Glowing ice berg
This huge berg had just calved from a glacier into the Alsek River where we were rafting. While paddling in my kayak, I spotted this colorful berg with the green mountains behind it. This berg was over 100 feet long and about 20 feet high, with the majority hidden beneath the water.
One of the most interesting features of these bergs is their beautiful color. A simplified explanation of the color follows. The snow that falls on the glacier surface is full of many air bubbles. The bubbles create a huge surface for sunlight light to hit. As light hits the surface with all of the bubbles, most of the light reflects from this surface in about the same color as the incoming light, so the ice berg that calved from the relatively new ice appears white . As time goes on, the snow is both transformed and compacted. In this process, the air bubbles are crushed and become a very small part of the ice. Most of the incoming light does not reflect but rather travels through the ice, scattering as it goes. Red and yellow light is absorbed leaving the blues and greens to scatter and emerge as the predominate colors. The older compressed ice tends to be a lot bluer or greener than the younger ice for this reason.