High cold ones, and lots of patterns in a complex sky

In particular, those Altocumulus clouds, “cold” Cirrocumulus (ones that transform to ice immediately),  and those “Altocumulocirrus” clouds combining  with  scenes of “regular” cirriform clouds.  Lots of interesting sights to have seen yesterday.  All these the result of marginal moisture aloft and strong winds, up around 100 mph at the highest Cirrus levels.

Let us begin as cloud maven folk by examining the late afternoon sounding launched from our Wildcat balloon launching machine at the University of Arizona, courtesy of IPS Meteostar:

The temperature and humidity profile obtained from a weather balloon launched at about 3:30 PM yesterday afternoon from the U of AZCats.
The temperature and humidity profile obtained from a weather balloon launched at about 3:30 PM yesterday afternoon from the U of AZCats with some suggested cloud levels.  The Altcoumulus level is in doubt. the others are pretty straight forward.  Notice how high those little Cu were yesterday afternoon, about 16,000 feet above sea level, or about  13,000 feet above Catalina, with bases at a cold -13°C or so.  No ice came out of those, though.  Likely droplets too small, or short-lived.
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6:45 PM. A very narrow line of Altocumulus castellanus and floccus virgae approaches Catalina.
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6:46 PM. Let us exercise our curiosity and examine this element in more detail below.
6:47 PM. Altocumulus floccus virgae. Another example of how the top of a storm, as here, can be composed of droplet cloud while the ice that forms in it falls out below. Here, the extreme dryness underneath the Altocu prevents long trails. The ice crystals wither so that they have almost no fallspeed soon after they have fallen out, leaving a flat bottom of tiny ice crystals.
6:47 PM. Altocumulus floccus virgae. Another example of how the top of a storm, as here, can be composed of droplet cloud while the ice that forms in it falls out below. Here, the extreme dryness underneath the Altocu prevents long trails. The ice crystals wither so that they have almost no fallspeed soon after they have fallen out, leaving a flat bottom of tiny ice crystals.  When you see tiny cloudlets like this spewing ice, you KNOW that the temperature has to be extremely low, and colder than -30° C (-22°C) would be a good starting guess.  Actually, guessing “-31.3° ” would be more impressive to your friends or neighbors….   It was a pretty scene, that’s for sure.
5:37 PM. Pretty iridescence occasionally erupted in newly formed Cirrocumulus, newly, as within seconds or in the last minute when the cloud droplets are extremely tiny, less than 10 microns in diameter. You don't see iridescence in clouds with droplets much larger than that.
5:37 PM. Pretty iridescence occasionally erupted in newly formed Cirrocumulus, newly, as within seconds or in the last minute when the cloud droplets are extremely tiny, less than 10 microns in diameter. You don’t see iridescence in clouds with droplets much larger than that.  And, it has to be pretty much overhead to get the best views.  Hope you saw those yesterday.
5:41 PM.
5:41 PM.
5:43 PM. ??????? These are little cloudlets of ice up at Cirrus levels, but it looks exaclty like a field of normal Altocumulus to the ordinary eye. "Altocumulocirrus"?
5:43 PM. ??????? These are little cloudlets of ice up at Cirrus levels, but it looks exaclty like a field of normal Altocumulus to the ordinary eye. “Altocumulocirrus”?  Without doubt this “ice” composition would be contested by other observers.  However, cloud-maven person’s interpretation should be used.  Now it is likely that the ice in these clouds first formed on what we deem as “cloud condensation nuclei”, and it might be likely that water saturation was reached.  But, if there was an instant of liquid, is certainly transitioned to ice in seconds since the temperatures at Cirrus levels were well below -40° C.   I don’t believe this was at the same level as the Altocu shown in the beginning of this writeup, yet it wasn’t as high as the highest Cirrus yesterday (up around the -50° C level).
6:07 PM. An example of how complicated the cloud scene was yesterday. The whitish clouds in rolls were icy cirriform clouds, and the delicated clouds were HIGHER Cirrocumulus and Cirrus. Cirrocumulus yesterday was indeed where most cloud schematics put it, at Cirrus levels, though probably half the time its in the mid-levels were Altocumulus clouds reside. So, with Altocumulus-like clouds at Cirrus levels and Cirrocu on top of Cirrus, it was really a crazy cloud day yesterday.
6:07 PM. An example of how complicated the cloud scene was yesterday. The whitish clouds in rolls were icy cirriform clouds, and the delicated clouds were HIGHER Cirrocumulus and Cirrus. Cirrocumulus yesterday was indeed where most cloud schematics put it, at Cirrus levels, though probably half the time its in the mid-levels were Altocumulus clouds reside. So, with Altocumulus-like clouds at Cirrus levels and Cirrocu on top of Cirrus, it was really a crazy cloud day yesterday.  At the very top of this photo were Altocu that were immediately ice clouds that might have comprised a separate third level of clouds.  Need a Lear jet to get there fast to resolve these many guesses.
5:07 PM. Jumping around in time.... These were some of the best scenes yesterday IMO, those oh-so-delicate patterns in those cold Cirrocumulus clouds, ones that transitioned to Cirrus clouds downwind.
5:07 PM. Jumping around in time here…. These were some of the best scenes yesterday IMO, those oh-so-delicate patterns in those cold Cirrocumulus clouds, ones that transitioned to Cirrus clouds downwind.
5:08 PM.
5:08 PM. Same patch Cirrocu.  Note Cirrus forming in the lower portion of this photo, once Cirrocu.  BTW, all power lines should be placed under ground.
2:29 PM. Amid some real Cumulus fractus was some Cirrus "cumulus mimicry" I've termed "Cumulo-cirrus". Can you spot the fakes at Cirrus levels? Its pretty hard.
2:29 PM. Amid some real Cumulus fractus was some Cirrus “cumulus mimicry” I’ve termed “Cumulo-cirrus”. Can you spot the fakes at Cirrus levels? Its pretty hard.
2:29 PM. OK, I give up. Here's a zoomed shot of Cumulus fractus mimicry by clouds at Cirrus levels. Might have been some droplets, too, before converting to ice.
2:29 PM. OK, I give up. Here’s a zoomed shot of Cumulus fractus mimicry by clouds at Cirrus levels. Might have been some droplets, too, before converting to ice.  These kinds of clouds suggest significant turbulence at this level, as would be in a regular Cumulus fractus cloud.

The weather way ahead

Still looking for that chance of rain before July….  haha

Troughy conditions will actually recur aloft over us over the next few weeks it seems, which means slight chances of rain, but periodic cold fronts passing by, mostly dry ones.  Best chance for rain still seems to be around the 20th, plus or minus a day or two, even though mod outputs have backed off that scene.  But, we have our spaghetti that tells us the models will likely bring back that threat around the 20th, even if some individual runs show nothing at all or only close calls.  We shall see if this interpretation has any credibility at all, won’t we?

Of note, Cal having big April in rain and snow after the gigantic January and February accumulations!  Looks like they’ll continue to get slugged by unusually strong storms, off and on, for another couple of weeks.  Water year totals are going to be truly gigantic.

The End

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.

2 comments

  1. Hi Art; Guess what? We have a sunny day here today! I’ve finally had a chance to see clouds other than the usual Ns, Sc, Cu+ types that have been dogging this area for so long! But- can’t have too much of a good thing: Tomorrow it’s back to rain… Hope you get some too before July. Happy Easter!

  2. Wow, a sunny day there in Vancouver! Amazing. Wasn’t sure they had them that far north.

    Thanks for the Easter wish, Roland. Same to you!

    a

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