Mysterious Lunar Ring in the French Alps

[opsb]

I was in the French Alps the other day, high in the mountains (not sure if this is relevant), and, on the night of a full moon, with mist in the sky, there was a circular ring of light around the moon.

The ring subtended an angle about 5 times that subtended by the moon (that is to say, it looked about 5 times as wide as the moon), and, the colours were split up (though not as well as in, say a rainbow - they sort of merged together a bit).

The inside colour was (I think - may have forgotten) red.

Rainbows appear on the 'other side' of the sun, due to the geometry of the spherical raindrop, so it certainly wasn't a standard rainbow. Also, it subtended far too small an angle (I could easily see the whole ring, with the moon at the centre)

Any ideas what was happening?

 

[jmatejka]

We called these "Sun Dogs" in Colorado.

http://en.wikipedia.org/wiki/Sun_dog

A "moon dog" in your instance.

 

[opsb]

Thanks, that's pretty interesting.

 

[jmatejka]

Thanks, that's pretty interesting.

Your welcome, I would ocassionally see sun dogs in Colorado Springs.

 

[Naty1]

Sounds like you were observing a ring of colors analogous to a rainbow..
try here
http://en.wikipedia.org/wiki/Atmospheric_refraction

and also note optical dispersion...

basically, different colors are refracted (bent) at slightly different amounts so the colors get separated and spread out...like a prism disperses sunlight...the degree of bending is dependent on atmosphere conditions like density, humidity, particles in the air,etc.

 

[opsb]

Naty1 - I'm not sure this accounts for the ring. Look at http://en.wikipedia.org/wiki/Sun_dog , posted by jmatejka. That seems to match up perfectly with what I saw. The similarities of the visual description I gave to the one in the article is actually quite uncanny.

 

[Evo]

I was in the French Alps the other day, high in the mountains (not sure if this is relevant), and, on the night of a full moon, with mist in the sky, there was a circular ring of light around the moon.

The ring subtended an angle about 5 times that subtended by the moon (that is to say, it looked about 5 times as wide as the moon), and, the colours were split up (though not as well as in, say a rainbow - they sort of merged together a bit).

The inside colour was (I think - may have forgotten) red.

Rainbows appear on the 'other side' of the sun, due to the geometry of the spherical raindrop, so it certainly wasn't a standard rainbow. Also, it subtended far too small an angle (I could easily see the whole ring, with the moon at the centre)

Any ideas what was happening?

It's a halo. More specifically, yours sounds like a corona.

http://home.hiwaay.net/~krcool/Astro/moon/moonring/

I witnessed a very rare event where the halo started out as a very small ring right around the moon then continually grew bigger until it filled the sky. It made the news. Supposedly the rings do not move.

http://curious.astro.cornell.edu/question.php?number=79

I also witnessed an incredible hot pink sun pillar. I have never seen a pillar of the size or intensity of the one I saw, and of course not a single camera had a working battery. First and last one I've ever witnessed.

 

[broean01]

It might be a 22 degree halo. These rely on ice particles in the air, so it makes sense that you would see it in the alps.

http://en.wikipedia.org/wiki/22_degree_halo"