Category Archives: Cloud seeding

A review of a review of cloud seeding status

I put up a new page on this blog (see top header for “pages”)  for sciency types deeply interested in weather modification/cloud seeding,  my main avocation  “whilst” working in the met sector.    Its a many “commented out” review of NAS03 (shorthand for the National Academy of Sciences tome, published in 2003, “Critical Issues in Weather Modification Research.”  I also post it here for redundancy.  This is what I have been doing lately instead of reporting to you on clouds and dust.

The original document as long, and with insertions and commentaries, well, now what’s here is over 170 pages.  Only the weather mod technocrat among you will truly be interested.  I found a couple of errors, and have done a little re-writing just now (April 4th).

A Critical  Review of the National Academy of Science’s 2003 “Critical Issues in Weather Modification Research”

Why this review is so late is explained, in fact, I tell “all” the good and the bad and delve into, oh,  controversy.  Its not in the usual style of this blog, of course, since its a highly technical review.

Some background, if you care

My first job in the cloud seeding domain was with North American Weather Consultants, Goleta, CA, one of the oldest cloud seeding companies in America.  I was a student hire for the summer of 1968.  I was coming off my Junior year at San Jose State.   Robert D.  Elliott was president and founder of NAWC, which he founded soon after Vincent Schaefer’s stunning dry ice experiments showed that you could cause snow to fall out of supercooled droplet clouds when you converted them to ice crystals.  That precip-forming process is known as the Wegner-Bergeron-Findeisen process.

The remarkable event of that summer was that “Bob’s” friend, Tor Bergeron, (of the Wegner-Bergeron-Findeisen mechanism of rain formation) came one day to visit Bob and I got a photo taken with him!  In case you would like to see me with one of the “Fathers of Rain”, Tor Bergeron , or Tor himself, here it is ( I laugh when I look at this; can pants be any tighter?):

Tor and me, summer 1968, at the headquarters of North American Weather Consultants.
Tor Bergeron and me, summer 1968, at the headquarters of North American Weather Consultants.  He was also very interested in and supportive of cloud seeding.  OK, this shot was meant to provide some humor, something often attempted here.

I loved that job and the people there!  Cloud seeding was so interesting, too!  And I already about 20 years into my cloud-centric life, had chased thunderstorms in the southern Cal and Arizona deserts, and a hurricane in 1961, Carla, by then.  I knew what ice was in the sky.

Things kinda went downhill for me in the cloud seeding arena not too long after that when I joined, as my first job out of college, the Colorado River Basin Pilot Project, a massive randomized cloud seeding experiment that was going to replicate stunning cloud seeding successes published by scientists at Colorado State University.   Winter snowfall in the Rockies had been increased in certain situations by 50-100% in their own randomized experiments!  And the CRBPP was going to target those situations in the random decisions.

I started out as Assistant Project Forecaster in the fall of 1970, and then after some early personnel shuffling, was booted up to “Acting Project Forecaster”, forecasting the weather EVERY day, and calling all the random decisions that first season!  There was no “Assistant Forecaster” any longer.  I loved it!  Couldn’t wait to get to work!

If you don’t believe me that I forecast the weather for random draws in the massive Colorado River Basin Pilot Project cloud seeding experiment right out of college, then you’ll  have to see this “documovie” in which I make a forecast, filmed in the late winter of 1971,  and one that premiered in Durango, CO,  in 1972 (not ’81 as this youtube site claims)1:

Mountain Skywater!

It was SO EXCITING being a part of this grand project!  And who wouldn’t love Durango, Colorado?

But, it turned out that there were lots of problems with the Colorado experimenters hypotheses, and those problems weren’t getting outside of the BuRec and our group.  The wider weather modification community, which so highly regarded the experimenters’ experiments so highly,  remained ignorant of those problems.

Well, during the five years I worked on that project, moved back to “Assistant Project Forecaster” when the second one, Owen Rhea, left after one season and a new Project Manager brought in his own forecaster.

It was later in those five years in Durango with the CRBPP that I abandoned my original Master’s Thesis at San Jose State on southern Cal rainfall trends, and took on  reanalyses of cloud seeding experiments, something that was to go on for the next 35 years or so as “non-funded work”;  weekends, and evenings, mornings before the regular work day at the U of WA.  I was even drafting my own figures in the manuscripts I produced!

I was consumed, as I have been lately, by the lack of reporting, and even false claims in a journal article relative to our CRBPP project in those Durango days, by authors who knew better.   It was truly melodramatic, but I felt someone had to do something about this!

As a cloud watcher, one of the very main things missing from the experimenters’ claims, was the presence, for hours at a time,  of thick, non-precipitating clouds, ripe for seeding, with tops > -23°C, very cold ones.  Instead, the clouds impacting Durango and the surrounding mountains were full of ice, as any cloud watcher could see.  There was no such cloud as the experimenters had inferred via statistical analyses.

Cloud seeding they wrote, had not INCREASED the intensity of  snowfall in their experiments they reported, but must have made it fall from clouds that did snow naturally until seeded. The only evidence they had for the existence of such clouds was that it had snowed longer on seeded days than on control days.

Not only that, seeding had made them snow at exactly the same rate as natural snowfall.  It was a huge red flag for a storm bias in their experiments,  a “lucky draw” or “Type I Statistical Error” for the seeded days.

And that’s what had really happened, among many other pitfalls, as you will read in the linked “review” above.

In conclusion:  you can do a lot over a LONG period when you’re worked up about something!

The End

 

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1Yes, it was a cloud seeding experiment so important, so much optimism around,  it had its own movie!  And it had a score by local guitar master, Clarence “Gatemouth” Brown!

 

 

An interesting day from a cloud modification standpoint, one that doesn’t happen very often

Every once in a great while, we have days where fairly thick clouds do not produce even a sprinkle, even though their tops are a little below  freezing, but not quite cold enough for natural ice to form.  Yesterday was one of those days.

And it was a day you, a cloud maven junior member,  could likely have done something about it:  rented a small plane or helicopter capable of flying up to around 15,000 kft ASL,  taking a bag of commercially available dry ice pellets, then drop them into the fattest, highest Cumulus tops you saw while nipping them in VFR flight mode, and, “violet!”,  ice would have formed along the path of the falling dry ice pellets!

So what were the ingredients that  made yesterday so special for a little renegade cloud seeding?

The clouds that did not rain were pretty thick for ones that didn’t rain naturally, maybe 5,000 to 6,000 thousand feet thick in their maximum “overshooting” tops, and temperatures at top were a little below freezing, but warmer than -10° C.  At lower top temperatures ice would likely have formed naturally.  Here’s the annotated TUS sounding from yesterday afternoon from IPS MeteoStar:

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The 00 Z (5 PM AST) rawinsonde from TUS, typically launched about 3:30 PM AST. The upward pointing arrow shows what the in-cloud temperature would have been like. The lapse rate, from aircraft measurements is virtually never along the “pseudoadiabatic temperature line (one of which is where the horizontal arrow heads are), but somewhere between that and the dry adiabatic temperature lines that show the temperature drop in a rising dry parcel of air (one of which is where the upward pointing arrow begins). Cumulus protrusions carry the boundary layer air from the surface, that air that forms the Cumulus clouds, into the stable,, and warmer overlying air. So, protruding tops sink like a stone; don’t stay long at their lowest temperature, also hurting the chances that ice will form. That’s why you have to do it.

Here’s how it works:  the dry ice pellets, themselves at -72° C, will chill the air it comes in contact with to -40° C, resulting in the formation of jillions of tiny ice crystals in each pellet’s wake, which are then spread over a wider region in the following minutes due to turbulence in the cloud.  In essence, each pellet is creating a tiny,  vertical “contrail” in that cloud, as least in those upper parts of the cloud below freezing.  (Bases yesterday were a little above freezing, around 2° C, while the highest afternoon tops locally appeared to run between -5° and -10° in clouds that were forming in more haze and smoke than usual (wonder if you noticed that?)  Haze and smoke tend to reduce droplet sizes, and in doing that, make it harder to form ice and rain, especially in marginal clouds for that, such as we had yesterday.

What happens next is that the “supercooled” water in the cloud evaporates around those crystals due to the dry ice bombardment, while the crystals take up that evaporated vapor.   When the crystals get large enough, they may collide with some remaining cloud droplets, if there are any around.  Usually all those crystals that have formed will not left too many droplets in their vicinity.

As the crystals grow in size, and because they are in such high concentrations, they will bump into one another and form clusters of ice crystals we call snowflakes.    Cloud Maven Person has, along with Professor Doctor Lawrence F. Radke, the latter the  “Flight Scientist” in those days with the University of Washington Huskies’ Cloud Physics Group1 in the late 1970s,  made snowflakes the size of pie plates (fluffy light ones without a lot of water content) in Cumulus clouds like yesterday’s here.

IMO you would have created not something of much importance, but rather just an annoying sprinkle or very light shower for those out hiking,  horseying around on their horses, biking the trails,  on an otherwise perfect day for outdoor activities.

One of the problems, long known about in such seeding experiments as could have taken place yesterday, is that the cloudy air is moving THROUGH the cloud, exiting at the downwind location.  That is, lower clouds in particular, move SLOWER than the air itself2.

So, you drop some dry ice in a nice turret, the air you dropped it is, along with that turret’s air, will be moving downwind and is going to go out into clear air eventually.    So, if the crystals don’t stay in a turret and upward moving air, but goes out the side of the cloud or into “shelf clouds” like yesterday, those crystals/snowflakes aren’t going to grow much, and will remain “light and fluffy” even though they could be huge because they are like “powder snow” not a lot of water mass in them.   When they melted at cloud base, they might end up being just drizzle-sized drop (less than 500 microns across) or very small raindrops.  So, that’s why you would likely have gotten just a sprinkle or very light rain shower had you done some unlawful, renegade cloud seeding yesterday.  Remember, just like when you hike in the State Land Trust areas, you need a permit to seed legally.

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Yesterday’s clouds

7:02 AM. Tall, but not so tall as to form ice, Cumulus clouds boil up off the Catalinas. Made you think some Cumulonimbus clouds might form later on. They didn't.
7:02 AM. Tall, but not so tall to form ice, Cumulus clouds boil up off the Catalinas. Made you think some Cumulonimbus clouds might form later on. They didn’t.
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10:26 AM. Disorganzied Cumulus still lurking on on the Catalinas, but the main thing here is how much smoke was in the air when you might have been expecting a very clean morning due to the previous evening’s thunderstorms and rains. Very upsetting to this smoky scene.
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10:27 AM. Looking NE at some Cumulus congestus, no ice evident from this view, but I would not rule it out, Forgot to check radar to see if there was an echo with this cloud.
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2:10 PM. By mid-afternoon skies started to look a little threatening with a Cumulus congestus having formed over and extending downwind from the Tortolita Mountains.
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2:14 PM. Looking for ice to appear in the oldest top portions, now evaporating, top of photo. None seen.
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2:39 PM. Someone needs to get up there on top of this Cumulus congestus, drop a little dry ice in it. Nothing came out, though I thought I would feel a drop at any moment! Some sort of birds can be seen, lower right.
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3:19 PM. Looking downwind at part of the base of this Cumulus congestus cloud line that sat over Catalina for awhile. The top has the base, to the left is the “shelf cloud of Stratocumulus spreading out from other tops and drifing downwind. If precip falls out of the shelf cloud, once part of a turret, you can see I hope that it would fall out of a thicker column of dry air.

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4:01 PM. The scene before a lot writing appears on this photo.
The same photo with a lot of writing on it.
The same photo with a lot of writing on it.

The weather way ahead

While warm weather returns to AZ over the next week to12 days or so, there is now, and this goes with climo, a big trough that barges into all of the West Coast in two weeks.

When I say climo, I mean that there  is a noticeable tendency for this to happen in mid-November in the longterm upper air records so that in some areas of California, for example, there is a modest increase in the chance of rain in mid-month over other times in the month.  These kinds of things in weather are termed, “singularities” like the supposed, “January thaw” back East.  This mid-November annual trough passage may be related to the increasing speed of the jet stream in the Pacific as winter approaches, something that changes the spacing between the troughs.  Pure speculation.

But in any event, be on the lookout for a major change in weather here between the 17th and 20th of November.  Something like this is starting to show up in the models.

The End

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1Later renamed the Cloud and Aerosol Research Group.

2Something that was  even noticed in small tradewind Cumulus in the Pacific in the 1950s by Joanne Malkus (later, Joanne Simpson) and her colleagues.

Cumulus congestus cloud grows into a Cumulonimbus over Sutherland Heights! 0.45 inches falls in 20 min after transformation!!

Also, I am also posting way below a new (!) not-previously-published. but rather rejected- by-important-scientists-a-long-time-ago-manuscript FYI!

Very exciting! (Hah!)

Its published now, though, isn’t it???!!!

“Online.”

Its about science and how it works, and how it has failed;  examples given.   I put it down toward the bottom of a normal blog because I am shy.

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Clouds from a few days ago, August 26th, now that the “choke point” in uploading photos to Word Press  has been, at least temporarily ameliorated.

Here’s the sequence as a great cloud bottom drifted toward us from Pusch Ridge on the afternoon of the 26th.  If you saw this coming, you should have been clearing channels around the house for excessive water flow.  I forgot to.

Unloaded 0.45 inches at this site. 1.69 inches up on there on ol’ lady Lemmon. We sure needed this dump! Below, one of the great cloud bottoms of our time, that of a Cumulus congestus cloud, filled, as we say here, with rainy portent (maybe hail, too):

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1:44 PM, August 26th. Note just a tinge of shading on the right side. First drops, the biggest ones, or even hail stones are just coming out.
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1:48 PM. Cloud beginning to bust open with rain now; updraft collapsing over there. Now its a Cumulonimbus.
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1:53 PM. Nice shafting over there, but will the  cloud base overhead now split open  over us?
1:54 PM. Looks really good almost overhead toward Saddlebrooke! Just don't unload after you go by!
1:54 PM. Looks really good almost overhead toward Saddlebrooke! Just don’t unload after you go by!  Note scruff of lower cloud (called, “pannus”) caused the the outflows of storms to the SW of Catalina.  Not long enough really to be a “arcus” cloud, but clouds like this are almost always associated with a shift in the winds that helps build clouds overhead by acting like a micro-cold front, the rain-cooled air lifting the warmer, humid air ahead of it, and some of that warmer air being cooled to its condensation point producing these lower shelves of cloud.
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2:07 PM. The height of the storm, the visibility down to a hundred yards or two is all. This particular intense period hardly lasted a couple of minutes before it let up noticeably.

 

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Pedagogical or possibly, pedantic (boring) module

Update alert for the posting of new (!) not-published rejected items by this Arthur:

The Cloud Seeding Literature and the Journal Barriers Against Faulty Claims:  Closing the Gaps

(the original title, submitted first in 1997), final rejection in 1999 (Bull. Amer. Meteor. Soc.)

The reviewers, Harold O., Danny R., and someone named “Anonymous Reviewer B”, guessed as, “”B”, for “Bernie S.”

Those in the cloud seeding culture don’t need the names spelled out.  Harold O. is part of the “old guard” cloud seeding culture, while Danny R. is part of the new cloud seeding guard, one that has gone on to be a science superstar since his early work at the Hebrew University of Jerusalem under the leader of the Israeli cloud seeding experiments.   He  did some work there on the clouds of the Mediterranean and satellite interpretations of them (available in Hebrew only the last time I checked).

While Danny R was there during the time of the reporting of the benchmark Israeli 2 randomized experiment by the leader of the experiment  (1976-1986) he himself was not involved in those (ultimately flawed) analyses.  Later, he participated in the unraveling of the 2nd experiment with Israeli statistician, K. Ruben Gabriel in 1990, J. Appl. Meteor.  Half of the 2nd experiment’s results had been previously omitted, an omission which produced an apparent, unambiguous “confirmatory” success of the Israeli 1 experiment, for the short of it.

The 1990 development in Israel, in essence a retraction of what everyone thought was an unambiguous cloud seeding success, plus the fall of the equally important, earlier benchmark randomized experiments in Colorado, at one time also claimed to have proved cloud seeding by the National Academy of Sciences (Malone et al 1973),  were the primary reasons for composing the piece being posted today.  You may also know that your very own Catalina  “cloud-maven” was in Israel in 1986 for 11 weeks, in doubt of those “hard-to-rain” clouds that were being described by the leader of those experiments, resulting in “Rain from Clouds with Tops Warmer than -10° C in Israel”, (1988, Quart J. Roy. Meteor. Soc.).  This was to some degree the first crack in those experiments.  (Of course, I would say that!)

How could such glowing,  but ultimately critically flawed journal papers appear ultimately involving hundreds of journal pages?  What went wrong with peer reviews?

I attempt in this piece to describe in this piece how science is supposed to work, and these pretty amazing chapters of science in cloud seeding,  and offered some possible solutions.

At one time, Prof. Peter V. Hobbs, named to write up a status piece on Clouds-Climate for the World Meteorological Organization (WMO) in 2003 or so, was going to use the “rise and fall” of the Colorado and Israeli experiments  in this piece I have just posted.  He was going  to demonstrate how we scientists can think we have proved something,  but upon closer inspection, find that we have not proved at all!

Peter Hobbs was concerned that the then many unknowns about clouds were not being treated properly in climate models (being parameterized too crudely), and therefore those parameterizations of clouds in climate models could  lead to erroneous conclusions concerning the amount of global warming that might be ahead.

In his take on this MS, and that “rise and fall” section in particular, Peter, who was not one to dole out compliments very often said of it, “This is pretty good.”  Peter had not reviewed it beforehand.

Ultimately, Peter contracted pancreatic cancer and was unable to submit his status summary to the WMO.

Some recent clouds I have known; updating “not pubbed” list

7:21 PM, August 13th. A sky so full of portent that evening after a clear day. This our last chance for rain for quite awhile, but Sutherland Heights and Catalina whiffed on this incoming complex of thunderstorms.
7:21 PM, August 13th.
A sky so full of portent that evening after a clear day. This our last chance for rain for quite awhile, but Sutherland Heights and Catalina whiffed on this incoming complex of thunderstorms.  But, we had a fabulous light show from a cell that developed almost overhead, pf Sutherland Heights as dark fell, but a little to the SE, dumping heavy rains in the Romero Canyon/Pusch Ridge area.
7:16 PM. A very dramatic looking shelf cloud spread across and otherwise completely clear sky that evening providing a great sunset photo op.
7:16 PM., August 13th.    A very dramatic looking shelf cloud (Stratocumulus) spread across and otherwise completely clear sky that evening providing a great sunset photo op.  Northerly winds of 25-35 mph and a temperature drop of about 10 degrees accompanied this scene.
6:57 PM. The churning, roiling motion of this turret was remarkable, almost like time-lapse there was so much of it. That easily seen churning was evidence of how unstable the atmosphere was this day, unusually cool for summer at 20, 000 feet or so leading to a strong drop in temperature from the 100 F or so here. which results in the warm air that clouds represent being more buoyant than usual, a hotter than usual hot air balloon, if you will, one that goes up faster.
6:57 PM. The churning, roiling motion of this turret was remarkable, almost like time-lapse there was so much of it. That easily seen churning was evidence of how unstable the atmosphere was on this day.  It was unusually cool for summer at 20, 000 feet or so  above us. leading to a strong drop in temperature from the 100 F or so at the ground.   So, as the warmer air that clouds represent relative to their surroundings, made them more buoyant than usual as they climbed upward;  a hotter than usual hot air balloon, if you will, one that goes up faster.  Stronger updrafts are thought to lead to more lightning compared with Cumulonimbus clouds having weak updrafts.
3:57 PM, August 13th. Even slender clouds could shoot up and reach the "glaciation level", and sent long plumes of ice out. The long trail of ice shows how much the wind increased with height at the top of this cloud. As that evening's storm approached, all of the anvils from the many Cumulonimbus clouds were mostly kept from view so that you couldn't see them.
3:57 PM, August 13th. Even slender clouds could shoot up and reach the “glaciation level” where the tops became comprised of only ice crystals,  and sent long plumes of ice out from the parent cloud. The long trail of ice shows how much the wind increased with height at the top of this cloud. As that evening’s storm approached, all of the anvils from the many Cumulonimbus clouds that were approaching were mostly kept from view so that you couldn’t see them.  This cloud also poses a naming enigma.  Its got an ice plume, a very little rain fell out on the left side where Pusch Ridge begins, but no shaft is visible.  It can hardly be called just a “Cumulus” cloud, and yet the more accurate label, “Cumulonimbus” with all of its attributes, makes one a little uncomfortable due to the lack of a visible shaft.

 

The End (of the cloud discussion)

New “not pubbed” item:

I’ve added RViewpoint_10-24-06_submitted date Aug 31, 2006_final, something that’s been sitting around for years!   Spent a lot of time writing it, but ultimately deemed it a hopeless task that it would be published in the Bulletin of the American Meteor.  Soc. under then current leadership in the weather modification domain of that journal, and ultimately never bothered to submit it.  I was sick of the conflict, for one thing.   Haven’t read this piece in years, either, but just wanted to do SOMETHING with it so here it is on this blog.

A longer piece, “Cloud Seeding and the Journal Barriers to Faulty Claims:  Closing the Gaps“, also worked on again in spare time at home, for about two years, with the final rejection in 1999 under pretty much the same Bulletin editorial leadership.  In this MS, I had a chance to get in, but the specific reviewer whose demands the Editor said I had to meet, insisted that I indicate in the manuscript that the lead scientists in the faulty published reports I wrote about “did the best they could under the circumstances” in the  two early benchmark experiments, those in Colorado and Israel.  I knew from direct personal experience that wasn’t true;  I couldn’t write such a bogus statement that might have made the difference in “getting in.”  So two years of on and off effort went down the drain.  Sometime soon I will add this second futile effort to the “not pubbed” list!  I have a number of those…..  It didn’t help either that the two leading scientists whose work I questioned were also the two most beloved scientists in this field.

As with all but one of these pubs (Hobbs and Rangno 1978) in the domain of weather modification, they were done at home, outside of grant funding work while I was at the University of Washington in the Cloud and Aerosol Research Group.  And, as I sometimes alert audiences to, working at home on stuff year after year. thousands of hours involved,  could be considered a “crackpot alert”.  Well, I think of myself as a “good crackpot.”  haha.

About ice-in-clouds and APIPs (or high temperature contrails)

6:55 AM
6:55 AM.  A surnrise glow from receding CIrrus spissatus highlights Samaniego Ridge.  Very pretty and dramatic.

 

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8:19 AM. Forming uncinus, CIrrus that is.  Note trails of precip beginnng to form under these tufts of Cirrus castellanus clouds.
9:06 AM.  Jet contrails begin to show up in a Cirrocumulus cloud.  You know what going to happen....
9:06 AM. Jet contrails begin to show up in a Cirrocumulus cloud composed of supercooled cloud droplets. You know what going to happen….something special for you to log in your cloud diary.

 

9:20 AM.  Another patch of supercooled, very supercooled Cirrocumulus with evidence of a jet contrail.  But, is the jet above or IN the Cirrocu?  TIme will tell.
9:20 AM. Another patch of supercooled, very supercooled for that matter,  Cirrocumulus with evidence of a jet contrail. But, is the jet above or IN the Cirrocu? TIme will tell.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

How cold were those Cc clouds?  See below.

(Begin technical module)

The Tucson balloon sounding for 5 AM AST, November 19th with writing on it.
The Tucson balloon sounding1 for 5 AM AST, November 19th with writing on it.  The height of these clouds was slightly lower in the mid-afternoon, but (as Altomumulus then) were still about -23 C.  As we know, cloud bottoms almost always get lower with passing time because the higher parts of cloud shields are moving faster.

In the mid- -20s C, around -15 F.  Height, about 21,000 feet above the ground here in Catalina.  Hope you got that estimate of cloud height right.

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Continuing…

9:21 AM.  ANOTHER jet streaks by!  This is going to be darn interesting, a rarity, like see a grey parrot in Catalina!
9:21 AM. ANOTHER jet streaks by! This is going to be darn interesting, a rarity, like seeing a grey parrot in Catalina!  The secret about what height the first jet was flying at is beginning to be revealed.  Can you see what’s happening to that first contrail a little below the new one?  This is a great test to see how far you’ve come as a CMJ (cloud maven junior)!

Here’s what happened in the Cirrocumulus cloud layer in yesterday’s special day, a pretty rare one, after the jets flew through it:

9:30 AM.  OK, mystery's over.  Even the average CMJ Joe can see that 1) the jets were IN the Cirrocumulus cloud, and more importantly, the aircraft contrails consist of ice.  Yes, that's right, the passage of the aircraft has caused a phase change from liquid drops to ice crystals, a lot of them.
9:30 AM. OK, mystery’s over. Even the average CMJ Joe can see that 1) the jets were IN the Cirrocumulus cloud, and more importantly, the aircraft contrails consist of ice. Yes, that’s right, the passage of the aircraft has caused a phase change from liquid drops to ice crystals, a lot of them.

 

9:47 AM.  Now those contrails are looking like real and icy Cirrus clouds.  In this case they're called "ice canals" but sometimes, when aircraft are ascending or descending and do this, they make round clear holes with ice in the middle, called "hole punch" clouds.
9:47 AM. Now those contrails are looking like real and icy Cirrus clouds. In this case they’re called “ice canals” but sometimes, when aircraft are ascending or descending and do this, they make round clear holes with ice in the middle, called “hole punch” clouds.

Lessons to be learned from yesterday’s supercooled clouds and the aircraft interactions inside them:

  • Cloud seeding works!  You CAN  make a supercooled, non-precipitating cloud produce a little precipitation that would not otherwise have occurred.

But in those situations where the clouds, say, are topping the Catalinas, they are often quite thin, and whether there is an economically worthwhile amount of precip is not known.  However, an experiment targeting those clouds would be the perfect “baseline” one in cloud seeding to establish how much we can wring out of non-precipitating clouds.   Things become kind of a mess when even randomized seeding takes on already precipitating clouds.

  • “Overseeding”,  as here in these clouds when aircraft produce prolific numbers of ice crystals in a small volume,  it leads to tiny ice crystals with low  fallspeeds.  Sure, they fall out and leave a hole, but they virtually never reach the ground except in one a in billion cases when the very cold clouds are real low, practically on the ground.
  • The Wegener-Bergeron-Findeisen mechanism produces precipitation.

Alfred Wegener, 1911, and  later Bergeron3 and Findeisen in the 1930s, came up with the hypothesis that adding ice to a supercooled cloud results in the growth of the ice crystal at the expense of the droplets.  They’ll tend to evaporate while ice is being added to the crystal via deposition of water vapor that was once liquid.  So, an awful lot, maybe most of the precipitation that falls on earth, involves “mixed phase” clouds.  This process has also been called the “cold rain process.”

However, let us not forget the two other processes that produce precipitation, the all ice process (no liquid required–helps produce “powder snow”, and the all liquid process, where cloud drops collide and grow into raindrops–the biggest measured drops in the world (about 1 cm in diameter) have formed soley through this process.  It is likely that most of the rain that falls in tropical locations like the Hawaiian Islands and in hurricanes is due to this process even when ice is present in the top part of storms.

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Later, we had some Altocumulus castellanus clouds with virga as the moist level lowered, though they were long gone before they could provide us with a nice sunset:

2:32 PM  Bands of Altocumulus castellanus approach from the west.  These clouds, while based at just about the same level as the Cirrocumulus clouds earlier in the day had three things going to produce so much ice, and really, convert to Cirrus clouds.  The cloud bases were slightly warmer, meaning more water was available to the cloud, the tops were higher and colder, likely around -30 C (-22 F), and perhaps as importantly, the drops near the top of the Ac turrets were larger than those in the earlier Cc clouds.  The larger the droplets, the higher the temperature that they freeze at.
2:32 PM Bands of Altocumulus castellanus approach Oro Valley from the west. These clouds, while based at just about the same level as the Cirrocumulus clouds earlier in the day had three things going for them to produce so much ice (right side of photo–and really, convert to Cirrus clouds).   The cloud bases were slightly warmer (the TUS sounding suggests, -22 C), meaning more water was available to the cloud, something that would impact the drop sizes in the turrets of the Altocumulus clouds (left side of photo); 2) the tops were higher than the Cc clouds (ones that were paper thin) and therefore,  slightly colder (probably about -28 C)  than those of the Cc clouds,  and perhaps as importantly, the drops near the top of the Ac turrets before they converted to ice, were larger than those in the earlier Cc clouds. The larger the droplets, the higher the temperature at which they freeze.  So, ice is more likely to form in a cloud with larger droplets in it than one with tiny droplets in it even though they are the same temperature.  That might explain the difference ice-forming behavior of yesterday’s very thin Cc clouds which mostly had no ice (until an aircraft came along in them) and these prolific ice-producing Altocumulus clouds, ones that converted to all ice.  Just educated guesses here.

 

Still looking for scattered very light showers in the vicinity tomorrow as a Mr. Troughy goes by.

The End.

——————————————

1Through the oral history tradition I learned while viewing the Washington Husky meltdown2 at AZ stadium on Saturday from a Mr. Mark Albright that the Tucson weather balloon launch site has been moved from Davis-Monthan Airbase to the University of Arizona campus next to their weather department.

2Late in the proceedings, with about 2 min left and the Huskies starting a play, and in the lead, CM was visibly  moved to jump up and say, “Don’t hand the ball off!”, as a gift to Arizona fumble occurred simultaneously.  But, being bifurcated in his loyalties now that CM is in Arizona and not with the University of Washington, he had to be somewhat “glad” that the Cats maintained their somewhat suspect but great win-loss record.

3From the Historic Moments in Weather collection:

Tor Bergeron and CM meet in Goleta.  His head was gigantic!  No wonder he was so smart.  CM, not so much.
Your Catalina CM and Tor Bergeron meet for the first time in Goleta, CA, in 1968 at the headquarters of North American Weather Consultants. Yours for $2,100 dollars, today only.   I remember thinking that his head was gigantic! No wonder he was so smart. CM, not so much.

Dull cool day and blog, book-ended by a nice sunrise and a nice sunset

Here we go…..some pretty, but also dull,  photos, along with some novella-sized captions as mind wandered into the obtuse while writing them.

6:44 AM.  Nice sunrise due to  Altostratus/Cirrus ice clouds.
6:44 AM. Nice sunrise due to Altostratus/Cirrus ice clouds.
2:00 PM.  Stratocumulus topped Samaniego Ridge most all day, but was too warm to have ice, and droplets too small to collide, stick together, and form misty drizzle. Misty drizzle?  Could be a great name for a late night female vocalist.
2:00 PM. Kind of a dull day yesterday, kind of like this blog.  Stratocumulus (Sc) clouds  topped Samaniego Ridge most of the day, below that gray Altostratus ice cloud layer.   But those Sc clouds were too warm to have ice in them, and droplets were  too small to collide, stick together, and form misty drizzle.  Have to get to at least 30 microns in  diameter before they stick to one another.  Misty drizzle?  Could be a great name for a late night female vocalist doing earthy songs like Earthy Kitt back in the ’50s.  “Earthy” was much hotter than global warming.
3:29 PM.  An Altostratus translucidus mostly ice-cloud with a dark patch of Altocumulus droplet cloud blocking the sun.  If you look closely, you can see a that there's this Altotratus layer may be topped by a Altocumulus perlucidus droplet cloud layer.  Yes, droplet clouds at the top of As where the temperature is lowest?  Yep, happens all the time, up to about -30 --35 C.    Been there, done that, in aircraft research.
3:29 PM. An Altostratus translucidus to opacus,  mostly ice-cloud with a dark patch of Altocumulus droplet cloud blocking the sun. If you look closely, (upper center) you can see a that there’s this Altotratus layer may be topped by a Altocumulus perlucidus droplet cloud layer. Yes, droplet clouds at the top of As where the temperature is lowest? Yep, this counter-intuitive finding happens all the time, up to about -30 C -35 C. Been there, measured that;  in aircraft research.  Ma Nature likes to form a drop and have it freeze before forming an ice crystal directly from the water vapor.
4:40 PM.
4:40 PM, shot taken as we entered a local restaurant.  You’ve got your two layers of Altocumulus, with some Altostratus translucidus above those, filling in the gaps.  Gaps?  Huh.  I am reminded that I have a failed manuscript about “gaps”, these kind;  Cloud Seeding and the Journal Barriers to Faulty Claims:  Closing the Gaps., rejected by the Bull.  Amer. Meteor. Soc. way back in ’99.   It was an instruction manual,  in a sense,  about how to prevent all the bogus cloud seeding literature that got published in the 1960s through 1980s, and was not only published, but cited by our highest national panels and experts, like the National  Academy of Sciences.   Amazing, but true.  I give examples.   You can read about this chapter of  science in Cotton and Pielke, 2007, “Human Impacts on Weather and Climate”, Cambridge U. Press, a highly recommended book.  That cloud seeding distortion of cloud seeding science was due to many factors, of which perhaps the primary one was, “nobody ever got a job saying cloud seeding doesn’t work1.”  This was a great segue.  Of course, we have similar stresses on those researchers looking for effects of global warming nee “climate change” now days.  Nobody will ever get a job (a renewed grant) saying they can’t  find evidence of global warming, “Can I have some more of that money to keep looking?”  And beware the “Ides of March” if you criticize published work in that domain!  Think of poor Judy C , a heroine to me, and how she’s been vilified for questioning climate things.

 

DSC_0076
5:29 PM, took leave from Indian food there in R Vistoso for this.  Its not just anyone who would excuse himself from dinner to do something other than visit the laboratory.

That’s about it.  No use talking about the rain ahead again.  Seems to be a couple chances between the 20th and the 30th.

The End

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1You can make a cloud snow a little by seeding it with dry ice or silver iodide.  This has been shown since the earliest days of experiments.  Below, to demonstrate this, an aircraft inadvertently “seeded” this Altocumulus cloud layer.   However, whether the small amount that falls out from previously non-precipitating clouds is economically viable is not known.   Increasing  precipitation due to seeding when the clouds are already snowing/raining  has not been satisfactorily proven.  As prize-winning stat man, Jerzy Neyman,  U of Cal Berkeley Golden Bears Stat Lab would tell you, you need a randomized experiment and followed by a second one that confirms the original results, with measurements made by those who have no idea what days are seeded and evaluations done by those who have no vested interest in cloud seeding.   Wow there’s a lot of boring information here.  Getting a little worked up here, too.

Ice canal in supercooled Altocumulus clouds, bases -23 C, tops -25 C (from PIREPS).
Ice canal in supercooled Altocumulus clouds over Seattle, bases -23 C, tops -25 C (from PIREPS).  Photo by the Arthur.

Encore of disappointment

Yesterday afternoon and evening were remarkably similar to the day before;  great, spectacular banks of brilliant white turrets with black bases approached from the northeast filled with rainy portent, but, as with that previous day, disappointed.   Once again, those clouds tended to fade some as they much beyond the Catalina Mountains, southwestward across Catalina, Saddlebrooke, and Oro Valley.  Even the rainfall here in Sutherland Heights, 0.08 inches, was almost identical to the day before!

While there were many similarities, one had to be hopeful looking at those clouds as they spread across the valley.  They many more Cumulus turrets above them compared with the prior day, had not faded completely to flat stratiform clouds riding an outflow wind.  In fact, if you noticed, as they encountered the warmer air to the west of us, ramped up into major storms around I-10 and farther west.  They are still going strong, now, a little before 4 AM, approaching Puerto Peñasco/Rocky Point!   (This is a peak time of day for rain in the Colorado River Valley, oddly,  spanning Yuma to Needles since many of our evening storms here continue on to that area during the night.)

Models still have lots of rain in our future as tropical storms whiz by in the Pacific west of Baja over the next 5-10 days (models have, not surprisingly, backed off direct Arizona hits for now1).  Still there’s plenty of time and water in the air to catch up on our normal summer rainfall.  At 4.58 inches, we’re not terribly behind the six inches expected in July and August in Catalina, and with recent rains, the desert has rebounded in a satisfying green over the past couple of weeks.

From the afternoon of August 16th.
From the afternoon of August 16th.  Anyone for “cactus golf”?

Of course, it you were up early yesterday, you may have seen the lightning (LTG) to the south through southwest.  We missed a nice complex of heavy rain that brought 1-2 inches in a couple of spots as it passed across Tucson and into the Avra Valley.

Your cloud day

6:32 AM.  Miniature arcus cloud leads the way ahead of those heavy Tucson rains.
6:32 AM. Miniature arcus cloud leads the way ahead of those heavy Tucson rains.  At the leading edges, many of those clouds would be called, Altcoumulus castellanus, mid-level clouds with spires.  But sometimes they cluster, as yesterday into clouds too large to be “Altocumulus” clouds, but rather Cumulonimbus ones with mid-level bases.
7:03 AM.  Rain continues to move westward into Avra Valley and Marana.
7:03 AM. Rain continues to move westward into Avra Valley and Marana.  Note crepsucular rays shining down on Rancho Vistoso or someplace like that.  There are quite a few “Vistosos” around it seems.
7:36 AM.  I loved this little guy, all by itself of up there, trying to do the best it can to be something.  Such a pretty scene if you can avoid the snail implication.
7:36 AM. I loved this little guy, all by itself of up there, trying to do the best it can to be something. Such a pretty scene if you can avoid the snail implication.
2:05 PM.  Of course, the Cloud People like me always want to document "First Ice" of the day, and here it is in this sprout off the Catalinas.  Can YOU see that critical aspect of our clouds in this shot, one not taken while driving, of course?
2:05 PM. Of course, the “Cloud People” like me always want to document “First Ice” of the day in his/her cloud diaries, maybe mention it to neighbors later, and here is that moment for yesterday afternoon in this sprout off the Catalinas. Can YOU find that critical aspect of our clouds in this shot, one not taken while driving, of course?  Remember, almost always in Arizona, clouds need ice to rain.
4:44 PM.  As predicted in the U of AZ model, great banks of Cumulus and Cumulonimbus clouds roar down from the Mogollon Rim and other high terrain to the northeast of Catalina with the promise of a substantial rain.  Looking N across Sutherland Heights and Saddlebrooke
4:44 PM. As predicted in the U of AZ model, great banks of Cumulus and Cumulonimbus clouds roar down from the Mogollon Rim and other high terrain to the northeast of Catalina with the promise of a substantial rain. Looking N across Sutherland Heights and Saddlebrooke
5:36 PM.  Incoming Cbs (Cumulonimbus clouds) getting really close, but cloud maven person forgets to look up and in a couple of minutes, giant drops are falling by the millions.  Kinda reminded me of that time at the Mitchell, SD, airport in '72 when I was radar meteorologist on a project having four aircraft that were to be sent up to try to prevent hail by "overseeding" them with silver iodide.  Well, it was midnight or so, and the radar can't look up, but rather out, at storms to send the planes toward, and the 1-inch hail stones started pummeling the airport from a cell that developed overhead, like that one yesterday afternoon did over Sutherland Heights!
5:36 PM. Incoming Cbs (Cumulonimbus clouds) getting really close, but cloud maven person forgets to look up and in a couple of minutes, giant drops are falling by the millions. Kinda reminded me of that time at the Mitchell, SD, airport in ’72 when I was radar meteorologist on a project having four aircraft that were to be sent up to try to prevent hail by “overseeding” them with silver iodide2. Well, it was midnight or so, the radar can’t look up, of course, but rather out, at storms to send the planes toward. Well, the 1-inch diameter hail stones started pummeling the airport from a cell that developed overhead, like that one yesterday afternoon did over Sutherland Heights!

 

5:41 PM.  Surprise!  Extra big drops, too, for a brief time, and 0.06 inches.  It was so fantastic!
5:41 PM. Surprise! Extra big drops, too, for a brief time, and 0.06 inches. It was so fantastic, as unexpected rain always is!

 

6:02 PM.  Its looking "oretty good" here, a couple of expansive, solid dark bases.  But, there are also those "weak" updraft updraft areas denoted by broken light and dark areas.
6:02 PM. Its looking “OK”, better than the day before here,  with a couple of larger, solid dark bases. But, there are also those “weak” updraft updraft areas denoted by broken light and dark areas. Nice lightning on the left;  lighting on the right.

 

6:37 PM.  While one of those bases unloaded with a few cloud-to- ground LTG strikes  over there by the Palmer in Sutherland Valley, the base to the north of us just could not work its way S, and unloaded
6:37 PM. While one of those bases unloaded with a few cloud-to- ground LTG strikes over there by the old Golder Ranch  in Sutherland Valle. The bases to the north of us just could not work thier way S, and pretty much remained in place, unloading on Charouleau Gap

 

6:49 PM.  Hopes for a substantial rain fading fast as the cloud base this side of the Charouleau Gap rain area began to look chaotic.  The rain that's falling there needs to be replenished by new turrets that convert to ice, and if that's not happening, then the rain just falls out and the storm ends.  Here, that rainy area was just not replenished by building turrets, and so got lighter and lighter until it faded away.
6:49 PM. Hopes for a substantial rain fading fast as the cloud base this side of the Charouleau Gap rain area and estedning overhead of Sutherland Heights began to look chaotic, not firm and smooth. The rain that’s falling on the Gap needs to be replenished by new turrets that convert to ice, and if that’s not happening, then the rain just falls out and the storm ends. Here, that rainy area was just not being replenished by building turrets adjacent to it, and so it got lighter and lighter until it faded away. Also, the rain shafts never had that black, straight sided look that goes with strong convection.

 

7:03 PM.  Rosy glow at sunset...yet another great name for a western singer!  But, getting back on task,  notice the rain shafts and how wispy they are, with sloping rain.  That indicates the tops aren't too high, the updrafts weak, and the clouds probably just barely made it to the ice-forming level.
7:03 PM. “Rosy glow” at sunset…yet another great name for a western singer! Where do these come from?  But, getting back on task, notice the rain shafts and how wispy they are, with sloping rain. That indicates the tops aren’t too high, the updrafts weak, and the clouds probably just barely made it to the ice-forming level.

 

U of AZ mod run from last evening’s 11 PM AST data indicates a day today like the past two:  coupla small Cumulonimbus clouds on the Cat Mountains by mid-afternoon, then a line of big storms again sweep down from the higher mountains to the NE in the evening.  Maybe today we’ll get that big rain finally.  If nothing else, the skies will be spectacular and dramatic again.

The End.

——————–

1A peak just now at the 11 PM WRF-GFS run shows that the unusually strong tropical storm not so far offshore from San Diego has been resuscitated.  Go here to see this exciting storm and all the rain we’re supposed be getting over the next two weeks.  Getting pretty worked up about it again.
2Does seeding to reduce hail work? The evidence is mixed, and is not convincing to national panels or the American Meteorological Society. Still, that type of cloud seeding is carried out in many locations in the Canadian and US grain belts.

Cirrus at 40,000; a science story about a death prediction

Here they are:

6:44 PM.  Some Cirrus spissatus floated over late yesterday.  When its unusually warm, Cirrus are often unusually high such as yesterday's.
6:44 PM. Some Cirrus spissatus (thicker blobs) floated over late yesterday. When its unusually warm, Cirrus are often unusually high altitude such as yesterday’s.

Still no rain in the two week model “headlights”…and believe me I look for it.

A science story

While we’re waiting for “weather”, I thought I would partially bore you with another science story.

I am supposed to be dead by now, well, within 5-10 years after 2003 due to the development of a rare disease called pseudomyxoma peritonei, resulting from a tumor called, mucinous cystadenoma. Actually, I feel so good today at 71 years of age, doing more weight at the gymnasium than I ever have in the past 16 years on some machines, I tell friends that it must be a pre-death “bloom.”

But back in August of 2003, I left work with an incredible gut pain and ended up in the ER at the University of Washington’s hospital, never having finished that afternoon cup of coffee. After a day or so of monitoring, the doc there, Mika Sinanen, “went in” with his team.   It wasn’t presenting as a classic appendicitis.  He found a tumor exiting the appendix. He had never seen this before, and didn’t know what it was.

Later, while in his office, the pathologist came back with the report on it.  It was a “mucinous cystadenoma”, not cancerous.  But SInanen wasn’t as excited as I thought he should be that it wasn’t cancer.   He told me to meet with the University Hospital’s surgical oncologist.

A few days later I was informed by that oncologist that I would likely experience a series of abdominal operations over the coming years due to the development of the disease called, pseudomyxoma peritonei, in which a mucinous jelly like growth attaches to organs in the gut.   There is no cure I was told; portions of the gut are removed, the doc said, until no more can be removed and you die of “blockage.”  It didn’t sound good.

Keep in mind the date of this event, August 2003.

Now the science part.

In September of 2002 a farmer from west Texas was upset over a cloud seeding program his county was going to undertake and had decided to write to all of the universities having atmospheric science programs about the status of cloud seeding. Was it proven? And would it work in the summer clouds of west Texas?

He eventually reached me at the University of Washington. I had published critiques and reanalyses of cloud seeding experiments in peer-reviewed journals, usually with the Director of our Cloud and Aerosol Group, Peter V. Hobbs, as a co-author, over the preceeding 25 years. In the farmer’s note, he said that he had contacted over 130 universities, and that my name had come up often. I cherish that e-mail even today, an indication that your peers had noticed your work.

I should mention that all of this reananlysis work was self-initiated, and except for one paper, they were done off and on on my own time with no funding whatsoever over a period of about 25 years. I sometimes partially joke about this aspect in introductions of talks on this subject by describing all this self-funded work as a “crackpot alert”. But I was trying to be a good crackpot.

I sent this farmer the fairest objective one-page note on cloud seeding I could, one that I thought my peers would also agree with. Its our job as scientists, even if with think they are still faulty reports out there, we have to cite them until they are officially overturned. I wrote to the this farmer that cloud seeding had not been proven in those types of clouds (summer Cumulonimbus ones) in ways that we in the science community would find convincing. That is, proven through randomized experiments, double blind ones, and in which the results had been replicated. That’s the gold standard for all science. I did point out, as I must as a scientist, that there were “promising results” using hygroscopic methods of seeding of such clouds. That was about it.

Implementing a commercial cloud seeding project creates jobs (don’t forget, the author has participated in these), and it looks good for sponsoring organizations, like state and county governments, to try to do something about droughts. Makes constituents happy even if most academic scientists question such a practice absent proper evidence.

Within 24 h of sending that note, I received this e-mail from Texas:

“You will die in 11 months from a fast-growing tumor, you f…… rascal.”

It was pretty odd since it had a timeline, and that 11 months was odd, and I thought use of the word “rascal” didn’t fit the preceding expletive. Another expletive would have fit better.  There was no way to connect this e-mail to the note I sent that farmer, but the timing made it clear it had something to do with it.

Well, EXACTLY 11 months after that note I was on my way to the hospital leaving a half a cup of coffee on my desk at the U of WA due to an odd tumor exiting my appendix. And, by golly, I WAS going to die, but in 5-10 years!

I will never forget that day the surgical oncologist at the U of Washington hospital told me that. The disease never showed.

I always wanted to write to that e-mail address from where the threat originated (a phony one) and say,
“Hah-hah (emulating “Nelson” on The Simpsons); it was a SLOW growing tumor!”

——————————–

One final note.

Scientists don’t like it when you’re reanalyzing their work, naturally. The very first review I saw of my first paper reanalyzing a randomized cloud seeding experiment was so bad, and had a personal attack that I did not have the credentials to reanalyze that experiment1 it made a fellow, cartoon-drawing graduate student in our group, Tom Matejka, laugh.  He then came up with the image below of how that reviewer must have seen me. His drawing was so perfect a depiction, I loved it.  The paper, “A reanalysis of the Wolf Creek Pass cloud seeding experiment”, was the lead article in the May 1979 issue of the Journal of Applied Meteorology.seeding cartoon of art

I have also included a photo of Tom, one of my favorite grad students passing through our Cloud and Aerosol Group at Washington. You can see the playfulness in his face.

Tom Matejka, circa 1979.
Tom Matejka, circa 1979.

—————–

1True, actually; I had no credentials in that domain at that time.

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.

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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.