Cloud quiz

While waiting for the rain, here are some of yesterday’s clouds.  What were they?

Answers printed upside down at the bottom except that WordPress wouldn’t let me do that.  It would be great if you turned your monitor upside down before you looked at the answers.  One is a trick “question” because I took a picture of a cloud behind what appears to be an inanimate plant, focusing on the dead plant and so the cloud shown in the background is a little fuzzy to make it more difficult.














1. Cirrus spissatus, the only type of Cirrus allowed to have gray shading in the daytime. Note mammatus like feature in the center.

2. Contrail, unusually turreted one (hmmm, perhaps a part of some government conspiracy–hey, I am kidding the “chem-trail” people).  There’s also a patch of Altocumulus floccus (or  Altocumulus perlucidus would be OK, too) lower part of photo.

3. Cirrus castellanus-turreted Cirrus, don’t see that species too often because it is rarely so unstable at that height.  “Unstable”-the temperature dropped a LOT as you went higher up there, more than usual.

4.  Altocumulus floccus, horizon, upper right, Cirrus fibratus (pretty much delicate, straight fibers) middle.

5.  Ocotillo (hahaha, its not a cloud!)  ((Another example of the juvenile humor that the writer seems to be afflicted with).    OK, it looks like mostly Cirrus castellanus in the distance.

What do these kinds of clouds tell us?

The atmosphere is moist, but only patchy moist, a frequent occurrence in desert areas because “patchy moist” at middle and high levels in the atmosphere is most often all you get on the southern periphery of the major storms to the north of Catalina in the cool part of the year.

The atmosphere over us, too, is only in ascent at an overall rate of maybe an inch or two a minute; a bit more inside the clouds, less outside the clouds.  One way to KNOW how slight the air is rising, even in the clouds, is to observe that snow is falling out of some of them, tiny ice crystals, typically in the low hundreds of microns in maximum dimension (width of a few typical human hairs, which are about 100 microns in width.)  Such tiny ice crystals have fallspeeds less than 0.3 meters per second, and so they wouldn’t be able to fallout with higher overall “slab” lifting, the rate of that the whole upper air is lifting at these cloud levels.    Q. E. D.

What caused the lifting?  When you see clouds scattered over such a vast area, they have to be due to a disturbance in the wind field, a trough is likely nearby, normally upstream.

I have not looked at maps lately, but will NOW to see if there is a bend in the winds (indicating a trough) at these heights (mostly Cirrus level).  I don’t see one on the 300 millibar map (30,000 foot map) and so I am not going to show it.  But anyway, I am right, I am sure.  Now, I will begin a serious investigation to prove I am right.  The models will know if there is lifting going on.

Yes!  I have been saved in my assertion by my former employer, the University of Washington‘s MM5 model, and this was the first thing I looked at!    Look at the predicted high “clouds” (those above 20,000 feet) over Arizona for yesterday at 2 PM AST!  They can’t be there in the model unless it thinks the air is going up some.  OK, past the exultation stage now.  Moving on.  Actually, the model predictions of Cirrus-ee clouds aren’t really that great, so it was quite a surprise to see this.


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.