Why is glacial ice blue?
Glacial ice appears blue to us because all the colors of the visible spectrum (red, orange, yellow, green, blue, indigo, violet) except blue is absorbed by the ice. This blue color wavelength is transmitted which is responsible to make our eyes see the blue color of glacial ice. For this, the light has to move deep into the ice and other colors are absorbed but not the blue color. This is the reason why domes of ice appear blue. Whereas bubbly ice appears white because light is reflected even from the sides outweighing only the blue color and ice is in small short crystals with the air pockets which indiscriminately scatter the light striking it. When these air pockets that are trapped in the ice is pulled out during its travel through the river, ocean, or lake. Its size increases giving the ice blue color. The deepest blue ice is always found in the crevasses.
Others believe that blue color of ice is not because of Raleigh scattering but the reason why the ice is blue in color is same why the water appears blue. It can be because of the overtone of OH molecules stretch which will absorb the light at the red end in the visible spectrum.