This is NOT about Cream, the Eric Clapton-led group who did the song, Strange Brew which I allude to in the title, though I did like that song at the time. (The link is hilarious. What were people thinking, dressing like that? And that hair on the expressionless Clapton!)
Yesterday was an interesting day with some gorgeous clouds, some light rainshowers and a tornado–well, not quite–but almost. A long funnel cloud appeared and re-appeared three times in succession over there by the Tortolita Mountains. Since this is the internet and you might not believe me, here is the proof in these photos taken in mid-morning:
Less sensational, erudite part of today’s yesterday’s rehash
Yesterday we had clouds developing rain by the “warm rain process”; light rain showers that fell from clouds with no ice, except maybe for one maybe that did appear to get a little ice in its top.
The formation of “warm rain”, something that occurs, say, in Hawaii all the time, and along the coasts of the continents, RARELY occurs in Arizona. Cloud bases have to be particularly warm (“check”, 15-17 C, around 60 F) in the morning hours yesterday), the air relatively “clean”, that is, free of much air pollution (“check”, due to rain lately), and perhaps even more importantly, updrafts that at the bottom of the cloud that relatively sluggish (check, weak updrafts only activate the biggest, best cloud condensation nuclei, insuring few and larger drops. I think that was a real contributor yesterday morning). Rarely are our high Cumulus cloud bases warmer than 10 C (49 F).
The last two factors, clean air, weak updrafts at cloud base, mean that the droplet concentrations in the clouds will be low. Low droplet concentrations mean that each itty bitty cloud droplet will carry more water, be larger in size than a cloud with high droplet concentrations in which the condensed water spread on many, many more drops that HAVE to be smaller.
“So whut?”, you say.
Well, when cloud droplets reach sizes between 30-40 microns in diameter, HUGE for drops formed by condensation alone, something rare here, they can bump into each other without bouncing off one another like ping pong balls, but can collide and stay together as one much larger drop (remember Hocking 1959? The reprise, Hocking and Jonas 1970?). Remember, too, that cloud droplets smaller than 30 or so microns have hardly any fall speeds and so those drops just hang around up there not doing anything but trying not to evaporate (“die”).
That larger drop that results from coalescence, then falls much faster, bumps into more of those larger in much more violent collisions, cloud drops and soon is a billion times bigger than a cloud drop. Drizzle, fine drops of thick, misty rain that almost floats in the air, but drifts toward the ground at 1-2 meters per second , about like a walking speed, from Stratus or Stratocumulus clouds is always formed by this process. This in turn tells you something about the drops in the clouds overhead. Tell your friends.
Remember that rain CANNOT form through condensation of water on nuclei alone! Your local weather presenter might assert this unless he/she is quite good and really knows stuff. There HAS to be ice, OR, collisions with coalescence. Sometimes ice AND collisions with coalescence are happening in the same cloud, ones with warm bases but also having high tops, ones above the -5 C, 23 F) level in the atmosphere.
Yesterday, nearly all of our clouds that sprinkled in the morning (a trace here) a bit did not reach above the ice-forming level of -5 C, and certainly, in the opinion-assessment of this eyeball, did not reach the -10 C (14 F) level.
Here is the one top that appeared to have ice in it. Can you find it without an arrow? That would be great, quite an advance for you, since it is pretty hard to see. First the pretty sky with two main clouds, then a close up:
Today?
AZ mod here has a surprising chance of showers late in the afternoon here. Did not expect that. Fingers crossed for ONE MORE DAY!
The End.
