07/31/2024
Glaciers, glaciers, glaciers!
I had such a wonderful time studying up before heading to SE Alaska to guide, and there were a LOT of things I didn't know about these icy wonders. A crash course, for those of you that like to learn while looking ;)
How they're formed: glacial ice is created in places where snow accumulates annually and does not melt. The weight of the newer snow pressing down onto the older, bottom layers causes a change in crystallization, eliminating air at each level of compression. As the crystalized snow grows larger and the air pockets between the grains grows smaller, the ice increases its density until only 20% air remains, mostly as bubbles trapped within the ice. The glacial process depends on temperature, weather, location, and time, so this process could take between 7-100 years. This ice is not consider a glacier, however, until the weight causes movement, where glaciers either grow in mass (advance), or shrink in mass (retreat).
There are several different types of glaciers, but to keep my post streamlined, I am going to focus on tidewater glaciers and the difference between them and hanging glaciers. Hanging glaciers are formed in inland areas (mostly cold, mountainous places) and advance or retreat within valley areas. Tidewater glaciers form in cold, coastal areas where the face of the glacier meets the ocean. Aside from SE AK, Scandinavia and Chile are the last places on earth that have true, tidewater glaciers.
Fun fact. The brilliant shades of cerulean and icy blues are the colors (wavelengths) of the light spectrum that are not absorbed by the ice, but instead, bounced back to our eyes. Places where calving or cracking in the glacier have occurred, reveal older, denser glacial ice (with only 20% air in it), causing the scatter of short-waved blue light.
Calving--was also awesome! I *may* have another video coming up where I caught a brief look!