The Inuit people of Canada and Alaska lived in igloos constructed of packed snow. Snow caves dug on hillsides or in piles of snow can protect one who spends a winter night outside by choice or in an emergency. Chipmunks, insects and numerous plants survive subzero temperatures underground, insulated by snow cover. How can snow protect life from freezing temperatures? The answer is that a fresh snowfall contains 90-95 percent trapped air between the snowflakes, so a layer of snow 10-12 inches deep can insulate the ground from freezing air temperatures. However, a light snowfall may allow the ground to freeze to a depth of a foot or more. Also, a layer of snow protects plants, animals and humans from the wind chill factor and prevents body heat from radiating off into the air.

Since February set records for low temperatures and snowfall was plentiful in Western New York, I decided to see for myself how effectively snow insulates. In my experiment, I used my Sharp Company atomic clock indoor/outdoor thermometer transmitter to record outdoor temperatures on my porch and under a snow pile on the ground by the front porch. Results for typical days are displayed in the chart.

Interestingly, the temperature at ground surface stayed uniformly between 26 and 29.7 degrees regardless of the air temperature. On Feb. 28, when the air temperature was minus 13.5 and the ground temperature under the snow was 26.5, a 40 degree difference occurred, indicating a most efficient insulating effect. On March 10, when the air temperature rose above freezing to 44.7, the ground temperature stayed below freezing at 30.4, confirming an insulation effect. Just how good is snow as insulation? Building insulation is given an R rating, which is a measure of thermal resistance to conduct heat or cold. A higher R value indicates less heat loss. By comparison, fiberglass R value is 3.5 per inch thickness, cellulose/pulverized paper is 3.7, thinsulate clothing ranges from 1.6-2.9 and glass is 0.14. Snow is only rated as a 1, but 1 is better than none. That is why with a light snowfall of only inches, the insulation effect is minimal so the ground freezes sometimes to a depth of a foot or more. In northern climates of the United States, attic insulation should have an R value close to 40. Therefore, if fiberglass insulation is used, at least 10 inches of depth is needed (40 divided by 3.7 equals 10.8) placed between floor joists.

Johannes Kepler, the famous astronomer and mathematician, studied snowflakes in 1611 because he was intrigued by the hexagonal six-sided shape. Although he was smart enough to calculate orbits of several planets, he remained perplexed about how ice crystals formed. During the mid 1900s, water molecules were discovered to group together with six in a ring. Therefore, when this group of water molecules freeze in an ice crystal, a hexagonal shape results, presenting as a six-pointed star, six sided column or six sided plate. These hexagonal configurations allow air to be trapped between the crystal projections.

Scientists think no two snowflakes are perfectly the same, a difficult fact to accept considering how many snowflakes fall around the world every year. Every ice crystal starts on a speck of dust, ash, salt or bacteria on which water molecules aggregate then freeze, growing larger until the weight drops the crystal out of the cloud and to the ground.

During the next snowfall, collect a few snowflakes on a black paper or cloth. Inspect the tiny hexagonal ice crystals. You will discover astounding intricacy of star, column and plate shaped ice crystals.

Date Time Site Temperature Temperature difference

Feb 26 10:20 a.m. Porch post 10.8 17 degrees

4:12pm Snow bank 28.1

Feb 28 6:50 a.m. Porch post -13.5 40 degrees

9:10 a.m. Snow bank 26.5

Mar 5 5:35 p.m. Porch post 9.5 20 degrees

8:28 p.m. Snow bank 29.5

Mar 6 6:45 a.m. Porch post -3.4 33.1 degrees

5:41 a.m. Snow bank 29.7

Mar 10 4:38 p.m. Porch post 44.7 14.3 degrees

5:58 p.m. Snow bank 30.4