25 March, 2002
The Science Behind
Ice Thickness and Heat Flux
During my PE days in High School, I
recall my teacher lecturing us the importance of R and R (Rest and Recreation).
After a long
morning collecting data from four ponds, Dr. Jeffries and I decided
to lounge around the frozen pond side under the radiant sun. We've
got everything we need except sand; snow will just have to do!
Anyway, scroll down for the script.
1. Take I: March 25th, 11:47 am Within a week, ice thickness accumulated from 77.3 to 82.0 cm. Surface temperatures dropped from -0.1 to -3.2 C and snow depth decreased 1 cm. Snow density increased slightly as well. What do these measurements tell us?
2. Take II: March 25th, 12:04 am When ice accumulates, energy from latent heat of fusion or crystallization is released. As Dr. Jeffries would say, "When ice grows, heat flows."
3. Take III: March 25th, 12:15 pm A. Snow temperatures are measured for one part of the temperature gradient equation. During the winter in usual cases, the surface of the snow is colder than the base encouraging ice buildup. B. Snow depth is another measurement for temperature gradient. Snow cover is full of air molecules, providing excellent insulation. Recently, we've had a series of gust winds and now with longer daylight, snow cover has drastically changed. Loss of insulation means more ice accumulation. C. Snow density is a calculation of mass and volume. In dense snow, very little air molecules are present not providing good insulation. In this case, ice growth will continue.
4. Take IV: March 25th, 12:24 pm So, basically we have three factors that influence conductive heat flux: snow temperatures, depth, and density. This explains why ice accumulated almost 5 cm within a week.
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