Look, Down on the Ground

Color and optical phenomena are all around us. But most folks never notice them.

I almost didn't notice this one. As can be seen in the two images above, the colors are subtle. But as I'm always on the lookout for such things I tend to notice these subtitles. Too often they turn out to be wishful thinking on my part. Wanting an effect to be that just isn't.

But not this time.

It helped that a fellow hiker had a different viewpoint and that his angle made the colors much more vibrant. Promoting me to take a second look.

This is an air bubble under the ice and above the water, or between two layers of ice. You can see by its changing shape that it is moving under top ice sheet. And notice the water drops under the top layer.

It is not clear what is causing the colors. Dr. Les Cowley of the go to site for this type of phenomena, Atmospheric Optics, suggested two possibilities, both forms of thin-film interference. The first, and the one I thought it might have been, is birefringence. 

The second is an effect that gives rise to the colors in soap bubbles. This one certainly seems more similar to my images. Whatever caused it I still think it is pretty cool that I got to see it.

Keep looking down!