Trick and treat sunset yesterday evening

Late yesterday afternoon, the sun appeared to be setting in the wrong location, about 20-25 degrees south of where it is supposed to be at this time of year.  Perhaps something horrible had happened, I thought.  Retirement with a happy ending here in Arizona was too good to be true, I thought, and now it was all going to come to an end.  First, some perspective on where the sun was going down BEFORE yesterday.   This first shot was taken just a few days ago (Feb 13th).  Note where the sun is relative to the Tortolita mountains on the right, and Twin Peaks, the two itty bitty humps to the left.  For further perspective, at the winter’s solstice, December 21st, and from this same location, the sun sets next to Twin Peaks.   So,  in this first shot you can also see how much the sun has moved in two months.

But then yesterday, something awful seemed to be happening.  The next photo was one to send chills down your back, and in fact, if the sun was setting over there in the winter as a matter of routine, the northern hemisphere would likely glaciate down to about Blythe in the winter, due to the NH sunlight being so weak (that is, with so much tilt of the earth’s axis about which it spins).   The days here would, in that case, be about the length of those in Seattle with daylight only from about 8-4 PM in the wintertime because the sun would be taking such a low trajectory in the sky;  would rise late and sink early.


So, while I was concerned with the earth-sun system and some kind of apocalypse yesterday evening, I have feeling that most people were thinking, “Well, I guess we’re not going to have such a great sunset.  Seems to be too many clouds over there where the sun is setting.”

Or maybe you were thinking about that important Washington Husky  Arizona Cats basketball game today and how it might go.

But “No!”, a little later the sun underlit all those clouds, appearing to have sunk in its proper position for this time of year (3rd photo)!

I felt relieved and started thinking about that important Washington Husky -Arizona Cats basketball game today and how it might go.  Then I also started thinking about how I might have been the ONLY person to notice something was terribly WRONG with that sunset.  I feel pretty good about that part.

So, what happened?  This “trick” sunset, followed by a treat of a sunset was caused by a parhelia (explanation by my friend, Bob, here) whose accessible name is “sun dog” or “mock sun”, which we CERTAINLY had in this case!

Parhelia appear, if you don’t go to the site above for a more complete explanation,  when the ice crystals in the cirrus clouds up there are hexagonal plates, and fall with their faces down.   The sun’s light is refracted (bent) as it passes through jillions of these plates and at about 22 degrees from the sun’s position, an observer on the ground will see a bright spot, sometimes with a little coloration.  Sometimes there is also a “22 degree” halo along with the sundog.

I should add that the “trick” parhelia was being produced by ice crystals in the cirrus clouds above and behind the altocumulus cloud deck yesterday.  Of course, as you know, altocumulus clouds are comprised completely or mostly of droplets and cannot, therefore, produce parhelia.

Finally, to end, the last shot is almost at the winter solstice, taken on December 26th, and has a parhelia, aka, sun dog, mock sun, at left so you can see what they usually look like and how far away from the sun they are near sunset.   Yesterday’s, though, I thought was astoundingly bright and really made it look like the sun was going down in the WRONG place.


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.