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Arctic Blast 2001

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"Weekly Topic & News" is posted here every Monday by 7 a.m. CST

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"The Weekly Topic and News" merges the expedition, educational goals, and the needs of teachers. It is the most important component of your online classroom expedition.

Start each week with an in-depth look at this page.

The topic of the week is emphasized with clearly presented, facts and information supplementing each unit of the curriculum package.

Information is also provided to help make real world connections, investigate personal values and discuss current issues.

Completing the circle, the weekly topic will also be highlighted from the Arctic Blast explorers.

Using the sights, sounds, and wilderness perspectives of the arctic facilitate meaningful and energized classes.

The Weekly Topic and News integrates the nationally accredited, K through 12, Nunavut curriculum package and the weekly reports from the expedition. This is where the adventure of collaborative learning really begins.

WEEK 15:
Amazing Snow and Igloos

One native Inuit says these words about snow and Igloo building, “In looking for snow for you to make an igloo you would look for snow that is more PUKAJAAK (Snow that has fallen later, after the first of the autumn. This snow is crispy and will not hold together)...” Snow is one of the most amazing compounds on the face of the earth. The solid form of water, snow exhibits many unique characteristics. For most plants and animals, the most serious problems of winter are associated with the extreme drop in temperature. Often, survival actually becomes dependent upon the snow cover. While it is the bane of plants that are covered by its heavy weight, as well as animals that must dig and scratch through layers to simply find food, it is the salvation of many plants and animals that depend on it for protection from the cold.

Every form of life is affected differently by the depth of snow. Even as little as an inch hides the daily movements of mice from the keen eyes of predators; this same depth also makes it difficult for other animals (pheasants, grouse, etc…) because it covers the seeds and insects that they eat. A slightly deeper layer of snow forms an insulating layer over the land, keeping dormant plants, insects, and small mammals protected from drying and chilling winds, yet allowing some of the sun’s light to penetrate. As snow becomes deeper, it creates new problems for animals. The character of snow is as important as its depth. Snow can be fluffy, wind-packed, wet, thinly crusted, glazed, or dry and drifting.

To some extent, the snow cover itself is influenced by the types of snow crystals within it. This influence is usually the greatest at the time of a storm. Snow crystals, once fallen, tend to change into similarly shaped ice granules. But as the snow falls the crystal type will determine how much the snow adheres, packs, builds up, or drifts.

Snow crystals form in clouds where temperatures are anywhere from 32 to -39F. To start growing, a snowflake needs a nucleus - usually a dust or salt particle. These particles attract water molecules from the cloud. The molecules continue to gather on the particle, freeze, and become ice crystals. This is the start of a snowflake or snow crystal. As the crystals become larger, they begin to fall, often hitting other crystals. The result is that part of the crystal breaks off and becomes the center or “nucleus” for another crystal. This often causes a chain reaction that starts other crystals growing. Temperature determines the shape and form of a particular flake. If the air is cold and there is little moisture, then very small, simple crystals are formed. Big and intricate flakes are formed when the temperature is warmer (just below freezing) and there is a lot of moisture.

Once fallen, snow goes through an aging process called destructive metamorphosis. It consists of the initial deterioration of a new snowflake to more or less rounded ice grains. Wind, temperature, and weight of new snow all affect this process. As snowflakes rub against each other or melt, space between flakes is reduced and individual ice grains will form new bonds (attach) to one another. The density and mechanical strength of snow increase during this process. (Compare a snowdrift with fluffy snow - a snowdrift has gone through destructive metamorphosis.) The principle of destructive metamorphosis is sole reason why the Inuit are able to carve snow out in blocks..

When snow stands long enough it develops layers. The top layer is usually sharp crystals. These are newly fallen flakes that have not been compacted, blown, or melted. Firn is the layer directly below the new flakes. These are crystals that are undergoing destructive metamorphosis and becoming more rounded and uniform in size. Below the firn is a layer called depth hoare. These are brittle, loosely arranged crystals formed from water vapor near the ground and in the snow. Between the depth hoare and the ground is a space called the subnivean air space. This space forms due to heat radiating from the earth. When looking for a suitable place to build an Igloo, the builder will probe the snow pack looking for the proper type of firn snow.

Fresh snow is nature’s best reflector turning back 75-95% of light striking its surface. As surface ages dust and dirt accumulate and reflective value drops to 45%. Snow is also a nearly perfect absorber of heat energy (long wave radiation). Evidence of this can be seen in snow-free spaces around trees, rocks, or even a person if they stood around in the snow long enough. Snow absorbs even the tiniest amounts of heat from any object and melts. Snow acts as an insulator and during the winter months, too and actually becomes a physical, protective barrier. The Subnivean Air Space is a snow free space (around 1”) between the ground and the snow pack. While air temperatures can climb extremely low, sometimes varying between -25 and -55, snow creates a stable environment below its surface and the air in the Subnivean will remain a comfortable 20 - 30 degrees F. The warmer air temperatures create open spaces near or at ground level that will eventually form labyrinths where many animals will spend their winters (at least in the non arctic regions that experience winter conditions), protect safely from the raging weather above. The fact that snow is an excellent insulator is also a great benefit to anyone living in an igloo.

Snow is amazing. It reflects light, absorbs heat, insulates, recrystalizes and changes... Without the unique physical and chemical properties of snow, the lives of the Inuit would be drastically different.

For more information about snow visit the following websites:
Snow Crystal Website
Snow Properties Website
Igloo Builders Guide
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