Category Archives: Guinness record

Morning smog bank invades Catalina, smokes up clouds real good

I wonder if you noticed the blackish smog layer to the south and southwest of Catalina yesterday?  Usually it stays down that way, flowing peacefully toward the northwest from Tucson across Marana and Avra Valley, an area where a close meteorologist friend and his wife just bought a house even though they knew this happens in winter and not one in Catalina where we normally escape this characteristic Tucson smog plume. They must like winter smog overhead, but then as the sun heats the ground, it comes down to you. Go figure.

Here is yesterday’s Tucson smog plume exiting Tucson:

8:47 AM.  Smog plume exiting Tucson, moving left to right over Twin Peaks area.
8:47 AM. Smog plume exiting Tucson, moving left to right over Twin Peaks area.  This was one of the densest, most awful ones I’ve seen from Catalina.

But then, in the later morning hours, a southerly wind brought that smog bank to our normally clear air oasis of Catalina, infecting the shallow Cu fractus clouds that formed as the sun heated the ground.  This was a real disappointment since probably most of us were expecting the kind of pristine view of the Catalinas yesterday morning.

10:09 AM.  Smoke-filled Cumulus fractus clouds form along the Catalinas as the air begins to warm.
10:09 AM. Smoke-filled Cumulus fractus clouds.  The smog looks white here instead of dark because of “forward scattering”; the white light of the sun is being scattered in the viewer’s direction by the smoke particles.  (In the first photo, there was no forward scattering and so you can see the actual dark hydrocarbony smoke particles for what they are, dark and sooty.

Fortunately the smog was dispersed as the day wore on.  As the layer in which it is contained gets deeper, and without more smog being added to it, the amount of smog, say, per cubic mile diminishes and pretty soon it gets so thin you can’t detect it with your eyes.  Still,  exactly the same amount might be in the column of air between you and the higher cloud bottoms.   Here’s what it looked like in the later afternoon:

4:29 PM.   That's better!  Cumulus humilis dot skies.
4:29 PM. That’s better! Cumulus humilis dot skies.

BTW, while its easy to see that the Cumulus fractus clouds in the second photo are very low, in the 3rd photo above  it’s much harder to detect how high these small Cumulus are. The TUS sounding indicated that they topped out at 9,000 feet, or only about the same height as Ms. Mt. Lemmon! Top temperatures in these smoke-filled clouds were no colder than about -8 C (about 20 F), too warm for ice to form in them, especially when the cloud droplets are reduced in size by smog.   The larger the cloud droplets, the higher the temperature at which ice begins to form in them, and so smog generally reduces the chance of rain in shallower clouds.

This is why oceanic clouds in pristine regions lacking smog, even shallow ones,  rain or drizzle so easily.  The cloud droplets are much larger in those clouds right from the get go than those in smoggy regions.   So oceanic clouds can rain either because those larger cloud drops reach sizes where they can collide and stick together, forming larger drops that can fall out (“warm rain process”) or form ice at the highest temperatures known for ice formation, -4  to -5 C (23-25 F).  Usually both processes are work in those ocean clouds that rain so efficiently.  They’re pretty great,  really, such little clouds that rain.

Vacation in Hawaii if you’d like to see some up close (though not downwind of the Kilauea volcano plume and in the lee of the Big Island of Hawaii since that volcanic plume can smoke up the clouds real bad there and they stop being so darn efficient as rain producers.  Recall that the biggest drop in the world was measured in clouds in Hawaii (1 cm in diameter, Beard, private communication,  received AFTER Peter Hobbs and me got the Guinness record for the biggest drop ever measured, 8.6 mm in diameter–got a lotta publicity around the world, too, calls came from everywhere!).

You see, Beard didn’t publish anything about HIS BIG DROP; we published ours in a refereed journal. “Neeny, neeny, neeny”, I think is what you conclude here.  Immaturity:  sometimes I think its not valued enough in life.

That’s what its like in academia; you publish or die!  Die that slow death as an “Assistant Associate” professor of something, never reaching the exalted “Professor” status.

The “combo” ice seen yesterday morning

We had two forms of ice yesterday morning that you may have noticed, say, on your car if it was parked outside overnight.  There were originally rain drops left from the storm that froze in place during the cold night (was 30 F here yesterday morning), and then the deposited ice from water vapor on top of the drops.

The deposition process, as we call it, leads to hoar frost ice crystals growing in time as the molecules of water vapor add to it during the night.  This combo ice led to an unusual site on the car before the sun did away with it.  Here are a couple of shots of this unusual sight:

9:57 AM.  "Strange brew."
9:57 AM. “Strange brew.”


9:58 AM.
9:58 AM.

The weather ahead

After the “sunny malaise” for 5-6 days, with Arizonans statewide out doing things, its back to the Bowl, the trough bowl.  The period we’re in now might be called, “a sucker ridge”, a high pressure ridge that is.  You might well think, “Well, that’s it for winter in Arizona!” after a few days of the “sunny malaise”, but you’d be WRONG.  I can’t emphasize the word, “wrong” enough.  The Bowl comes back with a vengeance, too, when it reforms here in the Southwest;  there will be one storm and cold blast after another.  If you’re a snowbird, you might start to cry, and wonder why you didn’t go to Costa Rica for the winter.

Well, I am looking forward to storms and seeing more scenes of white mountains deep in snow, and green vegetation shooting skyward.  That’s the promise of the “Bowl” ahead, where storms collect,  in the weeks ahead right into March.

Taking a few days off now, likely without pay, to replenish mind, get out and do things like the rest of Arizonans will.   Will give you time to ruminate on all that’s been said here over the past year or so, correct and incorrect, mature and immature…

The End.

Yesterday: a rare drizzle occurrence in the morning and later, gorgeous Cumulus-filled skies

First of all, Happy New Year to both readers! Thanks for hanging in there.

The weather ahead…

before a long diatribe about drizzle, followed by some pretty pictures with explanations:

Some picaresque Cirrus later today. Looks like next chance for rain is around the 10th-11th of Jan.

A rare drizzle occurrence

Cloud maven juniors were probably excited beyond description when they went out yesterday morning between 9 and 11 AM and intercepted a rare occurrences of brief drizzle here in Arizona falling from that low-hanging Stratocumulus overcast.  This happened after several very light RAIN (not drizzle) showers dropped another 0.02 inches, raising our storm total here in Catalina to a respectable 0.30 inches.

Drizzle is composed of drops barely large enough to cause a  disturbance in a puddle of water1, as though a large particle of dust had landed in it.  Drizzle drops nearly float in the air (should not be falling at more than about 3-4 feet a second), and in many cases of very light drizzle, the drops can float around like “desert broom” seeds. Visibility is usually lowered, things look fuzzy in the distance. Drizzle precip is so light it can’t produce even 0.01 inches except over periods of an hour or more.  Drizzle drops are also more uniform in size than the drops in rain, and are usually very close together.

While drizzle is common along the west coasts of continents in coastal Stratus and Stratocumulus clouds, its much rarer at inland locations such as here in Arizona, thus, the excitement over seeing it yesterday.

The reason why its rare in AZ?

Shallow clouds that drizzle must be what we would term, “clean” clouds; they don’t contain many cloud condensation nuclei and so droplet concentrations are low, maybe 50-200 per cubic centimeter (might not sound low, but for a cloud, it is). Clean evironments are found over the oceans and for awhile, in air coming inland along the west coasts of continents in onshore flow before it gets contaminated with natural and anthropogenic aerosols (smog).   Man, we are getting into a real learning module here!  Wonder if any readers are left?  Probably talkin’ to myself now.  Oh, well, plodding on. Nice photos below…far below.

Drizzle occurrences tell you a lot about the clouds overhead.  Not only are they low-based as is obvious (they have to be or the drizzle can’t reach the ground), but they are relatively shallow clouds no matter how dark they look.  Furthermore, and more subtle, they have larger cloud droplets (ones to small to fall out as precip) in them that must be larger than about 30 microns in diameter (smaller than half a typical human hair diameter).  When this larger size is reached in clouds, and those drops are pretty numerous, say 1000 per liter, they begin sticking together when they collide in the normal turbulence in clouds.  Those collisions with coalescence result in drops that fall much faster, bump into more drops, growing larger and larger until they fall out the bottom.

In a shallow cloud, those drops can’t get larger than drizzle drops, and that’s one of the ways you KNOW that they are shallow no matter how friggin’ dark they look.

Aside about rain not due to the ice process:
The largest drop ever measured, 1 cm in diameter, was observed in a Hawaiian Cumulus cloud that did not reach up to the freezing level!  Unfortunately, the authors of this finding did not publish their results and so did not get a Guinness record like me and Pete Hobbs did when we reported a smaller 0.86 centimeter diameter drop in Geo. Res. Lett., 2004–found them in Brazil, and again in the Marshall Islands–hit the pilot’s window like little water balloons.  Instead of being in a book with other famous people, like ones who can eat 47 hot dogs in 12 minutes, those researchers who encountered that larger drop in Hawaii sat on their finding! Unbelievable.

Strangely believe it, from lab experiments, drops bigger than 0.5 cm are not supposed to exist, but rather break up around 0.5 centimeters in diameter.  (hahahahaha, lab people). End of aside.

1Officially, 200-500 microns in diameter, equivalent to a couple or three of human hairs, maybe ONE or two horse’s tail hairs, to add a western flavor to the description.)

Yesterday’s gorgeous skies!:

Took more than 100 photos yesterday.  Was out of control, euphoric, thinking how great this earth is, maybe leaning toward thoughts of higher being and creativity therein, thus explaining the “creative” punctuation above.  Here are a few shots of those magnificent clouds and our magnificent, snow-covered Catalina Mountains.  First, those drizzle-producing clouds:

10:12 AM. Last of the drizzling Stratocumulus overcast. Patchy area of drizzle to west on the Tortolita Mountains here. The Stratocu gradually broke up after this time.


11:54 AM. Stratocumulus clouds still in charge, but lift here for a peak at the new snow on the Catalinas.
12:13 PM. First snow showers appear to the north-northwest as the stratocu deck begins evolving into Cumulus congestus and small Cumulonimbus clouds with large breaks.
12:35 PM. Snow showers from relatively shallow Cumulus race along the Catalina Mountains. These kinds of snow showers occurred right up until late afternoon.
12:37 PM. Snow and light rainshowers from shallow Cumulonimbus clouds also begin moving into Oro Valley before striking the Catalinas. Look at how similar these smaller clouds with their rain/snow shafts appear to our summer giants.
12:59 PM. Shower over the Oro Valley moves onto the Catalinas. Arrow points to a filament/strand coming out that is almost certainly composed of graupel (soft hail), something that was common yesterday from these clouds.
2:38 PM. HOWEVER, graupel often falls out of Cumulus congestus clouds on their way to being a Cumulonimbus without any sign of precip overhead, as here. This is because you are getting the result of the very first ice to form and fallout, usually those first ice particles are pretty rare in many of the shallow clouds as we had yesterday, and, because the updrafts are weak, they fall out as isolated little snowballs, too few to produce evidence of a shaft. But hang on, a shaft often, in the deeper clouds, imminent.
Also at 2:38 PM, looking northwest. A view of smaller Cumulus with the deep blue of the winter sky we love.
3:07 PM. “Congestus on the Catalinas.” You might ask, “where’s the ice?”, since yesterday all clouds reaching this size produced ice/snow/rain. Well, its on the other side (due to wind shear that carried the ice off toward the east. I think that’s the real reason why “the bear went over the mountain”, as we used to sing.

3:11 PM. Example of the medium Cumulus clouds (mediocris) that developed ice in them yesterday because it was so cold aloft, tops here colder than -12 C. (estimated).  Arrows point to ice, necessary for measurable precip here.
3:50 PM. Another modest Cumulus with plenty of ice (probably 10s per liter if you were guessing). Lowest top temperature likely lower than -15 C.

4:08 PM. I have no idea. This patch of ice cloud is left over, a “ghost” really, of a medium Cumulus cloud whose droplets evaporated. But what would it be called now? Altostratus translucidus cumulomediocristransmutatus? Cirrus spissatus cumulomediocristransmutatus? Silly, but I know of no name for such a patch of ice/virga
4:49 PM. You knew that on this cold day you would be treated to some of our finest scenes in winter, golden scenes of cloud-capped, snowy mountains, and later, those rosy under lit remaining small Cumulus and patches of Stratocumulus. What a fine day it was!

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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











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


The End (at last)