Cloud of the Week #2: Cirrus vertebratus

January 12, 2011 Maria

Cirrus vertebratus (photo by M. Ruth)

May I present the Cloud for the (mid)Week. This is cirrus vertebratus, a type of cirrus cloud resembling a spinal column or fish skeleton, hence the Latin vertebratus for vertebrae-like. Like other cirrus clouds, this forms high in the atmosphere, usually starting out as a smooth band of ice crystals that is then blown by crosswinds to create the fine filaments or streaks to either side of the "column." This cloud, remarkably, features a spine attached to a cloud that resembles hip bones! FYI: I did not PhotoShop this image.
These high clouds form at the same altitude as last week's cirrus radiatus--16,500-45,000 ft.--and usually indicate otherwise clear skies. They may however, thicken and begin a progression toward deteriorating weather.
Many of you took my "Head in the Clouds Survey" last month and identified the jet contrails in one photograph as cirrus clouds. I should have given you half credit for this answer, because contrails and cirrus clouds both form at similar altitudes and do look alike sometimes . I guess you could call a contrail a faux cirrus or psuedo cirrus (which is more fun to say out loud). Below is a photo of a jet contrail mimicking a cirrus vertebratus.

Jet contrail mimicking cirrus vertebratus (photo by M. Ruth)

In fact, this looks more like human vertebrae than the top photo. How do I know this is a jet contrail? Because I was watching the sky to the south of my home where I usually see jet contrails (heading north from Portland). I watched and photographed the deterioration of the contrail so I know this was not a naturally formed cirrus vertebratus. If such contrails formed amid authentic cirrus vertebratus, the identification would be trickier.

Real Ci ve (the official code) materialize in the sky gradually, almost imperceptibly, are irregular in width, and do not have a plane at one end (!) Jet contrails usually appear in the same sector of the sky (relative to your nearest airport), usually follow similar flight paths (mostly parallel, but with some criss-crossing), and are similar in width.

Though I have taken thousands of photographs of clouds in the past year, I would like to lure my readers to other websites where you can see thousands more. Click here to go to Clouds Online, a fabulous easy-to-navigate cloud atlas.

Next up: Tangled Cirrus