Snow covers the ground 7 to 10 months of the year over the entire route of the Alaska-Canada Barrenlands Traverse. Most of the region is actually quite dry- - almost a desert, so the snow never gets much over 3 feet (about 1 m) thick.

There are really only 3 types of snow that we will encounter:

Windslab, depth hoar, and new or recent snow. Windslab forms where there is a lot of wind, typically on the tundra. The wind blows the snow about pulverizing it and breaking the snow grains into small fragments. Because these are so small, they bond to each other (a process called sintering), making a hard and cohesive slab. Some wind slabs are so hard the only way to shovel them is by sawing them into pieces first.

Depth hoar is snow that has been sort of "cooked" after it is on the ground. Throughout the arctic, the ground is much warmer than the air in winter. Water molecules like to migrate from the warm to cold, so there is a constant upward migration of these molecules all through the winter. Molecule by molecule, bit by bit, all of the snow crystals are regrown. By mid-winter there are only 1/10th as many crystals, but these crystals are much bigger...some as large as 3 cm (1.2 inches) long. They are also very beautiful.

The last type of snow is the new and recent snow (just a few days old). This is what most peole think of when people say snow crystal: a beautiful 6-sided star. However, there are many other types of crystals that fall from the sky, like the capped-column shown below and to the right.

There are lots of ways to explore snow crystals. For new crystals, try going to:

http://www.its.caltech.edu/~atomic/snowcrystals/

Better still, if you live where it snows, go outside when it is snowing and look at the crystals on your jacket sleeve with a hand-lens.

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