Beautiful Antarctic Ice

I had seen lots of icebergs before, mainly in Alaska and Patagonia. But the number, size and diversity of icebergs in Antarctica was breathtaking. I’ll first provide photos of icebergs and then explain why they look the way they do. Icebergs calve from glaciers and I’ll show some glacier photos too.

From the boat we were transported to land via zodiacs twice each day: once in the morning after breakfast and once in the afternoon after lunch. Companies are only allowed to take 100 people to shore on each excursion. Our ship held 67 passengers, so everyone could go to shore on every excursion. On larger ships, passengers much take turns going to shore.

Sometimes, instead of landing, we toured the area on the zodiacs, giving us the opportunity to see the ice close up. This happened on our first day in Antarctica when we cruised around Brialmont Cove.

Brialmont Cove

Neko Harbor

On day 3, we set out on the zodiacs to land at Neko Harbor where a large colony of Gentoo penguins lives. However, the penguins decided it was time to make a mad dash to the sea and their numbers at the beach made it impossible for us to land and keep sufficient distance from them.

Paradise Bay

In the afternoon of Day 3, we took zodiacs to Paradise Bay where we could take photos in front a 7th continent flag. After that, we cruised around the bay in our zodiacs. From the boats we saw Brown Station, an Argentine base and scientific research station named after Admiral William Brown, the father of the Argentine Navy.

Turning snow into glacier ice

Snow is light and fluffy, and has a very low density. The density will be higher if the snow is wetter. If snow falls in a place where snow can accumulate from year to year, i.e., in polar regions or high-elevation mountains, the snow can turn into glacier ice.

Firn ice is snow that is at least one year old and has survived one melt season. Firn is transformed gradually to glacier ice as older snow is buried by newer snow falling on top of it and its density increases. Year after year, successive layers accumulate. Firn transforms to glacier ice at a density of 830 kg/m³. You know that ice is less dense than water, because it floats on top of water. As the ice gets older and denser, it approaches the density of water, which is 1000 kg/m³.

The process of turning firn ice into glacier ice can take just 3-5 years in very wet climates such as southeast Alaska. The transition occurs at a depth of about 13 meters (42 feet). In contrast, in the coldest, driest parts of our planet, including East Antarctica, the transition from firn ice to glacier ice can take up to 2000+ years and occurs at depths up to 95 meters (312 feet).

Why the blue color?

We see color when light reflects off the surface of an object. Some of the wavelengths of light may be absorbed by that object and we don’t see those colors. Any wavelengths that bounce off eventually reach our eyes, and we see the object as the color or colors that reflect back at us. White snow reflects all colors of light. One reason snow is so reflective is because there is so much air trapped between the snowflakes. Air bubbles scatter all wavelengths of light, making the snow appear bright white.

Over long periods of time, glacier ice is buried under new layers of ice and snow. These heavy layers press the air out of the deeper layers of ice. This removes much of the air and causes the ice to form large, dense crystals. When light hits these crystals, they absorb long wavelengths of light—the red end of the visible light spectrum. The crystals scatter short-waved blue light, which makes the ice appear blue. We can only see that blue color when we see the deeper layers of ice. This happens along the leading edge of the glacier, where the ice is calving, or breaking apart.

Now go back and look at the photos of ice above and think about the many years of history we are seeing when the blue-colored ice is exposed to our view at the leading edge of glaciers and in the icebergs that calve off of these glaciers.

Final note

See this web site for more information about blue ice: https://www.whoi.edu/ocean-learning-hub/ocean-facts/why-is-glacier-ice-blue/.

We have now safely returned to Chile from Antarctica and are hiking in Patagonia. We’ll continue on to Argentina in a few days. I have a lot more to say about Antarctica but may interweave current locations with more Antarctica posts.