PURPOSE: To determine the characteristics of snow that make building a snow shelter possible.

MATERIALS: (per group): Suitable winter clothing, 2 snow shovels, thermometer, magnifying glass, brick, meter stick, data sheet and pencil. Optional -- black cloth (about 20 cm x 20 cm).

INTRODUCTION: Snow characteristics determine the kind of snow shelters made by native people in North America. The igloo was developed by the Inuit (Eskimos) of the arctic tundra. In this treeless land, the wind breaks large snow crystals into small grains. These small grains pack together with little air space when they fall to the ground. On the ground, this wind-driven snow (siquq) fuses together to form a hard, dense snow mass (upsik), which can be cut into blocks to build an igloo.

In tree-covered taiga farther south, the powdery snow (apun) remains loose due to less wind. In this environment, the Athabaskan Indians make a snow shelter called a quinzhee or powder snow cave. Loose snow from the ground is mixed and piled up to make a mound several meters high and wide. After several hours, the mound is hollowed out through a door near the ground.

In this activity, you will build a model quinzhee. You will learn how snow changes so that a sturdy snow shelter can be made out of soft, loose snow.

PREDICTION: Use what you know about snow to make a prediction about the hardness of freshly shoveled snow compared to shoveled snow allowed to sit undisturbed for several hours.

 1. A brick dropped from equal heights will sink deeper into which snow mound? Explain your ideas.

PROCEDURE:

A. On day 1, find a site with deep loose snow and no underbrush. The site should be away from possible disturbances. Mark off an area about 1 m in diameter.

B. Pile the snow in a mound using your shovel or snowshoe. Mix snow from the surface and bottom of the snowpack, lofting the snow as you shovel. Keep the snow light and airy; do not pack the snow. When you are done, the mound of snow should be about 1 m high.

C. Level an area about 30 cm in diameter on the top of the mound with the edge of the meter stick. Do not pack the snow down. This snow will become your old snow mound in 24 hrs.

D. Find an open location where the snow is level. Dig a hole in the snow to the bare ground that is large enough for you to kneel in and work. Along one edge, cut a smooth, clean, vertical section from the top of the snow to the ground.

E. Using the following method, measure the temperature of the snow 1 cm below the surface, midway between the surface and ground, and 1 cm above the ground. Use your pencil to make a horizontal hole at least 5 cm into the snow. Hold the thermometer in the snow for at least 1 min and read the temperature while the thermometer is in place. Record your data in the chart below.

F. On day 2, repeat steps A-C to make a fresh new mound of snow.

G. Drop a brick on end on the top of both old and new snow mounds from a height of 1 m. Measure how deep the brick sinks into each pile of snow. Record your data on the chart below.

H. Cut away half of each snow mound to the ground, leaving a smooth, clean, vertical section in each as shown in the diagram.

I. Measure the temperature of the snow in each snow mound using the method in step E. Record your data in the chart below.

J. Examine snow samples collected about 5 cm below the surface of both new and old snow mounds. Put the snow on the black cloth (or on a dark coat sleeve of a classmate) and examine with a hand lens. Record a description of both snow samples below.

MODEL QUINZHEE DATA

CONCLUSIONS:

2. What was the result of dropping a brick from equal heights into the fresh snow mound and the old snow mound?

3. How did your prediction compare with your data?

4. Use your data to describe how snow hardness and appearance changed in the snow mounds over a 24 hr period.

DISCUSSION:

5. Which of the three locations had the greatest temperature variation from top to bottom? Give one possible explanation for this result.

6. Which of the three locations had the least variation in temperature from top to bottom? Give one possible explanation for this result.

7. Water vapor within snow tends to move from cold snow to colder snow, freezing and fusing the snow crystals together. Use this information and your data to give one possible explanation for how loose snow from the ground that is mixed can get hard enough to make a sturdy snow shelter?