Thermo-Physical Characteristics of Glaciers — Toward a Rational Classification

• Published in: Journal of Glaciology
• Main Author: Miller, Maynard M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1976
• Subjects: Earth-Surface Processes; Arctic; Ahlmann; Lagally; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000031671; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000031671

Abstract Forty years ago, Ahlmann considered the thermo-physical character of ice masses as a basis for differentiating glaciers into two broad geophysical groups: (1) polar and (2) temperate . About the same time, Lagally sub-divided glaciers into corresponding thermodynamic categories: (1) kalt and (2) warmen . By this it was understood that the temperature of a polar, or “cold”, glacier was perennially sub-freezing throughout, except for a shallow surface zone which might be warmed for a few centimeters each year by seasonal atmospheric variations. Conversely, in a temperate, or “warm”, glacier, the temperature below a recurring winter chill layer was consistently at the pressure melting point. As these terms are thermodynamic in connotation, glaciers of the polar type may exist at relatively low altitudes if their elevations are sufficiently great. Temperate glaciers may be found even above the Arctic Circle at elevations low enough that chilling conditions are not induced by the lapse rate. In these distinctions, it is implied that regardless of geographical location a glacier’s mean internal temperature represents an identifiable characteristic which can be shown critically to affect the mass and liquid balance of ice masses and significantly to relate climatic influences to glacier regimes. The importance of these implications, and the fact that they are based on a gross, sometimes changing, and always difficult to measure, thermo-physical characteristic, makes some explicit terminology desirable. To some extent Ahlmann addressed this problem by introducing a subordinate classification, sub-polar glaciers. In these, the penetration of seasonal warmth involved only a shallow surface layer at 0°C, but still to a depth substantially greater than the superficial warming experienced in summer on polar glaciers. Lagally also recognized an intermediate type which he called “transitional”, characterized by a relatively deep penetration of 0°C englacial conditions during the summer. These pioneering efforts ...