Tag: halo

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Halo Towers

I developed an interest in sun halos a while back. Bright rings and arcs can appear in the sky when ice crystals are lined up just right with your viewpoint, much as a rainbow forms when water droplets are lined up just right.

You see a lot more of them, and especially the most spectacular ones, in colder climates where ice crystals form more often. But I still see several circular halos and sundogs each year even in Southern California, particularly when there’s a thin layer of cirrus clouds. The ice crystals only need to be in a line of sight, not near the ground.

The arc at the top of this photo, looking like it’s bridging the two buildings, isn’t a rainbow — the colors are wrong and too pale, and it’s in the same direction as the sun (which is behind the building on the left). I think it’s a 22-degree circular halo, but I’m not certain. It looks a little bit too shallow, so it could be a tangent arc, but I’m not sure the sun was quite high enough for it to point downward from the tangent instead of upward.

Here are some other sun halo photos I’ve posted on this blog in the past.

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I got off the freeway to catch the train out to the office last Tuesday morning, and saw this incredibly bright sundog off to the east. I couldn’t get a parking space, so I had to drive the rest of the way, but I did get a couple of photos.

The sun is off-frame to the right.

I’m not sure why the bright patch was so elongated and well-defined. My guess is that a smaller cloud in the foreground happened to be in exactly the right spot to reflect the sunlight.

I had to shorten the exposure in order to actually get some detail on here, like the bit of color spectrum in the middle.

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I saw this amazing circumhorizon arc around 1:30 this afternoon. I had just crossed the street while walking to lunch when I looked up, saw it…and walked back to the office to get my camera!

Lesson learned: always bring the camera!*

It started out as just a couple of small segments, but as the clouds drifted into position it quickly grew, and at its strongest it was just long enough to fill the field of view on my camera. There were also a couple of fragments of a 22° circular halo visible at the time.

The whole thing had vanished by 1:50, as the clouds drifted out of alignment, though I did see a more complete circular halo later on.

It looks like a sort of straightened-out rainbow, but it’s actually caused by ice crystals. If the right type of crystals cover the entire sky, this will actually stretch in a circle all the way around the sky, parallel to the horizon.

They’re a lot less common than the 22-degree halos. I’ve seen and photographed a ton of those over just a few years, but this is maybe the second time I’ve seen something like this. Fourth if you count the two feathery fragments I’ve seen.

At times like this, I really wish I had a DSLR, but the point-and-shoot will do in a pinch.

*On the other hand, when I went back, I pointed it out to a couple of people at the office who are into photography, since it was visible through the windows on one side of the building. One of my co-workers has a digital SLR and carries it with him, so he went outside and got some great shots. If I hadn’t taken a late lunch and chosen to walk anyway and been in the habit of looking for halos and forgotten to bring my camera, chances are no one in the office would have seen it.

Update (May 17): I just discovered that there are people who think these clouds are connected to earthquakes. No, they aren’t. They’re caused by ice crystals refracting sunlight, just like most halos, and have been seen in many places that didn’t have earthquakes.

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A mosaic of four photos I took this afternoon of a full 22° halo around the sun. It was extremely hazy, and the halo was almost impossible to see without sunglasses because of the glare. I actually stopped the exposure down in order to get the halo.

A few minutes earlier (and a few miles away) I also saw a faint fragment of a circumhorizontal arc. Oddly enough, it was the same time of day, time of year, direction of the sky, and stretch of road as the last one I saw! If I drove that stretch of road regularly, I wouldn’t be so surprised, but I’m only rarely in that area at lunchtime.

Update: About a month later, I saw a really clear circumhorizon arc (or rainbow cloud)…from my office building’s parking lot!