blue ice

Blue ice is clean, compact ice formed in glaciers through the recrystallization of snow, often appearing in bands that suggest shear zones. It can also refer to coarsely crystallized ice found on the surface of seas and lakes.1

The blue color of ice, such as in icebergs and glaciers, is due to how light interacts with its dense structure. Ice absorbs longer wavelengths of light (reds and yellows) more effectively than shorter wavelengths (blues). The shorter blue wavelengths are scattered and reflected back, giving the ice its characteristic hue. The absence of air bubbles in dense ice allows light to penetrate deeper and enhances the visibility of the blue color, whereas ice with many air bubbles appears white because the bubbles scatter all colors of light equally.2