Tag: sky

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Last Wednesday, on my drive home from work, I spotted a sundog on the way home from work. I finally snapped it when I pulled into the parking lot at Trader Joe’s.

The picture on the left was the best of the set, with the best contrast. The red is clearly visible on the end toward the sun, and the reflection is clearly brighter than the surrounding clouds. The one on the right is actually two minutes earlier, and isn’t as good — except that it looks like there are two sundogs (something I hadn’t noticed when I took the picture). Presumably there was a gap in the cloud of ice crystals, and one half or the other drifted out of alignment.

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On my way back to work after lunch today, I looked out the window and saw this feathery wisp of cloud with a clear rainbow pattern running from red at the the top to violet in the middle, then turning plain white below.

Feathery cirrus cloud banded from red to violet.

As I drove south, the colors moved down the cloud, disappearing entirely by the time I got back. By the time I could safely snap a photo, it was already more or less midway down the cloud.

I believe it’s a fragment of a circumhorizon arc, judging by the description:

Look for a circumhorizon arc near to noon near to the summer solstice when the sun is very high in the sky (higher than 58°). It lies well below the sun — twice as far from it (two hand spans) as the 22º halo.

The arc is a very large halo and is close to, and parallel to the horizon. Usually only fragments are visible where there happen to be cirrus clouds.

We’re still 2 months from the summer solstice, but it was 12:38 PM DST (half an hour before true noon), and the sun was apparently near 70.6° high. (The site is aimed at UK visitors, after all.) It also looked too far away from the sun to be part of the 22º halo, plus of course the colors were more well-defined.

This also points out the should-be-obvious fact that ice crystals can still form in the upper atmosphere even when it’s warm — say, 90°F — on the ground, so there’s no need to limit halo-hunting to winter.

I recommend checking out Atmospheric Optics’ additional pictures of circumhorizon arcs, most of which are more complete than this one. Some of them quite spectacular and must have been really impressive to see live.

Update: I spotted and photographed a much larger and more solid arc in May 2010.

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2 contrails and a shadow lit up against the morning sky.

I had to get up early today, early enough that I could still see a couple of stars (or more likely planets, but I’ve lost track of where most of them are right now). When I got to work, I was treated to the sight of these contrails lit up against the morning sky. The rising sun was still behind the mountains, below the frame.

Look at the cloud directly above the contrail on the right, near the leaves. You’ll see a dark nearly-vertical line, which I initially took for a contrail’s shadow, possibly even the one below it. A minute or so later, though, it looked like it might have actually been another contrail, one not lit up by the sun and therefore darker than the cloud behind it.

Oddly enough, half an hour later the entire area was blanketed in fog.

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Sun HaloWhenever there’s a light layer of cirrus clouds in the sky, I keep an eye out for halos. I catch the occasional iridescent cloud, or a faint sundog that’s only visible through sunglasses. Today I spotted a 22° halo as I walked back to my car after lunch, around 2:00pm on March 6.

It’s not as sharp as the one I caught 2 years ago, but there was more color. It was clearly reddish toward the inside and bluish toward the outside. Like last time, I didn’t have the good camera, just my cell phone, but at least this time it was a better phone!

This reminds me, our trip to San Francisco a few weeks ago was through patchy clouds, sun, and rain—perfect for rainbows. We spotted several, including one which was not only extremely bright, but actually showed supernumaries inside the band.

Rainbow along US 101

We saw this on Thursday, February 21, somewhere between Paso Robles and San Jose along US Highway 101. Katie remarked that it looked almost double-layered, I looked over, and said, “Grab the camera! It has fringes!”

I’d never seen, or never noticed supernumaries before. I’d never even heard of them until I was reading through Atmospheric Optics a few years ago. If you look on this color-enhanced picture (actually from another photo of the same rainbow), you can see several extra bands inside the violet arc, alternating green and pink.

Zoomed rainbow with supernumary bows.

The really weird thing? Classical optics doesn’t explain them. Refraction and reflection can only explain the red-to-violet band and the secondary bands that sometimes appear outside the main arc. These are actually wave interference patterns that occur if the water droplets are small enough.

On a related note, last Sunday (March 2) I saw what I’m fairly certain was a lenticular cloud, except it didn’t look remotely like a lens. It was just a long, narrow flat cloud floating above the Santa Ana Mountains. I noticed it around 3:00 in the afternoon, and a couple of very thin, also flat clouds above it, and thought it looked like the beginnings of the stack formation. What clinched it was the fact that the cloud was still there, 5 hours later (visible at night by reflected city light), despite the high Santa Ana winds. You know, after spotting two sets last summer, it looks like they form in Orange County a lot more often than I thought.

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Corona/Iridescent Cloud

Spotted this on Thursday, between rain showers. It’s a slightly distorted corona, formed by diffraction of sunlight around cloud droplets, splitting the spectrum and producing rainbow-like colors. According to the Atmospheric Optics site, the distortion indicates that the droplet size varies across different parts of the cloud.

This was shot through a window, and I’m 99% certain that the straight line running down the middle of the darker foreground cloud is a reflection from inside the room.