Glacier fronts and icebergs sometimes appear blue or present veins of beautiful blue ice. The blue color is determined by the large ice crystals and the absence of air bubbles. When snow falls on the ground it accumulates in layers containing a lot of air. As the snow compresses and ages the air is squeezed into smaller bubbles and ultimately the air can be squeezed out of the ice. This is what produces the blue color in glacial ice at any latitude. Blue ice photo by Chris Marquardt