When life gives you lemons, make lemonade, when life gives you lotsa snow, go out and collect data. And that's exactly what I did last night following the massive snow storm we had. Once again, I measured the temperature under the snow, specifically repeating the measurements reported in this post.
Here was the set-up:
The yellow thermometer was a waterproof thermistor the probe of which was pushed to a depth of 60 cm below the surface of the snow to a point right above the top of the soil. The other one was also a thermistor for the measurement of air temperature right above the snow surface. Because the latter is not waterproof, I had to protect it by placing it into a plastic bag, leaving only the probe out. The Lean Cuisine pepperoni pizza box was functioning as a snow shield (it was still snowing when I started the experiment), while the cardboard tube covered with aluminum foil around the probe was functioning as a radiation shield (or so I hoped).
And here are the results:
Even though the air temperature dropped more than 10 °C, the temperature 60 cm below the surface of the snow was stable throughout the night. Once again, these data show how well an insulator snow is.
The observed insulation is probably due to the tiny air pockets trapped between the snow crystals. Since the soil temperature is normally higher that the air temperature, the measured temperature right above the soil surface remains higher than the air temperature above the snow.
Part 2 in this series presented temperature data as a function of depth below the snow.