Radiation exchange determines the thermal regime of a snow cover.

Thermal conduction in snow is limited by the amount contact between ice particles. A newly fallen dry snow offers less of contact between ice particles and hence is an efficient insolating material. In contrast, a dense and wet spring-snow is an efficient T-conductor.

Formula 1. :

Heat flux through snow q = k x dT/dx

 q [W/m²]
 k [W/(m°K)] thermal conductivity coefficient
 T [°K] Temperature in Kelvin
 x [m] distance over which heat flow is calculated

The thermal conductivity coefficient k increases markedly with increasing snow density, as the number of ice particles in contact increases per volume of snow.

Here you see the soil surface temperature graphs from two neighbouring locations. Observe the temperature differences and decide which graph shows the conditions on the location with the thicker snow cover.

Help?

1 - Development of the soil surface temperature of an alpine meadow near Nendaz (2125m), Switzerland, and of an alpine meadow sparsely covered with snow near Zermatt (2300m) between November 1 1999 and May 29 2001, Switzerland

2 - Example of the snow cover in a wind-rich area with low snow depth. (128K)

29 August 2011
© ALPECOLe 2002-2007