  Snowing hard in Catalina for a few minutes.  Here's what it looks like, coming down at you.  Some aggregates of snowflakes were more than an inch across.
3:14 PM. Snowing hard in Catalina for a few minutes. Here’s what it looks like, coming down at you. Some aggregates of snowflakes were more than an inch across.
5:42 PM.   The result of our little storm on the Catalina Mountains, Samaniego Ridge.
5:42 PM. The result of our little storm on the Catalina Mountains, Samaniego Ridge.

The weather ahead into March

Gotta ride the storms, ones already predicted as of yesterday here over the latter half of this month. Never good to “yo-yo” on a forecast, as forecasters will tell you.

However, not getting help again in this longer range musing from the NOAA ensembles of spaghetti; site is still down, so riding bareback here so-to-speak, using a western idiom (or is it “idiot”?) In sum, Arizona to end up with above normal precip when whole state considered. This due to being in the bowl, the trough bowl, though breaks in storms, and nice weather, sometimes for several days at a time, will try to fool you into thinking you’re not.

Going farther out on a limb, twig, really, looks like the active storminess will continue well into March. We seem now to have a wet pattern going, though in a desert, its not THAT wet compared to Washington State or elsewhere. Stand by for occasional updates. Am excited for wildflowers now; there may be some!

The End.

Climate kerfluffle reprised in southern hemisphere

With no rain in sight, and only modest temperature fluctuations ahead, some reading material is presented to you today with commentary today, a “soapbox day.”

Cloud photos from yesterday are at the bottom if you want to skip to that and avoid thinking about things because its too early in the morning to get riled up.

I will start with an opinion piece concerning climate change and climate science from Australia.   It also mentions a recent event in the climo community concerning a Southern Hemisphere temperature reconstruction and the apparent rejection of what would have been an important paper by the peer-reviewed journal it was submitted to after crucial errors were found by an outsider/reviewer.  The author of this opinion article also mentions “climategate” a chapter of science that had a profound effect on this writer.  Now there are polemical aspects, not all of which this writer would agree with, still, its worth reading:

Speak Loudy and Carry a Busted Hockey Stick

The link to this article was circulated to our Atmos Sci Dept by one of my best friends, and really a science hero to me, Mark Albright, the former Washington State climatologist.  Mark was a mild-mannered researcher lurking in the background at the U of WA for many years until he got upset over what he (later joined by two allies there) was to show were vastly exaggerated journal-published and media accounts of snowpack losses due to GW in his own backyard, in the Cascade Mountains of Washington and Oregon.  Mark felt science had been corrupted by dogma, perhaps the pursuit of funding; he has not been the same since.  Believe me, I know what he has been through.

A retired distinguished professor at the U of WA Atmospheric Sciences Department circulated a counter articleto the one that Mark circulated, also worth reading for the “other side.”  It appears below, along with that professor’s note about the article Mark circulated.  I felt this note by the professor should be included, too:

“Worth reading is this article by a Reagan/Bush Science board appointee. It demonstrates objective science versus the Australian article which is full of vituperation, accusations without substance, slander, and very little science.”

In the headline of this second article,  the word “denier” is used in its title as a pejorative, mass label for those who question some of the global warming publicity stunts (assigning particular storms like Sandy to GW) down to results published in peer-reviewed journals, such as reports of exaggerated snowpack losses.  Not good, and that headline tells you where that article is headed: criticism is not to be tolerated.  But it also shows that the majority of science being published on climate change supports the finding that a warmer earth is ahead.  But there is a reason for that; its being pushed by the monumental amounts of money being poured into that climate research domain.

There are many of us out there that do believe that funding is pushing the research on global warming in one direction in this job-poor era we’re now in, just as it did, and still does, in the cloud seeding domain:  no one ever got a job saying cloud seeding doesn’t work.  In my own career–yes, Mr. Cloud Maven person had a professional research one, and one spiced with controversy1 over several decades–the opinion article from Australia rings true in many aspects about how science works and what influences a preponderance of “conclusions” that get published in journals.

In the climate funding domain, don’t look for more funds if you conclude a million dollar study by indicating that you didn’t find any sign of warming over the past 30 years, as is the actual case in the Pacific Northwest.  NO ONE is going to touch that hot potato and serve a finding like that up to a climate journal.  Its not gonna fly.  It makes explaining global warming difficult.  And as Homer Simpson advises, “If something’s hard to do, its not worth doing.”

But at the same time, a counter finding to global warming presents to those of us who try to be truly ideal, disinterested scientists, a fabulous opportunity to look into something that is not immediately explicable.  As scientists, we should live for opportunities like this!

But will it happen, will some brave soul at the University of Washington or elsewhere delve into this counter trend and try to explain why its happened in a journal article? Its hoped so.

But those of us, still on the GW bandwagon, if grudgingly so due to the actions of some of our peers, know that regional effects of GW are dicey.  Some areas will warm up more than others; cooling is possible if the jet stream ridges and troughs like to hang out in different positions than they do today.  And of course, if we smog up the planet too much, all bets on warming up much are off since clouds act to cool the planet, and pollution makes clouds last longer, especially over the oceans where pollution can interfere with drizzle production, which helps dissolve shallow clouds, and pollution causes more sunlight to be reflected back into space.  The cloud effects are being more carefully, precisely evaluated in our better computer models.


It is ironic, too, that the second article, the one passed along by the professor, ends with the mention of plate tectonics “as the ruling paradigm of science” as it is.
But, some word about how that paradigm came about; it was a “long and winding road.”

Alfred Wegener, a meteorologist,  first proposed the theory of continental drift/plate tectonics around the turn of the century.  A nice account of this science chapter about origin of the theory of plate tectonics is found in the book, Betrayers of the Truth, by then NYT science writers, Nicholas Wade and William J. Broad.

Because Alfred Wegener was a meteorologist, however, and NOT a geographer, namely was an outsider to the official science community studying the continents and how they got that way, his ideas were laughed at, not taken seriously for more than 40 years!  Only in the 1960s was the idea of plate tectonics accepted.

I mention this tectonic chapter of science because there is a similar chapter that reappears constantly now in the climate debates.  Several of the strongest critics of GW results, critics that have delved deeply behind the scenes into published findings of climate change in a scientific manner, much as this writer did concerning cloud seeding experiments in the 1970s-1990s, are criticized for being “outside of the group”, just  Alfred Wegner was in his day rather than those “in the group” considering and acting on whether the findings of outsiders are valid.

Fortunately, this is beginning to change because, guess what?  Outsiders have found some pretty important stuff that HAD to be addressed in spite of the desires of some idealogues out there pretending to be objective, disinterested scientists.   Science as a whole, still works.

A cloud note: Alfred Wegner is also known for proposing the idea that ice crystals in the presence of supercoooled water (a common event in the atmosphere) grow and fallout, leading to precipitation at the ground, known as the Wegner-Bergeron-Findeisen mechanism.  Every 101 meteorology textbook points this out.

The last photo below is a demonstration of that effect; those sunset supercooled Altocumulus shedding a few ice crystals that grew within them.


 Yesterday’s clouds

7:33 AM Cirrus fibratus radiatus. Sometimes perspective makes banding look like its converging or radiating. I estimated that this was not the case here.
4:31 PM Parhelia-Sundog-Mock Sun in an ice cloud with hexagonal plate llike crystals, ones that fall face down and cause the light to be refracted and separated. Here’s is a link explaining this phenomenon.
5:24 PM. A classic Arizona sunset due to the under lighting of Altocumulus perlucidus. Some very fine virga from these clouds can also be seen. When the virga is this fine, the concentrations, as you would imagine are very low and the crystals falling out are especially beautiful because they have not collided with
other crystals and broken into pieces as happens in heavy virga shafts.


1Some examples of the controversy the writer has been involved with:

“We don’t hate you but we don’t love you, either.”

This quote from a leading US cloud seeding scientist to the writer at an American Meteorological Society  conference on cloud seeding and statistics after his cloud seeding experiments had been reanalyzed by the writer.

“I want you to leave my office and don’t come back.  Just do your own thing.”

This quote from THE leading cloud seeding scientist of the day when I went to his country to see for myself the clouds he was describing in peer-reviewed journal articles, descriptions that I had doubts about. His descriptions were later shown to be far from reality.

And, from an outside observer, and well-known cloud researcher at the National Center for Atmos. Research in Boulder, a comment to the writer when he visited the University of Washington:

“I think the (cloud seeding) community sees you as a ‘gadfly’.”

From the Oxford Concise Dictionary, “gadfly”:

“A cattle-biting fly; an irritating, harassing person.”

Q. E. D.


El Nino may be in the works for next winter; stories from the field

Here you can read the latest statement from the Climate Prediction Center on the neutral conditions that have developed in the eastern Pacific Ocean–La Nina is gone–and what it sees for next winter from their computer models.  While things are not clear because they are so difficult to foretell, they are talkin’ El Nino some. As we know, the Southwest can benefit tremendously in rainfall when an El Nino develops, and so it is uplifting news to hear ANYTHING about an El Nino in the future and I though you would want to read that, too. Here you can see the last few weeks of global ocean temperature anomalies and how they are changing.

Why talk about next winter now?  We should always be looking ahead in life, planning retirement, vacations, what football games to attend next fall, the important things in life;  besides, there are no clouds to talk about, only hot air currents, maybe a dust devil, so I need some filler material.  Remember when newspapers used filler material to make columns come out even, add some little fact?  Those were great.

Too, I may have to dredge up some “stories from the field” to fill in the boring gaps in weather we have today, like that time they almost rolled over our VW microbus on that big boulevard in Madras (now Chennai), India, in August 1975.  That big boulevard was reserved that day for the funeral parade of freedom fighter, Kamaraj, (against the British) with Indira Ghandi leading it.  We should not have driven on it.  Hundreds of thousands of people lined that boulevard for miles that afternoon! You would not have believed that scene!

The crowd.   What I look like when I am in India (on the right)

I am still white-knuckled thinking about our knuckle-headed project leader who thought it was going to be OK to drive on that funeral route so we would get back to the hotel faster.  He ordered our driver to go onto that boulevard, and then told him to,  “just wave at the police”,  guarding the route as we drove down it.  We were returning from the Madras airport at Meenambakkam where we had been on standby to seed some clouds if they developed over a nearby reservoir catchment area.    We were the only vehicle on that boulevard as the people waited for the official parade.

But then some of the crowd, maybe just a dozen or so, took exception to our driving down that boulevard and rushed our microbus.   Our driver, sped up and slowed down in spurts, swerving left and right as well trying to shake people off his van.  And the ones trying to climb on it did fall off, thank god, but fortunately no one was injured (or run over!)

In another bit of luck, the windows of that microbus were completely opaque due to heavy condensation on the inner surface of the windows, and so the crowds could not see that it was three Anglos in the back of that damn bus violating that boulevard.  Heart pounding now as I relive that drive.

A bit farther, the driver somehow found a side street among the crowd and drove ever so gradually through all of those people lining the boulevard and finally onto the side street he knew was there.

That was an awful thing to have done and still regret being a party to it.  But, somehow, too, my life was spared so I could write this blog in Catalina, AZ.  Interesting.  It better be good!

The latest map below (May 9th conditions) shows that the “warms” have it overall in the global oceans, and what’s important for us is that the cooler-than-normal water in the eastern half of the Pacific along the Equator (representing La Nina conditions) has dissipated.

For comparison, shown this map for May 9th is one for February 1st conditions when our La Nina was holding forth.  Note the below normal temperatures along the Equator westward from South America across the Dateline on that map, and then look to the new one.

So there are no strong forcing factors at present to alter our climate from “normal.” Still means that the weather machine will continue doing its thing, hot, cold, rainy, extremes, etc., but there won’t be a dominant pattern, the kind that leads to a greater chance of drought in the Southwest and southern states as La Nina’s tend to do in late winter and spring. Yay!  Summers don’t seem to be much affected by either of these conditions.

 The Big One, that giant trough, is still on the way for implantation in the West, but only wind projected here

Dang.  No rain.  Likely we’ll hear about low temperature records in parts of California, Nevada, the Pac NW, extreme winds at various places, and hot and windy conditions here and in the Plains States.   Very little rain is projected out there as well, at least in the early going of this enormous trough and low system.  Starts affecting us on Wednesday; the TEEVEE weather presenters will be all over this one!

Let’s talk about May

Now in a really good web site about weather, clouds and climate, we would have talked about May around the first of May.  But let’s face it, this site really isn’t that great.  So now we’ll talk about the climate of May on May 11th.

Below is the rain frequency climate, such as it is, for May here in Catalina.   Surprisingly, to Mr. Cloud-maven person, there is no downward trend in the chances of measurable rain from the very first days of May until the end as was expected.  Instead, each day of the whole month has about the same small chance of rain from the 35 year record mostly made by the folks (Wayne and Jenny) at Our Garden here in Catalina.

Where the rising temperature graph for May, you ask? Well, I don’t do temperature. I am cloud and rain person. A nice graph of the temperature trend for May, which we know is upward on average for the whole month, can be found here at the Western Regional Climate Center, housed at the cloud seeding-inclined Desert Research Institute of the University of Nevada which issues misleading PR pieces on cloud seeding which they conduct for the State of Nevada (no, you won’t find them, in spite of being an academic institution, doing proper randomized cloud seeding experiments, but rather bogus-style “operational” seeding.  They’d be AFRAID of doing a proper long-term, double blind randomized experiment using independent evaluators!  If I was them, I would be afraid, too, about what such an experiment might tell their long term funders!  Don’t get me started on cloud seeding discussions!

Now, where was I?

Oh, yeah, climate.  Don’t get me started about the parallels between some aspects of the purveyors of global warming info (I’m talking exaggerations, not the prospect of it which I have to grudgingly go along with, “grudgingly” because I really hope there’ll be an ice age tomorrow when I read some of the exaggerations that come out for the purpose of scaring people,  like this or that storm or tornado was due to global warming.

Yes, there are parallels between cloud seeding claims and some of the GW ones, mostly, in this writer’s opinion, driven by the need for funding.

Now, an hour later,  back to that graph at DRI….  You can see that the temperature at the U of A rises steadily throughout May on average.   We knew that already, so there really wasn’t much point in showing it, but I feel a lot better now having exhausted some hot air myself.


The End.




Yesterday’s awful Cumulus clouds; better ones today!

From the University of WY Cowpokes, this awful sounding from yesterday afternoon at Tucson.  Where the two lines first pinch together, around the “500” label, is where the Cumulus cloud bases were yesterday afternoon (marked by the oval)!  To see why those Cumulus were awful ones with too much ice, check the temperature lines, the ones that slope upward to the right with the labels on the bottom, “0”, -10, -20, etc.   Yep, that’s right, the bottoms of those clouds were at 500 mb, and -20 C!  The Weather Cowboy sounding algorithm, the one that produces all the numbers in the column at right, thinks the bottoms of Cumulus clouds were even HIGHER, at 428 mb and nearly at -30 C (that “LCLP” number)!

So, the awful looking, dried out, Cumulus clouds have been explained.

Too high, too cold, too much ice.  Reminded me of the old days in Durango, Colorado, in the early 1970s.  Charming town, but awful place if you wanted to see Cumulus clouds without much ice.  Too high, too cold, and too much ice there, too.

What’s wrong with too much ice?

Too many ice crystals completing for itty bitty amounts of “condensate” (yes, Virginia, even at those temperatures, cloud begin as liquid droplets).  But when they are so cold to begin with, so many of the droplets freeze, that they all try to take the water from the ones that haven’t frozen (cause them to evaporate, the water molecules rushing to the nearest ice spec.

So when nearly ALL the droplets freeze, the ice crystals are all itty bitty as well, and can’t fall out, even though individually they may have a bit more mass in them than the droplets.  They just float up there and gradually die.

Stories from the field interlude

OK, gotta get this out…   In the domain of cloud seeding, where ice-forming nucleants are put into clouds, the phenomenon of having too many ice crystals would be called, “over-seeding”.  Believe it or not, deliberately “overseeding” clouds to make them look like the ones we had yesterday, and so that they wouldn’t rain has been tried!

Yikes.  Why?

The Coors Brewing Company, in the early 1970s,  did not want their hops in the San Luis Valley of southern Colorada (around Alamosa) spoiled by having rain fall on them at the wrong time.  The program was ended when alfalfa farmers in the same area, ones that WANTED RAIN, terminated the program prematurely with sticks of dynamite;  they blew up the seeding contractor’s radar, used to direct aircraft into the clouds to seed them.  Mr. Cloud-maven person, the writer,  was working in Durango in those days, on the other side of the mountains from Alamosa, on a scientific cloud seeding project (a randomized one) to see if seeding could cause more snow to fall from winter storms, so he was close to the “action.”

Yes, everyone gets excited about clouds and weather, especially alfalfa farmers!  Its so great.

Below a few shots of yesterday’s small, ice-ed out Cumulus.

The haze below this little Cumulus fractus cloud is due to ice having formed in it! Bad news from the get go if you're hoping for virga and rain later in the day.
Merely a Cumulus humilis, center, and having a bit of puffery. But its mostly ice. Quite awful-looking, really.

About today’s “better” clouds

Overnight there was an invasion of air from the east carrying increased lower level humidity. How cold will the bases be today after yesterday’s -20 C or so? Around 0 C our TUS morning sounding suggests. While that’s still cold, it should mean rain to the ground here and there in the fatter Cumulonimbus clouds that will be around even though they will be dominated by ice again. With these higher base temperatures, it means more water condensing in the clouds BEFORE ice forms. When that happens, you are likely today to get “graupel” forming in areas of the clouds where the condensation is greatest, and the ice just beginning to form. “Graupel” or soft hail, falls rapidly compared to ice crystals and aggregates of ice crystals (i.e., “snowflakes” to get away from jargon) and those graupel up there are likely to be what MAINLY gets to the ground today, melted of course, into raindrops. This because the “free air” freezing level is about 7,000 feet above us here in Catalina (3,000 feet elevation). Should be a fun day, reminding us of out upcoming summer rain season.

And, what do we think about when we think about graupel/soft hail forming in the clouds overhead?

Electricity, lightning!  Yes, these clouds will be getting “plugged in”, so to speak, this afternoon here and there.  Be watchful.


Nice display of Cirrus uncinus in the late morning as Cu began to form.

BTW, if you want a really expert discussion for today, go to Bob’s page here.  (He may weigh in on this later…) And,  of course,  our NWS here.  They seem to be getting pretty worked up and excited about today’s weather and all the wind that might blow out of our afternoon thunderstorms.

BTW, nice flowers out there in the desert now days; this on our “Arizona rose” (took about nine attempts to upload this!  Bad WP!)


The End.

“(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!


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.










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.”

So Seattle

Seattle nostalgia part

Got a little homesick yesterday with the weather the way it was here in Catalina.  Well, after 32 years in Seattle it seemed like home.  The dank, gray, low-hanging, lifeless, overcast skies of Stratus and Stratocumulus clouds hour after hour (spoken with emphasis on each descriptor using a whiney kind of emotional voice) reminded me of all the great times in Seattle, the friends, the occasional unsatisfactory girl friend (hahaha), the sports glory days in the Western International League semi-pro baseball league (well, there was one day in particular), the days as a Mariner batting practice pitcher in the equally dank Kingdome, an edifice that mimicked the skies outside, the 25 years or so of bike trips to and from the University of Washington under those same kinds of dank, gray, lifeless skies, and piddling rain we saw here yesterday.

And with people here driving around in the middle of the afternoon with their car lights on, it was the perfect replica of a Seattle winter day. Even the temperature cooperated here to mimic Seattle;  it only changed a couple of degrees from dawn to the mid-afternoon high of 47 F, some 20 degrees or so below normal.  Sometimes in Seattle, the temperature is the same all day because the sun is so weak and the layers of clouds, piled one upon the other, seemingly impenetrable to light and heat.

The Seattle mimicry was completed with some light rain in the morning here, raining just like it does in Seattle, barely accumulating hour after hour but there to annoy you.  We only had 0.02 inches after 7 AM LST, but it stayed wet all day here just like back at my old Seattle home.  The grass in the backyard there might be dry sometime in April, otherwise your shoes and your dogs come in wet everytime.

Yep, that’s what Seattle is like.   I loved it there….  Hmmmm.

Well, what I really loved was being at the University of Washington during the glory days of the Atmospheric Sciences Department when all the “big guns” in meteorology were there it seemed;  Holton, Hobbs, Wallace, Reed, Charlson, Fleagle, Bussinger, Leovy, Houze, and the job of flying around in clouds in the “CARG” aircraft, etc.  Their kind will not be seen, clustered together like that, anyway, again.  As a kid I tried to get autographs of the big stars in meteorology like Jacob Bjerknes at UCLA so that’s why being at the U of WA was so exciting.  They were to me like major league ball players were to other kids, though I did like Ted Williams and the Bosox in those halcyon days. Egad, enough!

A review of yesterday’s clouds below.  The first photo toward the Tortolita Mountains (obscured) and a near perfect example of Stratus, followed by two shots of Stratocumulus.

Weather and clouds part

Yesterday was interesting in several ways.  First the rain fell from clouds topping out at a modest -10 C, something we don’t see much of in Arizona.

Second, it was so dark during the day even as the clouds became shallower as the day wore on. Below are the two soundings from TUS for yesterday from the U of AZ, the first at 5 AM and the second 12 h later at 5 PM LST.  Where the green and white lines come together mark where the clouds were.  From that description you can see that they were topping out around 700 mb, or around 10,000 feet above sea level in the morning, and maybe 9,000 feet by evening at about -6 C.  No echoes were being observed by the afternoon.

But why?

Well, the cloud savant will know that there must have been a lack of ice crystals in those supercooled clouds in the afternoon (ones whose tops, at least, were below freezing.)  But why no ice?  Almost certainly it was because the cloud drops in those clouds were smallish, less than 25 microns in size, there were no “ice nuclei” active at those higher temperatures (a normal situation).  The lack of drizzle (fine misty rain that appears to float in the air) is evidence that the drops in those clouds did not reach sizes larger than 30 microns in diameter. Drizzle drops (those between about 100 and 500 microns in diameter, have often been associated with the onset of ice in clouds at temperatures of -4 to -10 C over the years.  But not always.

BTW, the formation of drizzle helps eradicate clouds by draining them of their liquid water, causing clearings.  So the absence of drizzle due to smaller drops helped “seal the deal” on a long day of overcast.  Also surprising to me was the amount of underlying haze yesterday, again evident in very strong crepuscular rays late in the afternoon.  See below, along with the rare example of liquid cloud mammatus formations.  That haze suggested to me that the drop concentrations in yesterday’s clouds were also pretty high, and helped keep the sizes of the droplets down by spreading the “condensate” on more particles. And guess what, those likely more numerous and smaller cloud drops helped make those clouds darker than clean clouds.   More sunlight is scattered back into space by dirty clouds than by clean clouds, so the bottoms of dirty clouds are darker even given the same thickness as clean clouds.  (This is a HUGE issue in global climate models, drizzling and not drizzling clouds because it effects the cloud cover, and the more cloud cover you have, the more CO2 warming is offset.)

So several factors likely went into making yesterday “so Seattle”; lack of precip later in the day, small cloud drop sizes, likely due to high droplet concentrations in those clouds, at least later in the day.  Lets hope it doesn’t happen again.   The End

Addendum on cloud seeding potential for yesterday

Yesterday was the perfect day for seeing what you can do by seeding clouds with dry ice–dry ice is more effective on days with marginally supercooled clouds.  Would there have been some rain on the ground?  You betcha with those low bases.  However, it is virtually certain that any rain would have been but a trace, or barely measurable.  The main thing that would have happened is that clearings would have ensued in the seeding zones, seeded by the way, by aircraft dropping dry ice into those tops.  So, a little precip, and some clearings, and those clearing would have likely triggered a widespread natural clearing if you could get enough holes produced by your aircraft.  The last photo shows would you can do when you glaciate a relatively thin layer cloud.   Were yesterday’s clouds thin enough for holes?  I think so.

More about holes-in-clouds while we’re waiting for the AZ rain in a few days

There have been a coupla comments on that aircraft effect in clouds blog of a coupla weeks ago and so I thought I would follow up with this sequence from the Atmos Sci Building rooftop at the University of Washington where I spent most of my time instead of at my desk.1

Here is a rarely photographed sequence of the effect of an aircraft on a supercooled cloud.  The first photo, right after a contrail-like feature was seen in these Altocumulus clouds.

Look at what seems to be a dark contrail-like line in the middel of the photo. The Altocumulus (perlucidus) cloud layer, mostly comprised of supercooled liquid drops, is probably around -20 C, though I did not get a PIREP on this day for some reason.

In the minutes after this first photo, the aircraft trail seems to disappear as it widens and the shadow lessens.  This stage is not shown because I didn’t realize what was going to happen until minutes later.   This second stage is almost impossible to pick up visually because there are no ice trails yet, nor is the cloud opening up at this time.  This “invisible” stage might last 5 minutes before you see the hair-like signs of a fallout of ice crystals.

This second photo is about ten minutes after the line in the first photo. Now it is clear that ice has formed, the crystals are growing and falling out as "virga", and a clearing is starting to open up.

Ice grows rapidly in the presence  of the supercooled drops.  Ice represents something of a low pressure center in the middle of all those droplets and that attracts the vapor from them, causing them to evaporate.  That vapor deposits as ice on the newly present ice “germs”/crystals created by the aircraft.   Since the drops are disappearing, before long, you get a hole or ice canal in the cloud where the droplet cloud used to be.

In this third photo, there is no longer any doubt about what's is going on. The hole is there, and its only a question of how much larger it will get.

The ice crystals shown above are clearly falling out (ever-so gradually because they are so small still, perhaps a few hundred microns in width).   Becasue they are so small, they usually evaporate well before any precip reaches the ground.  However, recently it has been shown that in deeper clouds and more moist conditions, that an aircraft can actually produce a bit of rain/snow at the ground due to this effect.

Here is last photo I took that day.

The ice crystal induced hole in the Altocumulus layer has gotten closer to exiting the liquid cloud (has moved to the edge of it) as well as expanding some.  This suggests that the ice cloud was moving faster than the droplet cloud, something that happens when waves in the atmosphere are producing the droplet cloud.   It was also getting closer to the observer, however.

Sometimes, if the cloud layer is lifting enough, the original Altocumulus clouds will gradually fill back in because all of the ice has settled below the liquid cloud layer.

For history buffs, holes in clouds with ice in the center, or ice canals were seen in the 1930 and 1940s, but as you can see, unless the observer saw the original trail (which they usually didn’t) no one knew what caused them.   Eventually an ice canal was was photographed in 1946 that was so convoluted it was realized that ONLY an aircraft could have done it.

Furthermore, that report in 1946 preceded the discovery of modern cloud seeding with dry ice by Vincent Schaefer in 1947 who performed his most convincing, and could be seen as ironic, demonstration of seeding with a similar convoluted ice canal as was seen in 1946 in a supercooled Altocumulus cloud layer  Its interesting in retrospect, as so many things are, that Schaefer did not have to drop dry ice on his clouds that day in 1947 in which he made history, but rather only had to fly his prop aircraft through them and likely would have gotten the same effect!

BTW, there is a lot of new interest in this topic, a new article recently appearing in Science mag.

I mention this cloud seeding benchmark since these aircraft events represent inadvertent cloud seeding, and in a sense they demonstrate that you CAN get something in the way of precip to fall out of a previously non-precipitating or barely precipitating cloud by seeding.  When clouds are already naturally precipitating, what happens when you do cloud seeding is subject to question; the science domain in this murky world is highly polarized.

The “Story of APIPs”–Aircraft-produced Ice Particles)  is told (in the usual “style” you will often find here) in the gigantic powerpoint “show” on this website under Sci Talks toward the middle of the show, around slide #472 (hahaha).

This ppt “show”, BTW,  is WAY overdone, but, what the HECK!  Why tell only “the whole 9 yards” when you can tell 12 or 14?


1Hahaha, sort of.   Sometimes, looking at those several thousand film shots from the rooftop of the Atmos Sci Building, I do wonder about that.  But then again, since I used 1/100 of a second exposures with my film cameras, these photos would only PROVE that I had been on the roof, maybe 30 seconds in 30 years there at the UW.

Feeling better now.