BLUE ICEBERG Blue is the natural iceberg color, because ice absorbs more red light than blue, leaving mostly blue to reflect back at our eyes. Doug Knuth [CC BY-SA 2.0 via Wikimedia Commons)
WHITE Most icebergs look white instead of the natural blue because dense snow is tightly packed on them. Snowflakes reflect all wavelengths of light equally, creating the sparkling white color. Lurens Pixabay
BLUE CREVASSE Evidence that icebergs are typically blue, unless they are covered with hard white snow, can be found simply by walking on a glacier and peering into a crevasse--which will appear blue. MB Photography Getty Images
JADE Colors other than blue and white can form when cold seawater freezes onto the underside of an ice shelf that extends from land over the ocean. If an iceberg breaks off and rolls over, the “marine ice” on the underside shows. Particles in the frozen seawater create different colors; dead organic matter makes the berg look green, like this one in the Australian Antarctic Territory. Auscape Getty Images
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DIRTY BERG Rubble picked up as a glacier grinds over land can create dark stripes in the ice. Echo Images Alamy
STRIPED ICEBERG Colored stripes can form if cracks open in the base of an ice shelf and become flooded with seawater that then freezes. Franz Lanting Getty Images
BLACK BERG Shiny black icebergs are large hunks of flawless frozen seawater; lack of internal cracks means the ice absorbs all wavelengths of light without scattering any back out. Arthur Greenberg / Alamy
COLORLESS CUBES Large slabs of ice absorb incoming red light and reflect blue, which is why they appear blue. Small ice cubes made in a freezer have no hue because they are just too small. The red wavelengths pass through almost as much as the blue ones do. Hans Pixabay
