Why does ice sometimes appear to be blue?
Ice can appear to be blue because the red (long wavelengths) part of white light is absorbed by ice and the blue (short wavelengths) part of light is transmitted and scattered back to the viewer. The farther the light travels through the ice, the bluer it looks. Without the scattering effect of air bubbles, light can penetrate ice undisturbed. In this photo of the Lower Falls, the blue ice has fewer air bubbles in it than the white ice. Have you seen any blue ice in Yellowstone National Park?
Information and feature photo provided by Yellowstone National Park on social media. Above photos by Brian Emfinger.