Sunrise and Cirrus splendor; the rarely seen Cirrus castellanus floats by

Gee, three days with a cloud or two over droughty Catalina!   Yay! Here’s yesterday morning’s nice Cirrus uncinus (icy clouds with long trails).

Then, later that morning, the RARELY seen Cirrus castellanus sporting some mammatus (downward protuberances at the bottom) showed up.  (I should note that some of the female atmos sci students at the U of WA preferred to call “mammatus” varieties, “testicularis”.)   I mention this in defference to their preference.

These icy Cirrus clouds, whatever you call them,  are probably the rarest of all Cirrus.  The noticeable cumulus-like shape shown in the second photo is rare up there.   Mainly a steep drop in temperature with increasing height up toward the top of the troposphere (the earth’s blanket of air that contains our clouds (moslty).

Turrets, or cumulus-like shapes in clouds like the “puff” of Cirrus in the middle of the second photo, are also thought to be driven by the release of the latent heat of condensation (in lower, warmer Altocumulus clouds) and latent heat of deposition in ice clouds).  When condensing droplets or as an ice crystal, heat is released to the atmosphere.  This is a HUGE factor in thunderstorms (a lot of heat is released during condensation in updrafts), frequent in cooler,  mid-level clouds such as in Altocumulus castellanus, but,  because there is so little water vapor at Cirrus levels, very unusual way up there.     Yesterday’s cloud were likely forming around -40 C,  at about 33-34,000 feet above the ground.

Below the Ci cas photo is a sounding from the folks at the U of WY.  It hints at a steeping of the lapse rate just above the 250 millibar level (between the 200 and 300 on the left side), and also just below a stable layer  or sideways “v” in the temperature trace up there.

I was quite pumped to see this rare display.   Out of thousands of cloud photos, I have but a dozen or so of Ci cas.   Unfortunately, it seemed, passersby in the Basha’s parking lot when this was about to go overhead, were non-plussed when I pointed out the unusual cloud.  They were mostly polite,  but generally said something like, “Huh?”  It made me wonder what is happening to us if we can’t get excited about a Ci cas?  I started to feel sad.

Later, in the afternoon, when the heavy ice clouds moved in (Altostratus translucidus and opacus) in the late afternoon, you probably were guessing that a good sunset was on tap.  And you were right.   Below an example of that Altostratus, followed by another neat sunset.   Likely to repeat all this today.

Hey, get excited!














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.