Now here’s something I have NOT seen before, which is pretty hard to have happen after decades of photographing the sky. Here’s what I saw around 1:30 PM yesterday over Catalina. I took three photos starting at 1:27 PM, 1:31 PM and 1:37 PM. Here they are:
So, how to explain this odd “stitched” contrail? Well, we can start with a few “facts” and hypotheses concerned with the aircraft and its crew.
1) Of course, with today’s modern instrumentation, pilots no longer have to actually fly commercial jets anymore. They simply set their destination with their Tom-Tom GPSes; flight levels and so forth, and then go to sleep until near landing time when they have to wake up again to be sure the automated process is still working. Perhaps when I took these photos, the flight crew was napping and the plane was kind of zig-zagging around that bit, I’m sure to the amusement of the passengers, who probably needed some excitement anyway to distract them from their cramped quarters.
2) The pilots WERE flying the plane, but weren’t focusing on the task at hand, but were distracted while talking about stuff, maybe sports; perhaps recounting the great classic Superbowl game matching up two historic Rust Belt sports franchises, the Packers and the Steelers.
3) Since alcoholic beverages are available on flights, perhaps the pilots had some beer and while not necessarily really drunk, weren’t able to fly in a straight line.
Personally, I reject all of the above. They appear to be “strawmen”, the result of superficial thinking strictly for entertainment purposes rather than having any intellectual depth.
Now for the “WHAT” part.
4) There are rarely seen regular undulations in the higher cirrus clouds in these photos, amazing ones really. These reveal waves pretty much perpendicular to the wind direction. The flight track is along the wind (tail wind). These waves in the atmosphere are like gigantic ocean swells, usually occurring where there is an noticeable increase in the wind with height.
Could these waves have produced this stitched pattern? I am thinking “yes.” That aircraft was likely close to the bottom of those cirrus (undulatus) clouds, and was SURELY experiencing those atmospheric waves, and likely exciting the passengers who probably needed some excitement to distract them from their cramped quarters-worth repeating.
We can’t tell here whether the contrail is rising and falling as would be happening in the cirrus lines and between them, respectively, or whether there is a perturbation to the horizontal winds associated with those waves. A time lapse would be great here, and here’s one though it had some problems yesterday, from the University of Arizona’s Atmospheric Science Department. A part of the contrail moves into the time lapse frames at 1:30 PM over Tucson, and from this angle, looking toward the Catalina Mountains to the N-NE, it does give an impression that the contrail was rising and falling. Confidence is low here, though, in that description.
Here’s the last shot as this phenomenon and cirrus waves raced over the east horizon. This last one makes it appear that the horizontal winds fluctuated more than the vertical winds under these waves producing a zig-zag in the horizontal.
With all the wonderful cirrus clouds around yesterday after a long absence, we had another one of those memorable Arizona sunsets, see last photo.