Category Archives: Definitions

“Little snowstorms in the sky, I think I’d like to have some pie”

You’re probably smiling now remember singing this little ditty as a kid, maybe singing it with your friends on the bus, whenever you saw “Altocumulus floccus virgae” clouds such as are pictured in the first photo.   Wasn’t it great when you saw these kinds of clouds while on a vacation trip and mom and dad had to stop somewhere to get you some pie after you sang that song?   Well, I nostalgiate here.

To the right of the dead yucca stalk, Altocumulus tufts are shedding snow.  The opacity of the virga is a give away that its snow, and not rain.  In some of these little tufts, the water droplet cloud that preceeded the formation of ice has disappeared, and all that is left is falling snow.  How much snow is it?  Just a flurry, if you were up there, even though it looks pretty thick.  Once in awhile in our research on ice in clouds at the University of Washington, we got to sample these from top to bottom.  Because the ice crystal concentrations are usually pretty low in clouds like the ones shown, a few per liter and often less than 1 per liter, those delicate ice crystals don’t bump into each other much and break up,  and you find gorgeous images of star-like crystals in these fall out streaks, the kind you see on Christmas cards (examples here).   How do I know what from ten miles away and 16,000 feet or so below them.   Its a funny thing, but ice crystals are differently shaped depending mostly on temperature.  To get the temperature of these clouds you can get a pilot report (unlikely) or examine the humidity profile of the Tucson sounding for “00 Z” (5 PM LST yesterday afternoon and make an educated guess.   The highest relative humidity on that sounding was at 525 mb ) about 15-16, 000 feet above the ground) with a temperature of -16 C (about 3 F), namely, darn cold.  Continuing, we in this field have a well known chart by Magono and Lee (1966)  that shows the temperature at which certain forms of crystals grow.   At the temperature I am guessing those clouds were at, those crystals would have grown as stellars and dendrites, which grow between about -12 C and -18 C.  Sometime I will show you some of these crystals, but for brevity will quit here on this topic.

The second and third photos show what one of these tufts looks like before the crystals have grown and fallen out.  Top center, the largest raggedy tuft (Altocumulus floccus) show no fallout of ice.  In the last photo, twenty-nine  minutes later, there is a fine veil of ice crystals below it (upper right hand corner).  Only now, with virga, are they “Altocumulus floccus virgae”!   I’m singing right now!  And, if you look really carefully you’ll see that most of those little guys have a little ice fall underneath them.  Certainly, in those clouds you would find PERFECT crystal specimens!

I’ll end here on an exciting note.  The Enviro Can model CONTINUES to show a very strong system moving into our area on Saturday afternoon, likely accompanied by winds as strong or stronger than we saw last Saturday,  before the rain and cold air hits on Sunday.  Snow levels are going to be really low and we might see some ice in the rain on Sunday here in Cat (alina) Land.  Amounts are looking substantial at this point.  Man, do we need it!

In the meantime, an upper trough off Baja passes over tomorrow.  It has enough moisture with it to provide more “clouds for pies” (Altocumulus floccus virga, and, of course, Altocumulus castellanus virgae, which also qualifies as well for a pie).   And, some cirrus will be around, too.  However, I am going to stick my neck out and say there will be sprinkles tomorrow.  Mods really don’t have a thing, so you’ll have to keep that in mind.

Be sure to keep you’re camera ready for sunsets like last night (see below)!

0.07 inches

It was beginning to seem like measurable rain could not fall again here!  But then those Stratocumulus clouds because closing in in the afternoon, then soon after that some snow virga began to trail down from them here and there, and the next thing, large regions of the sky were suddenly shedding virga and rain at the ground.  Also, as with the day before anmd at the same time, a windshift line moved across the Tortolita mountains and into Oro Valley helping to augment those Stratocu.  Here’s the pictorial record:

Your thoughts at this time: "Look, the clouds are quite thin, and the sun is going to be out soon! It will be a nice day after all." Background: the morning overcast of low clouds has dissipated and you are responding to new conditions.
The lower clouds gradually fatten up on solar calories, and because there is a disturbance aloft approaching that you can't see, the clouds begin grouping into darker regions that cover ever larger portions of the sky. The upper air disturbance is the "conductor" of the cloud "orchestra" and its getting closer to passing overhead at the time of the 2nd photo. However, you may still not be too concerned, but after all, there is no precip drooping down from all these clouds that you now see. BTW, I went into the Tortolitas to get this 2nd panaramic shot looking downwind toward Oracle and the Oro Valley for you (hahaha-just kidding).


Quickfire quiz:  Why isn’t there virga trailing down from those clouds in the 2nd photo, except in the very far away clouds where you can see just a tad????

(Answer, printed upside down if I could):  “They are not cold enough yet to have ice form in them, and ice in clouds is necessary for rain at the ground, as a rule in AZ.”

So those Stratocumulus and some of them are starting to look more like Cumulus clouds at about this time (2nd photo), have to get colder by deepening upward some, and/or colder air must move in aloft to chill them down.

Weird factoid about ice in clouds:   A cloud will form MORE ice for the same top temperature as its bottom gets warmer!  That could be a whole 100 page discussion.  Now, if you’re really pedantic, you can go here to read about all the mysteries that we (those who make a living studying clouds) are going to try to solve in a project in the Virgin Islands this summer, called “ICE-T” here.

In the 3rd and last photo, the nose of the windshift coming across Oro Valley is marked by that highlighted shred cloud in the center of the photo.  It was moving from R to L, undercutting the  higher based clouds that were still moving from the SW.   As you can see by the obscured bases all around, there is widespread areas of rain at this time, augmented by taller clouds with thicker, darker shafts of rain, probably leaning toward a “weak” Cumulonimbus classification if you could see the whole thing.  Note how the distant hills and mountains are obscured in rain.  Yay!

It was after this shot that Catalina got its little amount.


Next “storm” this being 2 of the model foretold six days of rain some time ago?  Wednesday.   However, the mods are unimpressed with the moisture in this and none that I have seen have a drop as this upper air disturbance goes over us.   At the LEAST, we should have some nice Cirrus, and probably Altocumulus clouds.   And you know what that means now….   The possiblity of a trick sunset due to a parhelia (aka, sun dog, mock sun).

Also, I really like the the Canadian model run today that calculated where the highs and lows are going to be for the next several days based on last evening’s weather measurements around the globe.   I really, really like it because it shows  a huge storm here and in the SW six days out.   My preference has nothing to do with objective science.  The models have been fluctuating on how this next storm is going to be, minimal or gigantic, sometimes that’s just the way the models are when there is a lot of uncertainty about things upwind of us. Its one of those that is accompanied by an Arctic blast down the West Coast.  Can’t wait!

The end.


Moist but mostly dry

Though HUGELY disappointing because only a trace of rain fell here as of 7 AM this morning, and only a little in the Canada del Oro wash watershed (amounts here), nevertheless, what a nice, classic  passage of a cold front.  A cold front, as it sounds,  marks the advancing boundary of colder air that is displacing warmer air, and that went went by late yesterday afternoon.  When it goes by, the wind direction changes almost instantaneously, the temperature begins to drop, often sharply at it did at 5 PM yesterday (see below), and the barometric pressure begins to rise.


But without measurements or satellite or other data, you yourself could have seen that invisible boundary approaching Catalina by the low, scruffy clouds that began to appear on the horizon to the northwest.  Soon they were topping the Tortolita mountains, then the Catalinas.    And you would have noticed that, unlike the clouds overhead, those lower clouds were advancing from the north.  That evolving scene looked like this, finally ending up as a low overcast of Stratus clouds.  The first shot below was at 4:40 PM, 20 minutes before the windshift and temperature plummet hit.  The second shot is as the windshift was passing Golder Ranch Drive and shows the lower cloud bases associated with the cooler air racing south along the west side of the Catalinas.   You can see that they are also connecting to the higher Stratocumulus layer.  The third shot shows the Catalinas fully enveloped in the cooler air and lower clouds, and the last shot is of those much lower clouds (I would call them “Stratus”) over Catalina and Oro Valley, looking to the west.

You can also relive yesterday’s clouds and windshift from the vantage point of the University of Arizona’s timelapse film.  You will see the windshift hitting there marked by puffs of dust from the NW and then those low scruffy clouds right behing beginning about 5:20 PM here.

So why didn’t it rain with all these clouds?  What was missing?  For almost every drop of rain that falls in Arizona, ice crystals are required to start the precipitation process going.

The formation of ice in clouds is a continuing scientific enigma, believe it or not.  However, we know that they didn’t form, with brief exceptions yesterday afternoon when a few sprinkles (NOT “DRIZZLE”, dammitall!  Sorry, lost control there for a second)…..formed in the higher deck of Stratocumulus clouds, and again last evening when it rained again for a few minutes.

The first thing you would guess then, since we are talking about the formation of ice in clouds,  is that the tops of the clouds did not get cold enough, that is, were not high enough above us and upwind of us, for ice to form.  That would be my best explanation for those periods where it was not raining, we had low clouds and they looked rather threatening for much of the time between 5 PM and dark.  (After dark, some rain did briefly fall.)

However, the Tucson sounding launched yesterday afternoon around 4 PM shows that the tops were plenty cold enough; the top of the moist layer was about -20 C! (Note:  soundings do not measure “clouds”, but rather humidity, from which we INFER clouds).   Normally a considerable amount of ice would be expected in clouds having a top temperature that low.  Tiny echoes did occur over and downwind of the Catalinas all around the time of that sounding which means that ice was forming precip here and there in the clouds we saw, and measurable precip was recorded in the CDO watershed.

Sure wish I could have been up there in our former research aircraft to check this out more!  But, will have to leave this in a bit of an unsatisfactory way.

My apologies if this got a bit deeper than you really wanted to get into.

Trick and treat sunset yesterday evening

Late yesterday afternoon, the sun appeared to be setting in the wrong location, about 20-25 degrees south of where it is supposed to be at this time of year.  Perhaps something horrible had happened, I thought.  Retirement with a happy ending here in Arizona was too good to be true, I thought, and now it was all going to come to an end.  First, some perspective on where the sun was going down BEFORE yesterday.   This first shot was taken just a few days ago (Feb 13th).  Note where the sun is relative to the Tortolita mountains on the right, and Twin Peaks, the two itty bitty humps to the left.  For further perspective, at the winter’s solstice, December 21st, and from this same location, the sun sets next to Twin Peaks.   So,  in this first shot you can also see how much the sun has moved in two months.

But then yesterday, something awful seemed to be happening.  The next photo was one to send chills down your back, and in fact, if the sun was setting over there in the winter as a matter of routine, the northern hemisphere would likely glaciate down to about Blythe in the winter, due to the NH sunlight being so weak (that is, with so much tilt of the earth’s axis about which it spins).   The days here would, in that case, be about the length of those in Seattle with daylight only from about 8-4 PM in the wintertime because the sun would be taking such a low trajectory in the sky;  would rise late and sink early.

So, while I was concerned with the earth-sun system and some kind of apocalypse yesterday evening, I have feeling that most people were thinking, “Well, I guess we’re not going to have such a great sunset.  Seems to be too many clouds over there where the sun is setting.”

Or maybe you were thinking about that important Washington Husky  Arizona Cats basketball game today and how it might go.

But “No!”, a little later the sun underlit all those clouds, appearing to have sunk in its proper position for this time of year (3rd photo)!

I felt relieved and started thinking about that important Washington Husky -Arizona Cats basketball game today and how it might go.  Then I also started thinking about how I might have been the ONLY person to notice something was terribly WRONG with that sunset.  I feel pretty good about that part.

So, what happened?  This “trick” sunset, followed by a treat of a sunset was caused by a parhelia (explanation by my friend, Bob, here) whose accessible name is “sun dog” or “mock sun”, which we CERTAINLY had in this case!

Parhelia appear, if you don’t go to the site above for a more complete explanation,  when the ice crystals in the cirrus clouds up there are hexagonal plates, and fall with their faces down.   The sun’s light is refracted (bent) as it passes through jillions of these plates and at about 22 degrees from the sun’s position, an observer on the ground will see a bright spot, sometimes with a little coloration.  Sometimes there is also a “22 degree” halo along with the sundog.

I should add that the “trick” parhelia was being produced by ice crystals in the cirrus clouds above and behind the altocumulus cloud deck yesterday.  Of course, as you know, altocumulus clouds are comprised completely or mostly of droplets and cannot, therefore, produce parhelia.

Finally, to end, the last shot is almost at the winter solstice, taken on December 26th, and has a parhelia, aka, sun dog, mock sun, at left so you can see what they usually look like and how far away from the sun they are near sunset.   Yesterday’s, though, I thought was astoundingly bright and really made it look like the sun was going down in the WRONG place.

The end.

First “storm” in the series, a trace of rain!

While taking the dogs out for their daily jaunt over the equestrian trails hereabouts yesterday morning, I was fortunate enough to experience several tiny drops of rain at 7:10 AM.  Rubbed a couple off the dusty car windows to be sure it was happening, it was THAT slight!   It lasted for maybe 15 minutes.  How tiny were the drops?  Oh, maybe 500 microns in diameter, practically “drizzle-sized.”  Recall this is ONLY THE BEGINNING of “stormy weather” in SE AZ, to quote a song title by Harold Arlen and Ted somebody.

What is “drizzle-sized” you ask?   Well maybe you didn’t ask,  but I am going to tell you anyway as part of a harangue about folks mis-indentifying drizzle occurrences.  It happens a LOT even with your local TEEVEE weather presenter (can’t refer to anyone who doesn’t know what drizzle is as a “meteorologist”!)

Drizzle drops are defined by official weather folk who know what they are talking about as those drops between 200 and 500 microns in diameter.  A typical human hair is 100 microns in diameter.  So, they are darn small and have so slow a fallspeed that they appear to float in the air. If you ride a bike, you will know that no baseball cap will keep drizzle drops off your glasses.   The World Meteorological Organization’s description, is “fine, close together drops.” Furthermore, unlike yesterday when those drops were incredibly sparse, drizzle occurrences are often noted by lots of tiny drops in the air, 1os per liter of air if you want a number, which I doubt.  This often causes the visibility to be reduced, but it is also close to saturation in most drizzle, sometimes the visibility is reduced further also by fog.

A common misconception today by those ignorant of what drizzle is, is to refer to a “sprinkle”  as “drizzle.”   A sprinkle is a smattering of much larger drops that fall rapidly; never appear to practically float in the air.  In the parlance of the old teletype weather reports, they used to be described in “hourly” station reports, such as at Tucson, as “RW–“, that is, “very light rainshower”, and NEVER as “drizzle”!  But for some reason, not sure why, there has been a corruption of the word “drizzle” to more often indicate “sprinkles.”  These have even crept into the official reporting records, particularly at military stations such as Davis-Monthan for some unknown reason.

Since repetition is important for learning things, I have copied the two paragraphs above and have pasted them below:

Drizzle drops are defined by official weather folk who know what they are talking about as those drops between 200 and 500 microns in diameter.  A typical human hair is 100 microns in diameter.  So, they are darn small and have so slow a fallspeed that they appear to float in the air. If you ride a bike, you will know that no baseball cap will keep drizzle drops off your glasses.   The World Meteorological Organization’s description, is “fine, close together drops.” Furthermore, unlike yesterday when those drops were incredibly sparse, drizzle occurrences are often noted by lots of tiny drops in the air, 1os per liter of air if you want a number, which I doubt.  This often causes the visibility to be reduced, but it is also close to saturation in most drizzle, sometimes the visibility is reduced further also by fog.

A common misconception today by those ignorant of what drizzle is, is to refer to a “sprinkle”  as “drizzle.”   A sprinkle is a smattering of much larger drops that fall rapidly; never appear to practically float in the air.  In the parlance of the old teletype weather reports, they used to be described in “hourly” station reports, such as at Tucson, as “RW–“, that is, “very light rainshower”, and NEVER as “drizzle”!  But for some reason, not sure why, there has been a corruption of the word “drizzle” to more often indicate “sprinkles.”  These have even crept into the official reporting records, particularly at military stations such as Davis-Monthan for some unknown reason.

Finally, I would like to insult you by quoting from the Bill Nye the Science Guy program, one sponsored by the National Science Foundation, BTW, and his science ditty, The Water Cycle Jump:   “Your brain is on vacation, if you don’t know about precipitation.”

So there.

Finally, here are the clouds that produced the drizzle as it was happening.  You are looking at the west side of the Cat Mountains and you can see that those “Stratocumulus” clouds are quite low based, necessary for drizzle drops to reach the ground.   However, I have to say that they were still a surprisingly great height above the ground for a drizzle drop to have reached me.  That drop HAD to be much larger coming out of the base to have fallen, say 3,000 feet and reach me as drizzle sized.  An alternative explanation that would go with the very sparse nature of the drops was that the clouds reached below the freezing level and a few ice crystals formed, which then grew into raindrops (bigger than 500 microns in diameter).  TUS sounding doesn’t support this, but, BUT, the bank of clouds over Catalina was NOT over TUS at the time of the sounding release, so I think this is still a viable explanation.

The end.




Models wetting it up for Catalina and SE Arizona

This is one of the best days in my life!  The NOAA NCEP computer model has looked at the new data that came in overnight from around the world and now, in calculating the new maps from that data,  it thinks we are going to have quite the series of storms here in SE AZ!  Our spring grasses and wildflowers might yet get help in time to save the blooms!

Take a look at these images from last night’s NCEP model run reproduced by IPS Meteostar here (0ne of the best weather providers on the web in my opinion).  Below are highlights from IPS Meteostar model reproductions, namely those half dozen “future maps” having rain in them for around here.  BTW, a weather convention is that precip is colored green.

There are no less than six storms predicted to occur over the next two weeks!  It doesn’t get any better than this in you live in a desert!

Of course, if you’re a real weather forecaster, you know that it is likely that none of the below will be accurate.   But the excitement is in that it MIGHT happen just as the computers are predicting.  It’s something like a Fantasy Baseball team you have assembled prior to the season and in your players you see all their potential maximized.  In essence, it is just like this with last night’s model run, every rainstorm you see here, together as a unit of six, is like a fantasy team combining to win the pennant.  It probably won’t happen quite. But, the excitement is in the air, until those models break your heart by taking all the rain away in the next few runs, as they sometimes do.

Here are some maps from last night’s wonderful run with brief notes:

1) Valid this Thursday, most likely just a close call.  Note tiny green area just north of Tucson.




2) Below, valid Saturday, the 19th. Rain moves up northward from a band in northern Mexico and on this map, has already passed over Tucson.

3) Below, valid Sunday the 20th. Major southern California storm eases into southern Arizona!

4)  Below, valid Wednesday the 23rd, another rain!

5) Below, valid  Friday, the 25th of Feb, a real dump Mr. Model thinks.

6)  Finally, valid on February 28th, still more!  And man do we need it!

Distracted jet pilots or WHAT?

Now here’s something I have NOT seen before, which is pretty hard to have happen after decades of photographing the sky.   Here’s what I saw around 1:30 PM yesterday over Catalina.  I took three photos starting at 1:27 PM, 1:31 PM and 1:37 PM.  Here they are:

So, how to explain this odd “stitched” contrail?  Well, we can start with a few “facts” and hypotheses concerned with the aircraft and its crew.

1) Of course, with today’s modern instrumentation, pilots no longer have to actually fly commercial jets anymore.   They simply set their destination with their Tom-Tom GPSes;  flight levels and so forth, and then go to sleep until near landing time when they have to wake up again to be sure the automated process is still working.  Perhaps when I took these photos, the flight crew was napping and the plane was kind of zig-zagging around that bit, I’m sure  to the amusement of the passengers, who probably needed some excitement anyway to distract them from their cramped quarters.

2)  The pilots WERE flying the plane, but weren’t focusing on the task at hand, but were distracted while talking about stuff, maybe sports; perhaps recounting the great classic Superbowl game matching up two historic Rust Belt sports franchises, the Packers and the Steelers.

3) Since alcoholic beverages are available on flights, perhaps the pilots had some beer and while not necessarily really drunk, weren’t able to fly in a straight line.

Personally, I reject all of the above.  They appear to be “strawmen”, the result of superficial thinking strictly for entertainment purposes rather than having any intellectual depth.

Now for the “WHAT” part.

4) There are rarely seen regular undulations in the higher cirrus clouds in these photos, amazing ones really.  These reveal  waves pretty much perpendicular to the wind direction.  The flight track is along the wind (tail wind).   These waves in the atmosphere are like gigantic ocean swells, usually occurring where there is an noticeable increase in the wind with height.

Could these waves have produced this stitched pattern?   I am thinking “yes.”  That aircraft was likely close to the bottom of those cirrus (undulatus) clouds, and was SURELY experiencing those atmospheric waves, and likely exciting the passengers who probably needed some excitement to distract them from their cramped quarters-worth repeating.

We can’t tell here whether the contrail is rising and falling as would be happening in the cirrus lines and between them, respectively, or whether there is a perturbation to the horizontal winds associated with those waves.  A time lapse would be great here, and here’s one though it had some problems yesterday, from the University of Arizona’s Atmospheric Science Department.  A part of the contrail moves into the time lapse frames at 1:30 PM over Tucson, and from this angle, looking toward the Catalina Mountains to the N-NE, it does give an impression that the contrail was rising and falling.  Confidence is low here, though, in that description.

Here’s the last shot as this phenomenon and cirrus waves raced over the east horizon.  This last one makes it appear that the horizontal winds fluctuated more than the vertical winds under these waves producing a zig-zag in the horizontal.

With all the wonderful cirrus clouds around yesterday after a long absence, we had another one of those memorable Arizona sunsets, see last photo.

The End.

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.

Rain on model horizon. Yay, possibly, for spring wildflowers.

Thinking about wildflowers today, and prospects for a good bloom hereabouts are dimming.  But, rain is now showing up on the National Centers for Environmental Prediction (NCEP) GFS models on Thursday, Sunday, and again after the following Wednesday (can be seen here).  I am so excited!  Maybe this time these model depictions of rain in SE AZ won’t be numerical mirages as they often have been this winter 10-15 days in advance.  Model doesn’t seem to know about the “strange repulser” of SW storms, the La Nina phenomenon now in progress I guess.

Also, in the current spell of desiccation, there haven’t even been any cirriform clouds, those high ones that make the sunsets here so nice!

Things are looking pretty sad in the Catalina State Park and surround State free range lands as December rains-inspired grass starts to look a little stunted due to lack of rain over the past six weeks.  Don’t want to see hungry (?) cattle here and there eating cholla cactus.  See photo.  That is not a fake cow.  I filmed it gulping several cholla “fruit” down (film rated “PG” since its unimaginable that any living thing would devour something like a cholla bud, and your kids might start to cry if they see this).  ((Are there no nerve endings in cow’s tongue?)).  (((And if Ripley’s “Strangely Believe It” was still around, I would be submitting this cow photo so fast for some kind of prize.)))

Oops. what is a cholla “fruit”?  See next photo.  Cholla seem to like people.

Last, reminiscing over the fabulous 2010 wildflower show in Catalina State Park and environs, this 3rd photo:

Weathering extremes: what goes around comes around

Some brutal storms over the past year or so, such as the recent one that dropped 1-2 feet of snow from Tulsa to Chicago and beyond with sometimes hurricane force winds, have been labeled with all sorts of monikers, “Frankenstorm”, “snowmageddon”, etc.,  to emphasize how bad, and perhaps, how unique they were.  Some incautious observers have assigned such events to signs of global warming.  Moreover,  there have been seemingly oxymoronic,  perhaps ad hoc statements due to recent record cold spells that purport that it will be getting colder as it gets warmer (that is, we’ll have more severe cold winters as global warming progresses).

The impact of global warming to date is “relatively” slight, and no one can discern that a particular flood, typhoon, tornado, drought, that cloud over there, etc.,  was due to global warming.

We meteorologists know that “what goes around comes around”; that the “50 year”, the “100 year” floods will recur.  Namely, we know that extreme events will occur without the need to implicate global warming.

Furthermore, proxy climate records, such as tree rings that are rather good at delineating past droughty and wet periods–they are problematic in reconstructing temperature–but,  you can get quite a good handle on the precipitation regimes of the past few hundred years.  These, too, can tell us about the extremes of past climate over hundreds of years, and therefore, what to expect in the future sans global warming effects.

Perhaps one of the most important papers published in this proxy climate domain in this writer’s opinion was in 1994.  It was a study of rainfall epochs deduced from tree rings in central California by Haston and Michaelsen, published in J. Climate.  It is fortunate that this study was published before the global warming “media blitz” in which otherwise reasonable people/media assign all kinds of anomalous weather events to signs of global warming.

What was the main conclusion of that J. Climate paper regarding rainfall regimes over the past 600 years in California???

It was astonishing.

The authors concluded that the California water retention and flood control infrastructure had been built based on an unusually low degree of climate variability during the instrumental record, largely confined to the period after 1900.  The longer tree ring record, however,  CLEARLY indicated that much LARGER fluctuations in the rainfall regimes of California had occurred prior to the instrumental record.   These findings led the authors to suggest that California was not likely to be well prepared for the floods and droughts of the future since it can be assumed that larger variability in rainfall found in the past will occur in the future.

The record rains of the 1997-98 El Nino and 2004-2005 rainfall seasons accompanied by an almost unheard of water flows into the basins of Death Valley in 2005,and  the “unprecedented” drought of the 2001-2002 rainfall season in which some coastal southern California sites received less than 2 inches (!) were largely foretold by those 1994 findings.   Moreover, due to the “teleconnection” aspect, the larger climate variance found in central California prior to record keeping can be expected to have repercussions in the adjacent states.

What “goes around”, has already begun to come around.

But in today’s world, these anomalous weatther events will not be seen as just,  “what goes around comes around”, but rather will be labeled en toto as evidence of the pernicious effects of global warming.

That’s just plain wrong, and most meteorologists understand this.

The extreme events of late, if you are onboard the GW bandwagon, could reasonably have been said to have been “tweaked” by GW at best.  Perhaps without GW, that snowstorm in Chicago would have dropped “only” 18.3 inches instead of 20  associated with overall slightly higher temperatures and the attendant enhanced moisture content.

The late Prof. Joanne Simpson, former president of the American Meteorological Society, warned, in the early days of global warming claims in 1989,  claims that many scientists were dubious of at that time, about the dangers of exaggeration.  She recounted her experiences with the exaggerated claims promulgated in the cloud seeding domain in which she worked.   In her talk at the Conference on Statistics and Probabilty in the Atmosphere, Monterrey, 1989, and as President-elect of the American Meteorological Society, Dr. Simpson warned:

“Lacking that lesson, our community has once again stumbled into the weather modification paradox concerning global warming-where again we may be damaging our credibility again for the same basic reason.

“What is the weather modification paradox?  It is the tendency to exaggerate man-made alterations to the atmosphere owing to the great difficulty in distinguishing definitively between natural variability in the system and anthropogenic effects-whether the perceived man-made change is small-scale rain produced produced by intentional cloud seeding or whether in it long-range global warming as a by-product of industry and agriculture.”

and, near the end of her talk that day, she re-emphasized this point:

“While it is not entirely clear what the decision makers of the world can and should do, I hope at least that we meteorologists have learned some hard lessons.  I hope that we have learned enough from the harm that we and our colleagues have caused over the years by exaggerated claims and exaggerated scare stories.  I hope that we will be more cautious in how we express ourselves, especially to the media–that is a difficult challenge to say the least.”

Joanne Simpson was not too skeptical about a global warming future, but she was concerned about how we spoke to the public about it.


PS:  Prof. Simpson’s full address, which she provided to me soon after it was delivered, can be found here:  all of Joanne Simpson’s banquet talk wx mod and GW_1989.


BTW, and unexpectedly, global temperatures have stabilized over the past 10 years or so in spite of continuing increases in CO2, as many of you knowWhat happened to GW_Sci_Oct 2, 2009.  One explanation posited for this is a drying of the stratosphere, something that would allow more of the earth’s heat to escape into space–Solomon et al. 2010,  Science). Another explanation for at least part of this “stabilization” arises from an climate model using recent ocean current data.  The output from this model predicted that cooling of the northern hemisphere continents was due to a recent slowing of Atlantic Ocean currents, and furthermore, that this slowing and continental cool spell was likely to last 10-20 more years (Keenleyside et al. 2008 in the journal Nature, summarized by Richard Kerr in Science).  Finally, we have an aerosol “wild card” out there. Aerosols are thought to have the net effect of lowering global temperatures, but the models used by the IPCC4 were only able to crudely parameterize those effects.  One down-sized climate model (20-25 km grid spacing instead of 200-250 km), in preliminary runs has suggested a larger role for aerosols in cooling the planet, a kind of inadvertent “geoengineering.” (These latter results have not been published that I know of, and so this comment can only be considered little more than gossip at this time, but it was from a good “insider” source.)

However, imagine how pathetic such a smoggier world would be, with smog everywhere, views of the Grand Canyon mucked up, even thin, smog-laden stratocu looking dark and ugly on the bottom as as more light was reflected back into space from their tops due to smaller drops, etc.   Getting upset here even thinking about how awful that smoggier, less warm, world would be!  Don’t “geoengineer” in this way!!!