Not much going on lately, so will dip into the archives from two days ago. One cloud in particular was so spectacular in its defiance of gravity, rocketing upward the morning of the 4th. So here are shots from that day…
6:46 AM, Aug. 4: The day began with a pretty normal looking patch of Altocumulus perlucidus (honey-comb pattern). No virga, so its likely not too cold. The sounding suggests it was up at 16,000 feet ASL, or 13 kft above Catalina at about 0°C (32 F).
10:05 AM. Thar she blows! Just a spectacular jut from over the Mogollon Rim area, and a telling sign of what was immediately ahead for us.
10:53 AM. Was doing yard work, under some trees, and then came out to see this amazing sight (Cumulus congestus erectus). Ran for camera, you have just seconds to a minute or two before it begins to fall apart due to entrainment of dry air that makes a cloud look ragged and frayed. Will it form ice? Is it cold enough up top? Should show up in a couple of minutes if it is going to.
11:00 AM. Ice formation well underway as you can see by the frizzy, fibrous texture above the halfway mark up this cloud. At the time it seemed like it might be a big day for TSTMs with this kind of vertical rocket cloud shot so early. But, no. I would term this cloud, a Cumulonimbus calvus or capillatus, even though there is no visible rainshaft yet.
11:00 AM. Going zooming…you can see that virtually this whole top is glaciated, and that fingerling, top left, shows some fallout of ice, likely aggregates of ice crystals. When concentrations are high, as would be the case in this glaciated turret, the crystals often lock together to form snowflakes. In cloud microstructure and modeling terminology, the stuff falling out would be termed , “precipitation ice”, and most of that in the fingerling, “cloud ice.” I hope you’re happy now.
11:05 AM. An icy being seems to be leaping out of the new Cumulus congestus clouds that sprang forth so rapidly. That icy “being” is all that’s left of the original turret.
11:09 AM. Kind of in the area of “beings” now. Those new Cumulus cloud sprouted up rapidly to fill the void left by our first cloud. But here it appear to take on the shape of a being waving, “Hey, look at my icy left hand!”
11:52 AM. Thought this frizziness, texture of the ice made me think they might be “warm crystals”, that is ones that form at temperatures higher than -10°C, which would be needles and sheaths…. I sure wish I had a Learjet, get up there in a hurry, find out for sure…. The afternoon sounding supports that speculation with tops likely limited to those higher temperatures, but not the morning one
12:49 PM. One Cumulonimbus calvus stage here, was potent enough to produce a bit of thunder, maybe the last we’ll hear for many days.
1:00 PM. Looking to the west, you could see the drier air moving in as evidenced by the lack of any buildups for as far as you could see, and also in the pitiful clouds over the Tortolita Mountains. It was a hard time, knowing the end was at hand. And there it is, below: