electrical properties of frozen ground
Link: http://w3id.org/permafrost/v/ipaglossary/t0096
Within: IPA Permafrost Glossary
Definition: The dielectric constant (or relative permittivity), electrical conductivity and electrical resistivity are the major electrical properties governing the flow of electric current through frozen ground.
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propriétés électriques du gélisol
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electrical properties of frozen ground en |
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The dielectric constant of a soil is a measure of the ability of the soil to store electrical energy in the presence of an electrostatic field; it is the ratio of the soil's permittivity to the permittivity of a vacuum. The electrical conductance of a soil is the inverse of the resistance offered by a soil to current flow. Current flow under an electrical gradient in a frozen soil occurs almost entirely through the unfrozen water films. Electrical conduction is related to the thickness of these water films and their degree of interconnection; it decreases with decreasing temperature and increases with increasing pressure. As a consequence, all these electrical properties are influenced by soil type, density, salinity, temperature and, in particular, the unfrozen water content. For example, the resistivity of unfrozen soils increases slightly with decrease in temperature. A significant increase in resistivity occurs when the soil freezes; this change is directly related to the decreasing unfrozen water content of the frozen ground. Available data show that the resistivities of frozen soils and rocks may be from 10 to more than 100 times larger than those of the same materials when unfrozen. Electromagnetic geophysical techniques for mapping permafrost, and the electrical grounding of various types of machines and electrical equipment, power transmission systems and radio transmitting antennae in permafrost areas, require a knowledge of the electrical properties of frozen ground.
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https://doi.org/10.4224/20386561
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