Thunderstorms in the distance crept toward the Catalinas late in the day, and after sunset, an approaching, but thinning anvil of a dead Cumulonimbus cloud (no updrafts remaining to feed the anvil) produced this beauty. With the death of this prospect, any hope of rain moving in here later in the evening went six feet under as well.
The anvil below looks fairly close, but if you go to the U of A time lapse, this anvil comes onto the field of view at about 7:40 PM, and you can get an idea of how much farther the anvil below had to go to be above the Cat Mountains.
For the second day in a row there were virtually no Cumulus clouds over our Catalina mountains, a real disappointment. But, undaunted, Mr. Cloud Maven person will anticipate Cumulus clouds over the Catalinas once again today, following in the same wrong footsteps of the past two days, and will again foretell that these will be ones that will rise high enough to “glaciate”, that is, have their tops convert from liquid droplets to ice crystals.
The result of this “glaciation” process is something coming out the bottom of the cloud, a dense shaft of precip, as a Cumulus cloud transforms itself into a Cumulonimbus one.
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Science Story: This is always an exciting sight and a process that Mr. Cloud Maven person (MCMP) spent some 25 odd years studying with a highly instrumented aircraft at the University of Washington but couldn’t quite figure out how it happened. In fact, MCMP (with his lab chief co-author) were criticized royally (i.e., Blyth and Latham 1998) for what they did report over the years (“royally”; they were two British guys, but working in the US). We “Reply” to their comments in quite substantial fashion in the same issue (Reply to Blyth and Latham)!
BTW, real scientists, like Alan Blyth, are still working on this problem; how clouds glaciate. Its pretty amazing when you think of it. These days the Japanese (asteroid dust Science-2011) can send a spacescraft to an asteroid named, Itokawa, land on it, pick up some dust grains, and bring them back, a process taking more than 10 years, but we really don’t know completely how ice forms in a cloud!
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Back to the local scene:
once again we have our high surface dewpoints, in the upper 50s (58 F here in Catalina) and even 62 F now at Douglas. So the bottom of our atmosphere is OK for Cumulus. And once again, we have an overcast of mid-level Altocumulus clouds. A problem yesterday was the extreme dryness above that surface moist layer, and below the Altocumulus one, a shallow moist layer that was completely obliterated after the sun came up and the dry one and razor-thin moist one mixed together. Its not so dry today above the low humid layer today, and so Cumulonimbus clouds should be able to develop in the area.
Besides the models told me so. Have been a little sloppy and a little, well, arrogant, about reading the early morning sky absent more information.
Here’s today’s TUS sounding, from the Wyoming Cowboys, so you can see for yourself.
The End, unless I find out I am going to be wrong again when more data comes in a couple of hours.
