Category Archives: Cirrocumulus clouds

What’s Up with This?

Got pretty mad yesterday when I saw this overhead in some Altocumulus perlucidus clouds.  You’ll have to hold your monitor or Ipad, or cell phone, or whatever, over your head to see it EXACTLY the way I saw this because it WAS overhead;  straight up.  (Actually, doing 3 sets of 12 might be good for you.)  Also, click on images to get the full view.

As you can see, the white strip below in these clouds is a contrail caused by an aircraft, but a special one that occurs in “supercooled” clouds.   Supercooled clouds are clouds that are composed of drops, yep, they’re still liquid, even though the temperature is FAR below freezing.  Here, the clouds were likely colder than -20 C (-4 F) and yet there is no ice forming in them!  (You don’t see trails of snow coming out, do you?  No.)  Run of the mill contrails occur at cirrus levels at temperatures below about -35 C  (-31 F).

Note that except for being much whiter than the surrounding cloud, the elements are exactly the same size and texture as those around it.  That is going to change, because this white strip is composed of “horrendous” concentrations (probably thousands per liter) of ice!   You can only know this by what happens later.

In the next shot below, is an example of what happens later, trails of tiny snow crystals fall out leaving a hole in the droplet cloud, so called, “hole punch” clouds, a form of inadvertent cloud seeding by aircraft.  Note the delicate strands of ice crystals falling out of this cloud from the hole, so pretty because they are so delicate looking.  Note, too, I am one of the “trailing authors” of the journal article above, like one of those itty bitty ice crystals in the second photo which are almost evaporated at the bottom of those fine strands.

So why be upset?

Rather than looking forward to good things in the coming year, this happenstance yesterday reminded me of all the trouble we had in the early 1980s trying to get our paper published on this phenomenon; namely, that an aircraft could produce tremendous amounts of ice when flying through supercooled clouds, inadvertently seeding them.

In the SECOND rejection of our manuscript (with Pete Hobbs), the Editors words still burn; “(the reviewers) are still unconvinced by these controversial claims.”

We had to do a LOT of extra work on this to convince those reviewers.  The third version was more convincing, I guess, for intransigent reviewers, and got published.  In fact, one of the great scientists of our time as far as clouds and ice crystals go, John Hallett (yes, the same one as in the “Hallett-Mossop” ice splintering process),  speaking at the Peter Hobbs Symposium Day in 2008 called this episode, “an embarrassment for the airborne research community.”  “Hey”, he wasn’t referring to our paper!

He was referring to the fact that such a phenemenon had been overlooked and not accounted for in research studies of clouds by aircraft.  Actually ground observers had been reporting this kind of thing (ice canals and hole punch clouds) since, if you can believe it, the 1930s!

BTW, this hole is not the one from the first shot; I got distracted and forgot to follow it until it was disappearing over the horizon.

BTW#2,, this shows what happens when you introduce ice into a supercooled cloud; “stuff” falls out.  Proves cloud seeding works, though for sure in limited venues like these (non-precipitating, supercooled clouds).

BTW#3:  The second photo is a nice example of the difference between supercooled clouds composed of tiny drops (probably less than 20 microns in diameter), and cirrus-ee ice clouds, composed of much larger crystals (here probably 100 or 300 or so microns in maximum size) that tend to settle with time. (Hence, those strands in most cirrus clouds.

BTW#4:  Today’s title is cribbed off the world’s most viewed climate website, “What’s Up With That?”  Mr. Watts, host of the site, has made significant contributions to our climate network by pointing out flaws, but has no “credentials” beyond having been a TEEVEE meteorologist.  He is excoriated on this point alone by “credentialists”, as I myself was when I first began to reanalyze other folks’ cloud seeding experiments such as this one.

BTW#5, a movie about credentialism is now out, called,  “The King’s Speech.”  I highly recommend it.   In this documentary, which I just saw yesterday, it will be seen that the credentialists in the King’s Court were royally put out by the help the King got by his uncredentialed therapist.