Wednesday, January 29, 2014

Chromatic Snow Sparkles

Looking at this photo that I just took, you might assume that it's a view of the stars and planets in the night sky, but it's not that at all.

It's a view looking down at the snow outside our breakfast window. The colored lights are sparkles of sunlight reflected and refracted internally inside snow crystals. Like a prism or a rainbow, the hexagonal crystals break the light into component wavelengths, giving the observer a variety of colors sampled from the rainbow: red, magenta, yellow, cyan, blue, and violet.

I took the photo with a digital SLR underexposed enough for the colored sparkles to register.

The conditions today are perfect for chromatic snow sparkles. It snowed three days ago, and has stayed below freezing since then, allowing the crystals to grow larger. This morning the temperature was five degrees Fahrenheit. 

It appeared to me that the colored sparkles are most pronounced about 45 degrees away from the sun. In the photo above, that band passes through the right central part of the picture, with the sun coming from the left. 

If you look at the sparkles on an angle farther away from the sun—or closer to the sun, the chromatic effect is much less noticeable.

Related previous post: Annular Highlights
Related topic: Sun dogs (rainbow effects on ice crystals in the sky near the sun)


Eugene Arenhaus said...

Whoa. I've recently been to Bulgarian Macedonia, and watched the snow sparkle in the mountains, but never really saw the rainbow effect like in these photos. Perhaps the angle was not favorable, or perhaps I was not expecting any colors.

Toby Haynes said...

That's an amazing photo. I'll have to see if I can replicate these shots with my Nikon camera here in Canada. Temperature this morning was -21'C so I don't think there is any chance of the crystals melting...

K_tigress said...

Nope I wasn't fooled at all but it is a neat FX representing the night sky.

Sometimes when I take a bath and the suds have settled some what on the surface it almost looks like I'm looking at a bunch of galaxy's and stars. I've been often tempted to take a pic of this and fix it up in PhotoShop, but then I have an after thought of accidentally dropping my camera in to the water.

James Gunter said...

I've seen the glittery snow sparkles many times, but never as dramatically as on the snow covered ice of Utah lake in the wintertime. When Ice covered, the lake has a very large, flat surface which I'll sometimes go for walks on, and have even plein air painted out on.

I've seen ice sparkles like the ones shown in your photos several times, but one day I learned why they angle away from the viewer in colorful bands like they do. They are trying to form a bow!

I've only ever seen it once in my life, but on one walk out on the lake ice a few years ago, I saw the chromatic snow sparkles form what looked like a complete upside-down "rainbow" on the snow covered ice, and a partial secondary bow! The bow extended a mile or so to the shore on my left and several miles to the shore near the base of the mountains to my right. The "ice bow" followed me around as I walked on the ice. I went out again the next day hoping to see it again, but although there were lots of colorful sparkles, the bow was no longer there. Sure wish I had had a camera!

James Gunter said...

I wrote about that ice bow here:

SO wish I had gotten photos, and yes, I WAS sober!

James Gurney said...

James, thanks for sharing that amazing description. I was surprised that I couldn't find out much about this on the web, and even Minneart in his great book "Light and Color in the Open Air" doesn't mention the chromatic qualities of snow crystals. He does talk about the behavior of hexagonal crystals in the winter sky around the sun, which forms sun dogs.

K. Tigress, that sounds wonderful, hope you can get the photo (with a waterproof camera?)

Eugene, I've seen this effect a few times before, but I always assumed it would be impossible to photograph. It took a little fooling around to capture it.

Toby, I used a Canon T3i at full resolution and about two stops underexposed. When the speckles go into bokeh, they get even more impressive.