K-Squared Ramblings

Halo Triplet

While walking to lunch today, I spied a fragment of halo above the sun. (Whenever I notice a really thin layer of cirrus clouds, I always try to find an opportunity to block the sun and look for halos.) I tried to get a couple of shots with my phone, and figured I’d try enhancing them when I got home.

What surprised me is that the halo was not only still there after lunch, but clearer. On the way back, I stopped in several places with a building, or a sign, or a tree blocking the sun. The curve seemed too shallow to be a standard circular halo, so I wondered what I was actually seeing. Then I realized there was a faint halo inside the brighter curve, the two fragments meeting above the sun and splitting like diverging roads.

Then I noticed the sundog.

Three distinct sun halos. Not complete, and far from the clearest display I’ve seen, but certainly the most complex.

The brightest part appears to be the top of a circumscribed halo, which varies in shape from oval to kidney-bean depending on how high the sun is. You can just see the 22° circular halo branching off below it. Off to the right is a sundog.

It’s too bad I only had the phone, but it did manage to catch all three halos. I fiddled with the contrast a little to make them clearer, but they are visible without it.

And to think I saw this from the middle of suburban Southern California!

Sundog

Sundog, originally uploaded by Kelson.

Friday was a good day for atmospheric optics. I watched a sundog for most of my drive home.

Daily Halo Pics!

Just discovered there’s an Atmospheric Optics Picture of the Day! #

Glass Bow

The other day I was walking past a construction site in the Irvine Spectrum area, and noticed a rainbow-like ring appearing in the road. I immediately thought of this mystery photo on APOD and its (rather technical) explanation. Naturally, I had to take a picture myself.

It basically is a rainbow, except formed by reflections in tiny glass beads (used for sandblasting) instead of raindrops. The physicist who posted his (much better) photo to APOD had a better camera handy. And a linear polarizer. (Don’t you always carry one of those?)

Sadly, I only had my phone.

Halo and Shadow: Cloud Optics Two-Fer

Tree Halo, originally uploaded by Kelson.

Yesterday morning while driving to work, I looked up from the road and saw two parallel lines in the sky: One white, one dark blue. They were, of course, a contrail and its shadow on a thin cloud layer below. Because it was a thin layer, I started looking (when I had the chance) for fragments of halos.

When I finally stopped the car, I took a picture of the contrail and its shadow (now nearly aligned with the sun), looked up and saw a faint edge of a halo. I moved a bit to the left, putting a tree in front of the sun, and there it was: a clear 22-degree circular halo centered on the sun..

Christmas Shopping

• Need to sleep. Found myself typing “Satan Claus” by mistake. #
• Symptom of car culture: I almost feel like I have to justify crossing the street on foot to go to another store instead of moving the car. #
• Sun Halo. All you have to do is look up once in a while. #

• Linens & Things: Nothing left to sell but the shelves… #
• Almost. Walked around a corner and they do have SOME stuff left #
• Virgin Megastore is closing too, but they’ve still got lots of stuff. Incl 5000 copies of Serial Mom. #
• Replica toys: I get the nostalgia factor, but at the same time it’s a weird idea. #
• Going out of business sales seen today: 4. Mervyns, Linens&Things,Virgin,Steve&Barry’s. #
• And the more stores I look at, the more “What You Own” competes in my head for the ubiquitous Christmas music. #
• Amazon’s wishlist needs a generic option. Like “I want an 8GB Micro-SD card” rather than “I want THIS Micro-SD card specifically!” #

Halo & Sundog

While driving toward the sun a little after 1:00 this afternoon, I noticed a faint reddish, slightly upturned patch in the sky ahead of me, and realized it was probably the bottom edge of a 22° sun halo. I was surprised, since the cloud cover looked too heavy for it, but it was there. At the next intersection, I looked out the side window to see if I could catch anything above the sun, and there was a clear arc running left of the sun, from a little below sun level to as high as I could see.

We stopped the car, found a tree to block the sun, and both looked. There was so much glare it was easier to see with sunglasses on, so I lent mine to Katie so she could catch it. Finally I grabbed the camera and took a few pictures, most of them using a gate post instead of the tree.

We ran some more errands, and I caught up with her at the grocery store. On my way from the car, I looked up and saw a perfect bright sundog to the right of the sun, much brighter than the clouds around it and showing the full red-to-blue spectrum. I should have gone back to the car for the better camera, but I used my phone camera instead, and got this shot.

I got to the edge of the lot just as Katie was leaving, and immediately said something like, “Look! Right above that palm tree!” Then I took off my sunglasses, realized that it was completely washed out without them (though it seems to have come out all right on my cheesy phone camera), and handed them over again. It continued to be visible, though less well-defined (it was a lot sharper than this photo shows) for at least half an hour.

A circle around the sun, and a bright rainbow-colored spot in the sky. I wonder how many people walking around never even noticed.

Rainbow Feather Cloud

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.

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.

Halos and Rainbows and Clouds, Oh My!

Whenever 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.

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.

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.

Halo 360

As I was about to get into the car after lunch, I spotted a full-circle halo around the sun.

I’m fairly certain it’s a 22º halo based on the size. Read the rest of this entry »