K-Squared Ramblings

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.

Stringy Clouds at Sunset

Sunset on Tuesday, March 25th, with feathery cirrus clouds and contrails. A faint sundog is visible as a slight brightening at the level of the sun, about 2/3 of the way across the picture.

Sunset

View from the office parking lot earlier this evening:

Contrail Contrast

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.

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.

Corona

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.

Golden Lining

Friday, September 28:

Adding to the mish-mash of photo sources on here, this is a still frame from a video clip taken out the window of the car. It wasn’t supposed to be a video clip, but my camera has a sliding switch for selecting photo/video/review, and it has a tendency to shift while in a pocket or bag. *grumble*

Cobweb-cloud sunset

I stepped out of the office last Thursday (September 27—it was a good week for interesting late-afternoon skies) and saw this view to the west.

The clouds glowing as if from within, and the curved bands as if the whole set had been dragged across the sky, reminded me a bit of pictures of reflection nebulae.

Sundog

Spotted a sundog last Wednesday (September 26), about an hour(?) before sunset.

At least, I’m pretty sure that’s what it was, given the positioning, the brightness, and the reddish coloring on the end nearest the sun. The sharp edges of the reflecting cloud (a fragment of a contrail?) make it look a bit odd, though, like someone cut out a chunk of sunlight and pasted it into the sky.

Here’s a closer view from about a minute later.

I was following my usual photo-while driving method of pointing the camera in roughly the right direction, click the button a bunch of times, and hope a few shots come out. (Hooray for digital cameras, where you can delete a bad photo instead of wasting film!)

Rays of Light

Every once in a while, I manage to get a decent shot with my cell phone camera (currently a RAZR V3T).

Taken August 4 at 6:20pm. Cleaned up slightly to remove a digital glitch just above the cloud.

Invasion of the Lenticular Clouds!

I wasn’t expecting to see more after my last post on lenticular clouds. As I said, they’re (usually) rare in this area. But as I left the office Friday evening, I pulled onto the freeway and nearly freaked out at what I saw: A line of three smooth, layered clouds running above the ridge of the mountains to the north of Saddleback, and two more less-defined clouds picking up south of the peaks. I took the first exit and headed for a spot where I knew I could get an unobstructed view: a park in the Quail Hill area. (Knollcrest, I think.)

Click for a larger image

It was near sunset, and I was in a hurry to get some photos (not to mention a better chance to look at them!) before the light faded. You can see that the sun had already dropped behind the hill on which I was standing.

Click for a larger image

If you look at the horizon in the wide view, near the left at what looks like the base of the hills, you can see the orange balloon at the Great Park. I’m fairly sure they’d stopped taking people up by then, though I did see it airborne during my walk at lunch.

I’ve enhanced the contrast on these next few images, all cropped from the same photo to show close-ups (relatively speaking) of the three clouds:

I’m going to do something unusual here, and post an original-resolution copy of that contrast-enhanced photo, just ’cause it’s so cool. It compressed really well, to 170K, but beware—it’s still a 2,567 pixel–wide image.

Lenticular Cloud Over Irvine

One of the problems with photographing clouds is that you can’t run and grab a better camera. You have to shoot with what you have, or they’ll change configuration and quite possibly look completely different by the time you get back.

As I left for a late lunch today, I saw a set of half-discs stacked together, with a long trail stretching off to the left. We don’t see lenticular clouds that often in this area, so I stopped the car, grabbed my cell phone and aimed it out the window.

The Santa Ana Mountains are hidden behind the office buildings, and are probably the cause of the cloud formation.

Unfortunately, the detail isn’t that great. I tried to enhance the image a bit, but it looks like the brightest parts of the cloud overwhelmed the sensor. This is at the camera’s native resolution:

Update: Spotted some more interesting cloud formations later in the afternoon. Read the rest of this entry »

Contrail Shadow

With any luck I’ll finally post about last week’s trip to Las Vegas soon, but meanwhile, here’s something interesting that we spotted a couple of times on the drive back: The shadow of a contrail against the sky.

Here’s what it looked like, as the camera saw it. Actually, it was much more visible at the start. It faded considerably in the time it took to get the camera out and snap the photo.

And here it is with the contrast enhanced. You can see a dark line extending across the sky from the end of the trail down to the lower left. The sun was at the upper right, almost but not quite in line with the trail at that point.

Atmospheric Optics has a huge collection of cloud shadows, rays, rainbows, ice halos, and more, including a diagram of how contrail shadows work.

Two Sunsets

Just after sunset on Wednesday, February 7.

Just before sunset on Monday, February 12.

Comet!

The skies were surprisingly clear today. Four of us at work walked outside after sunset to a bridge near the office, and saw Comet McNaught. It was visible from ~5:10/5:15 to 5:28, at which point it slipped below the line of hills to the west.

We saw it against the red sky, slowly dropping through the (fortunately sparse) clouds. It was easily visible to the naked eye as a fuzzy white spot, with a hint of a tail pointing straight up that was a lot clearer in binoculars. The tail looked like a U or a V, fanning out at what looked like (but probably wasn’t) a 45° angle.

Well, my fingers are finally warming up. (I made the mistake of not grabbing my jacket, and went out just in my sweater.) Time to wrap stuff up.

Update January 13: I managed to catch another glimpse of it tonight. Unfortunately I was just arriving at the shop to pick up my car, and it was just closing, so I didn’t have a chance to watch it set (or see much more than a fuzzy white dot.) My watch said 5:02. By the time I got out, it had set beneath the building across the street, and there just wasn’t anywhere nearby enough with a clearer view of the western horizon.

On the plus side, I did manage to spot Venus while the sky was still light, and get a picture. It’s not quite as exciting as spotting it at one in the afternoon, but by adding more blue, you get an idea of what that looked like:

Update January 14:

I was looking over the photos I took last night (Saturday) and discovered I could actually find it by messing around with levels. On the left is the original photo, with a little bit of color correction to match what the sky looked like. The background’s still too bright to see the comet, though it was visible to the eye. On the right, I’ve adjusted the heck out of the image, and there’s a very slight bright spot right where it should be (I framed the shot so that the comet would be near the light pole, making it easier to find). Actually, now that I look at it again, it’s just barely visible in the less-processed photo on the left.

Also, this is cool: the comet has gotten bright enough to be spotted in daylight. (via Slashdot) I didn’t have any luck looking for it this afternoon, but I chalk that up to lower altitude and city haze.

Update January 15: I spotted something today, but I’m not sure what…