The color and hue of an iceberg depends on the amount of snow particles and air bubbles in the glacier ice.
Icebergs are stunningly beautiful natural wonders that have captivated the imagination of human beings for centuries. The pure, crystalline ice that composes them can take on a variety of hues, ranging from brilliant white to deep blue, depending on the depth of the ice and the angle of the sunlight. Their majestic size and shape are awe-inspiring, as they can tower hundreds of feet above the ocean's surface and stretch for miles across. The color of these natural structures can also be green or blue, and they could even be striped, per ABC.net. Professor Steve Warren of the University of Washington told the outlet, "Most icebergs are white — with a hint of blue."
The reason for this is that icebergs consist of snow and "glacier ice," which is essentially snow that has been compressed. Although a small proportion of light is reflected off the surface of an iceberg, the majority of it penetrates into the iceberg and interacts with the snow particles and air bubbles contained within the glacier ice. When light encounters snow particles or bubbles within the iceberg, it is refracted and diffused due to the boundary between the ice and air.
In cases where there is a high concentration of bubbles and snow particles, all the wavelengths of light are diffused before being absorbed, resulting in a brilliant white appearance. On the other hand, when there are fewer bubbles present, the chances of light being diffused decrease. In the case of ice, this causes red wavelengths to be absorbed, leaving only blue light to scatter and give the iceberg a blue color. There are, however, a few icebergs that sport rare colors and unique patterns.
Some of the most mysterious icebergs in existence can be found in Antarctica. Icebergs with a deep green hue resembling jade or emerald have confounded ship captains for nearly a century. Professor Warren said, "They are so immediately obvious when you are just looking at them because they are dark and clear. You can see 10 meters down into the ice." Unlike glacier ice which contains bubbles, these icebergs are transparent. They are created from frozen seawater that attaches to the bottom of the floating ice shelf above, resulting in a bubble-free structure.
The color of "marine ice" can vary, ranging from blue to green, depending on its composition. Professor Warren said, "Marine ice contains not just ice but tiny particles that give it color. The exact color of these marine icebergs will depend on how much organic matter and iron oxide was in the seawater at the time." Antarctica is also home to one-of-a-kind striped icebergs. These are formed by seawater seeping into vertical crevices that form on the ice shelf as it separates from the landmass. The cold, light-colored glacier ice allows seawater to infiltrate, resulting in a dark stripe when the seawater freezes. According to Professor Warren, not only are icebergs aesthetically pleasing, but they can also provide valuable insights for scientific research.
Examining icebergs can aid in elucidating the mechanisms that transpire at the base of ice shelves, such as the speed at which fissures develop. Furthermore, it can contribute to our comprehension of how crucial substances, like iron, are dispersed throughout the Southern Ocean. Professor Warren explained, "Ideally, it would be nice to be able to know, just from the color of an iceberg, what's in the ice — and how important it is to contributing nutrients to the Southern Ocean. We never would have proposed to study icebergs previously. We thought they were just an exotic curiosity — just for fun. But now, many years later, we think maybe they deserve a dedicated study."