TOPICS:  Crystal structure, weather, heat transfer.

LEVEL:  High school

TIME:  One period for field work, 15 minutes for lab work (graphs can be done at home); additional time before and after procedure for discussion of predictions and results.

ADVANCE PREPARATION:  Construct snow scoops from soup cans with both ends removed; an optional wooden dowel handle may be attached with bolts.  If you plan to do the GOING FURTHER activity, begin collecting daily weather information from the newspaper several weeks in advance.  This activity works best when the air temperature is well below freezing .

NOTE: You may wish to use the Inuit (Eskimo) Snow Terminology sheet from the Snow Terminlogy activity .

PREDICTIONS:  In class discussion, encourage creative, logical, and critical thinking. We recommend that you introduce the following ideas if they are not suggested by students:

(1)  Soil under the snow is usually warmer than average winter air temperature, so the snow at the bottom of the snowpack is usually warmest. (2)  Snow density is variable.  A newly formed uniform snowpack tends to be more compact near the bottom due to weight of snow above.  The bottom layer in an old snowpack is often less dense due to the movement of water vapor upward toward colder snow in the snowpack .

STEP I.  If the snow is too hard to use the scoop, have students cut a rectangular piece of snow with a snow shovel and measure its volume with the meter stick .

LAB PROCEDURE: Store snow samples outdoors or in freezer for lab analysis on another day if necessary .

STEP L. Volume of a Campbell Soup can is about 365 cm³.

QUESTIONS 5-8 require higher-order thinking skills.  We recommend that you discuss these questions in class before having students write out their answers .

3-4.  Answers will vary .

5.  The air temperature directly influences the layer of snow beneath it just as the soil affects the snow layer above it .

6.  The bottom layer of snow is often less dense because it is warmest.  Cold snow loses water vapor (mass) to colder layers above, increasing air spaces in bottom layer .

7. See sample graphs .

8.  Air temperature 1 cm above the snow will usually be closer to the temperature of the top layer of snow if the air is calm.  Possible explanations for the difference in air temperature at the two locations include heat exchange by radiation and conduction between the air and the snow, wind speed, and snow thickness and density .

GOING FURTHER:  See Snow Teacher Background.