Effects of temperature and impurities on the dc conductivity of snow

Several major parameters affecting the electrical behavior of natural snow, namely volume conductivity and density, liquid water content and conductivity of water melted from snow, are crucial for the characterization of the electrical performance of snow-covered HV insulators. However, little study has been devoted to this subject, despite of its importance. These parameters are found to vary significantly with snow composition and purity as well as with other parameters, such as temperature, airborne pollutants, electric field strength and polarity. From laboratory experiments carried out on a large number of snow samples, it was found that dc conductivity of snow shows a peak at about -2[degrees]C. This apparently curious behavior near the melting temperature is attributed to important changes to the microstructure of snow. A correlation between dc conductivity and snow temperature was established. Index Terms--snow, conductivity measurement, density, heating, cooling, insulation.