Blue Atmospherics (Anti-Crepuscular Rays)

[sjwk0]

The night before last I popped out to the shops and saw a weird atmospheric condition that I'd never seen before: a deep blue stripe running from the horizon up into the sky.
It was probably about 9pm so still light but just starting to turn to dusk, weather was excellent, hot, mostly clear skies with a couple of wisps of cloud. It didn't move or change, but by about 15 minutes after I'd first seen it (most of which time I was driving to the shops while watching it), it had started to fade.
I didn't have a decent camera on me, but took a couple of photos with my phone (first time I've ever been glad I had a phone with a camera), so the quality isn't great.

Image1
Image2 (Both links dead; no archived version found)

Any thoughts? I'd guess this was looking towards the S/SE - there is a power station in that kind of direction but I'd guess this was a bit more to the East than the power station.

Oh, and the blue seemed to blot out the clouds rather than appear behind them.

Steve.

 

[uair01]

That's a wonderful picture, thanks for posting it!

My best guess is that it's a "anticrepuscular ray". The mechanism behind this phenomenon is explained here: http://www.sundog.clara.co.uk/atoptics/anti1.htm.

Archived version at the Wayback Machine:

https://web.archive.org/web/20060701133430/http://www.sundog.clara.co.uk/atoptics/anti1.htm

Another guess is that it might be a contrail shadow:
http://www.sundog.clara.co.uk/atoptics/contr1.htm

See this site to which these things moved: http://www.atoptics.co.uk

Whatever the explanation - you have photographed a very impressive occurence - with the stripe being so clear, thick and vertical. I'm constantly looking at the sky and haven't seen one like that before ...

 

[sjwk0]

Thanks for those links - they linked to another site that had a picture of sky polarization that looks another possible contender... the picture given on that page was through a polarizing filter that exaggerated the effect.

The anticrepuscular ray looked possible too, but I don't think it was a contrail shadow. There weren't any contrails for a start - although I guess if they were in front of the sun I might not have noticed.

Whatever it was, it was really weird to stand in the car-park and watch - and noone else seemed to notice it! I just wish I had a decent camera on me. The one in the phone seems to suffer from extremely bad vignetting.

Steve.