Chapter 2 - Physical, thermal, and mechanical properties of snow, ice, and permafrost

Abstract

The physical, thermal, and mechanical properties of snow, ice, and permafrost are responsible for the response of these cryospheric materials to external stressors. An understanding of these properties is therefore also key to evaluating associated cryospheric hazards. The material properties of snow, ice, and permafrost vary over many orders of magnitude. Generally, ice has the smallest range in physical and thermal properties (e.g., density or thermal conductivity), while properties of snow and frozen ground have much larger variations. The frozen ground has the largest absolute range in thermal properties (e.g., thermal conductivity: 0.1–4.0W/m/K), and snow has the largest relative range in physical properties (e.g., thermal conductivity: 0.04–1.0W/m/K). The mechanical response of each material, including its strength response and creep behavior, also varies widely, depending on stress, temperature, and loading rate. Rapid loading or cold conditions result in brittle behavior with high peak strength and small critical strain, while slow loading or warm conditions result in ductile behavior with low peak strength and large strain. An assessment of hazards associated with snow, ice, and permafrost requires an appreciation of how the basic properties of these cryospheric materials are influenced and changed by environmental conditions.