Journal Entries

2005-06

 

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January 15, 2006 — Palmer Station, Antarctica

Cool topic of the day — ICE!

We spent almost the entire day "island hopping" and had the perfect day to travel. The sky was overcast and gray, but the water was smooth and fairly clear of ice. Imagine having to maneuver your way in a little rubber Zodiac around massive icebergs, some as big as buildings! They look like gigantic blue ice sculptures floating in the water. Why are glaciers and icebergs blue? It has to do with how light is absorbed and reflected off the very dense ice crystals.

Antarctica (which is mostly rock) is almost entirely covered by a thick layer of glacial ice that is thousands of years old. As you know, ocean water is salty. Glaciers, on the other hand, are made of fresh water, in the form of compacted snow. The pressure of freshly fallen snow packs the lower layers of snow into thick layers of ice — the heavier and thicker the snow, the greater the pressure. These massive ice sheets are powerful enough to form mountains, carve out deep valleys, and leave a trail of debris in their path. The glacier that is in our backyard at Palmer is over 400 feet thick.

As the weather gets warmer here, the glaciers begin to melt and crack and break off into the ocean becoming floating chunks of ice called icebergs. When icebergs break off the glacier they are said to be calving. Calving sounds like thunder rumbling. Only about 10% of an iceberg is exposed above water, the rest is under the water. That's what the common phrase "it's only the tip of the iceberg" means — that there's only a small portion that is visible and the rest is unseen below.

Let's discuss the issue of melting icebergs. It's the topic of many discussions at Palmer because it's causing many problems. The most obvious is that the water level will rise. If you take a very full glass of water and pack it with ice so that ice is over the top of the water level, you have a mini-iceberg in a glass. Now let the ice melt and see what happens to the water level. The water in the glass probably spilled over the sides because of the rising water level — the same thing that is happening to icebergs in the oceans. Now make blue ice cubes by adding food coloring to the water in an ice cube tray before you put it in the freezer. When the ice cubes are put into a glass of clear water and let the ice melt you will see what happens when the freshwater icebergs (blue ice cubes) melt into the saltwater (water in the glass) of the ocean. The food source of many Antarctic animals (penguins and some seals) is krill, a salt water marine animal. It needs to live in salt water, but the melting glaciers are adding fresh water to the oceans, making them less salty. Not good news for the krill and they don't like it one bit. Some of the scientists at Palmer are studying krill and changes in their populations. Look here for more on glaciers.

More ice! There’s so much about ice because it is everywhere I look! I'll start from largest to the smallest kind I have seen. We already learned about the glaciers, which are the largest, and then icebergs. When an iceberg breaks apart and chunks crack off into the water, these floaters are called bergie bits.

Growlers are smaller than bergie bits and are clear, appearing black in the water. Brash ice is the smallest slushy ice that is a combination of other kinds of ice. Click here for more cool ice info!

All this talk about ice is making want my favorite treat — popsicles! I think I'll go scrounge around in the freezer here to see if they have any.

 

- Kaput-on-Ice

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