After pulling up the photo of the cloud formation that looks like a circle with an X in the middle of it, I realized I had seen EXACTLY the same thing three or four years ago. I was driving on the 205 bypass around the south and east sides of Portland, Oregon on my way to my sister's in The Dalles in the Columbia River Gorge. Since the sky was a clear blue that day, I will assume it was summer, since skies that clear are rather uncommon in winter.
This formation was situated at approximately 1 o'clock directionally as I was traveling north. My first thought was, "How odd," and my second thought was that it was rather irresponsible for somebody to be skywriting practically on top of busy Portland International Airport, which is located along the Columbia River on the northeast side of Portland.
Since I had some time constraints, I didn't bother to stop and take pictures, even though I had a camera with me at the time. Nobody else seemed to find the sight that significant either, since traffic was moving right along and there were no gawkers pulled over to the side of the expressway to get a better look at it.
Knowing what time I usually leave on a trip to The Dalles, I would think it was probably sometime between 11:00 am and 1:00 PM. Now that I think about it, it was probably on a Friday, the third weekend in July, since that's an annual trip I take because of Rodeo weekend when my sister and brother-in-law host a big "do." I can't pinpoint it any closer than between two and five years ago, though, because I just can't remember. I don't know if a story about it ever made it into the Oregonian newspaper, but I suppose one could look up archival information for the third weekend in July for the years 2001 to 2005 to see if anything was written about this strange shape.
I remember wondering at the time how such a precise X could be made inside such a precise circle without any "overspill" of the contrail past the circle edge, as a plane would have to make some pretty big arcs to position itself to make the X. I was pretty impressed with the pilot's ability, even though I thought it was lunacy to be doing that kind of flying so close to a busy airport. I would think authorities would be out there looking for a person who had that much "moxie," and consequently, there'd be some type of newspaper coverage. By the time I came back from that weekend, I had completely forgotten about it, and didn't bother to look in the paper for any articles. Also, as I think about it, the formation seemed pretty high; probably too high to interfere with planes taking off or landing, but probably still some kind of violation regarding that particular airspace.
I also have to say that I didn't see any "object" like a pin doing the writing. As far as I could tell, whatever had made the design was long gone. It must have been one of those days when the winds at that height were relatively calm, because the design was still "intact," even though what had made it was no longer in the vicinity - that I could see - and I have better than 20-20 eyesight. Of course, since I was driving along at 65 mph on a three lane highway, I couldn't exactly concentrate too long at a time, and might have missed something that looked like a "pin" in the vicinity. I have a feeling that whatever made it was gone since the design was completely finished.
This may or may not be of interest to you, but I did find it coincidental that what your picture shows and my experience are virtually identical. It's difficult to compare in terms of size, but since I was closer to what I saw than the photographer was to the subject, it could be that they are roughly about the same. What I saw was more overhead, and therefore looked larger, but I think if the photographer would have been closer, it wouldn't be much different in size from what I saw.
Just for your interest.
source and references:
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