Thermal and Physical Properties of Snow
during the Night Outcooling
Aleksey Isaev1
For the calculation of the snow parameters by the model of the snow cover it is necessary to know a
number of the thermal and physical properties of snow. The evaluation of quantities comprising the
equation of the common heat transfer in snow cover was made for the dry snow in the condition of
the night outcooling.
It was shown that the nighttime outcooling of the dry snow at any depth is to be provided with two
components: the ice skeleton conductive one and the thermal radiation. It is obvious that the integral
heat losses along the whole snow cover depth in this period are to be supplied with the conductive
heat exchange on the snowair interface and with the thermal radiation of the snow cover with the
subtraction of the value of the geothermal heat inflow from the soil.
The calculations based on the actual data of observations of the temperature regime of the snow
pack show that the inflow of the geothermal heat is much lesser than the heat losses in the snow
pack. The thermal radiation plays the major role in the nighttime outcooling. This is proved by the
fact that the snow cover surface is cooled during the nighttime more strongly than the surface air
layer.
The formula has been derived for the distribution of the snow temperature by the depth in the condi-
tions of the sudden nighttime outcooling. It was shown that the relationship between the thermal
conductivity of the dry snow and its density is presented in the same form as the temperature conduc-
tivity. The conclusion has been drawn about the possibility of the application of Fourie thermal
conductivity equation for the estimation of the coefficient of the dry snow thermal conductivity by
the data of 8 times thermogradient observations of the snow cover. The formula is presented for the
relationship between the temperature conductivity and the snow density by the observational data
obtained at Dukant station in the Western Tien Shan.
1 Central Asian Research Hydrometeorological Institute (SANIGMI), Republic of Uzbekistan, 700052, Tash-
kent, J. Makhsumov st., 72
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