On the 17th August, not long before sunset, part of what seemed like a
large horizontal rainbow appeared beneath the clouds.

I took a photo of it, though to be honest the picture doesn't capture it
very well.

http://www.btinternet.com/~nickgardn...talrainbow.jpg

There was only part of the arc, but I am assuming that it would have
made a complete circle overhead given a cloud-free sky towards the
western horizon.

With the red of the setting sun, the colours of the rainbow were
obscured somewhat, but even so, you could make out the blue colours
quite well.

I've seen circumhorizontal arcs before but this was different in that it
was much larger and appeared directly beneath the cloud. Also the sun
needs to be high in the sky, whereas here it was just above the horizon.

I suppose it was caused by rain falling from the cloud, being lit up
from below due to the low sun, and the rain then evaporating quickly as
it fell towards the ground.
____________________________
Nick G
Otter Valley, Devon
83 m amsl
http://www.ottervalley.co.uk

On Aug 29, 1:22*pm, Nick Gardner
wrote:
On the 17th August, not long before sunset, part of what seemed like a
large horizontal rainbow appeared beneath the clouds.

I took a photo of it, though to be honest the picture doesn't capture it
very well.

http://www.btinternet.com/~nickgardn...lery/weatherim...

There was only part of the arc, but I am assuming that it would have
made a complete circle overhead given a cloud-free sky towards the
western horizon.

With the red of the setting sun, the colours of the rainbow were
obscured somewhat, but even so, you could make out the blue colours
quite well.

I've seen circumhorizontal arcs before but this was different in that it
was much larger and appeared directly beneath the cloud. Also the sun
needs to be high in the sky, whereas here it was just above the horizon.

I suppose it was caused by rain falling from the cloud, being lit up
from below due to the low sun, and the rain then evaporating quickly as
it fell towards the ground.
____________________________
Nick G
Otter Valley, Devon
83 m amslhttp://www.ottervalley.co.uk

?
Doesn't look very horizontal to me in your photo Nick.
I can see faint colours in an arc.

Len

On 29/08/2011 14:36, Len Wood wrote:
Doesn't look very horizontal to me in your photo Nick.
I can see faint colours in an arc.

The photo doesn't really do it justice and actually is a rather poor
representation of it.

Believe me, it was 'horizontal'!
____________________________
Nick G
Otter Valley, Devon
83 m amsl
http://www.ottervalley.co.uk

On the 17th August, not long before sunset, part of what seemed like a
large horizontal rainbow appeared beneath the clouds.
Looks just like the top of the arc to me.

http://i53.tinypic.com/abtvf8.jpg

shows the complete circle and, as expected, the bit on the left coincides
with the rainbow arc visible in your photo.

Nothing unusual as far as I can see, just a rainbow late in the day when the
sun was near the horizon.

On 29/08/2011 15:42, Darren Prescott wrote:
Nothing unusual as far as I can see, just a rainbow late in the day when
the sun was near the horizon.

Thanks for that Darren.

One thing to note though, the camera was pointing quite high in the sky,
maybe about 60° - 70°, not horizontally as it may appear in the photo.

Cheers
____________________________
Nick G
Otter Valley, Devon
83 m amsl
http://www.ottervalley.co.uk

On Aug 29, 1:22*pm, Nick Gardner
wrote:
On the 17th August, not long before sunset, part of what seemed like a
large horizontal rainbow appeared beneath the clouds.

I took a photo of it, though to be honest the picture doesn't capture it
very well.

http://www.btinternet.com/~nickgardn...lery/weatherim...

There was only part of the arc, but I am assuming that it would have
made a complete circle overhead given a cloud-free sky towards the
western horizon.

With the red of the setting sun, the colours of the rainbow were
obscured somewhat, but even so, you could make out the blue colours
quite well.

I've seen circumhorizontal arcs before but this was different in that it
was much larger and appeared directly beneath the cloud. Also the sun
needs to be high in the sky, whereas here it was just above the horizon.

I suppose it was caused by rain falling from the cloud, being lit up
from below due to the low sun, and the rain then evaporating quickly as
it fell towards the ground.
____________________________
Nick G
Otter Valley, Devon
83 m amslhttp://www.ottervalley.co.uk

Blimey I can't even see a rainbow let alone a horizontal version, all
I can see is an arc of a cloud line reflecting red.

On 29/08/2011 18:18, Lawrence13 wrote:
On Aug 29, 1:22 pm, Nick
wrote:
On the 17th August, not long before sunset, part of what seemed like a
large horizontal rainbow appeared beneath the clouds.

I took a photo of it, though to be honest the picture doesn't capture it
very well.

http://www.btinternet.com/~nickgardn...lery/weatherim...

There was only part of the arc, but I am assuming that it would have
made a complete circle overhead given a cloud-free sky towards the
western horizon.

With the red of the setting sun, the colours of the rainbow were
obscured somewhat, but even so, you could make out the blue colours
quite well.

I've seen circumhorizontal arcs before but this was different in that it
was much larger and appeared directly beneath the cloud. Also the sun
needs to be high in the sky, whereas here it was just above the horizon.

I suppose it was caused by rain falling from the cloud, being lit up
from below due to the low sun, and the rain then evaporating quickly as
it fell towards the ground.
____________________________
Nick G
Otter Valley, Devon
83 m amslhttp://www.ottervalley.co.uk
Blimey I can't even see a rainbow let alone a horizontal version, all
I can see is an arc of a cloud line reflecting red.

There's a rainbow there, all right - I have seen this sort of thing
myself. It is definitely *not* a circumzenithal arc. These appear
about 45 degrees above the sun and are amongst the purest of all the ice
crystal haloes with much brighter colours than any rainbow can produce -
once seen, never forgotten. The arc pictured is also plainly seen
against water drop cloud with the sun behind the photographer whilst
most ice crystal haloes are best seen looking towards the sun.

If you look closely at the top / right hand portion of the arc and your
colour vision / screen quality is up to it, you can distinguish yellow
and just a hint of green on the inside of the arc. Much of the short
wavelength light has been scattered away before the sunlight has reached
the water drops producing this rainbow, which is the reason why it is
overwhelmingly red.

--
- Yokel -

Yokel posts via a spam-trap account which is not read.

On Tue, 30 Aug 2011 21:11:00 +0100
Yokel wrote:

There's a rainbow there, all right - I have seen this sort of thing
myself. It is definitely *not* a circumzenithal arc. These appear
about 45 degrees above the sun and are amongst the purest of all the ice
crystal haloes with much brighter colours than any rainbow can produce -
once seen, never forgotten.

One I prepared earlier:
http://www.flickr.com/photos/5473150...7625183685100/

CZAs are neck-achingly high. 60-70degrees is /so/ much higher than
most people will, or can, look. I find that non-observers think that
50degrees is "vertical".

Looking at the original photo I think that the centre of the picture is
roughly 30degrees elevation, and agree that a rainbow in inconsistent
rainfall is the most likely explanation.


Mike