View from our back yard this morning. I had to tweak the colors a bit to approximate what it looked like to the naked eye. It’s still not quite right — there was a bit more pink in it, and maybe a bit less purple.
Sometimes it’s worth getting up at this hour.
On Monday evening, I looked out the front window and saw an unusually purple sky. I immediately went out to snap a few pictures, though the camera tried to adjust the exposure too much in most of them, making it really light. This one turned out very close to what I actually saw.
Since then, I’ve discovered (via Bad Astronomy) that it’s the result of volcanic eruptions in Alaska last month. The sulfur dioxide sprayed into the sky has been traveling around the globe, and made it to Southern California by September 1. More photos at SpaceWeather and kbaird.
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.
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.
Update: I spotted and photographed a much larger and more solid arc in May 2010.
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.
