Role Of Ice Research Articles

The Role of Debris-Rich Ice in Flow Near the Margins of Glaciers (Abstract)

The margins of many ice sheets and ice caps are marked by the presence of alternating layers of debris-laden and clean ice. The role of this ice in flow and sediment transport near the margins of glaciers has been the subject of considerable controversy between glacial geologists and glaciologists for over three decades. Glacial geologists (Goldthwait, 1951, 1960, 1971, 1975; Bishop, 1957; Souchez, 1967, Boulton, 1970, 1972; Hambrey, 1976) commonly refer to the debris-bearing ice bands as “thrust planes” or “shear planes”, apparently seeing them as reverse faults which transport rock debris from the glacier bed to the surface in a “conveyor-belt-like” manner (Goldthwait, 1975, p. 192). As supporting evidence for the shear-plane mechanism, glacial geologists have offered only qualitative observations and none seem to have actually observed it in action. Glaciologists on the other hand, particularly Weertman (1961), Hooke (1968; 1973), and Hooke and Hudleston (1978), have objected to this concept on physical grounds and have presented convincing arguments for doubting that it is mechanically sound. In spite of the controversy surrounding it, the shear-plane mechanism has gained wide acceptance among geologists and physical geographers and has been perpetuated in recent years through a number of popular introductory geology and physical geography textbooks (e.g. Embleton and King, 1975; Judson, Deffeyes, and Hargraves, 1976; Leet, Judson, and Kauffman, 1978; Press and Siever, 1982; Hamblin; 1982).

The role of ice and snow in lake heat budgets

Methods of precisely calculating the latent heat terms for snow and ice in the winter energy budget of lakes are presented. The ice term is normally overestimated and the snow term underestimated by existing methods.

The role of ice in the arctic beach environment with special reference to Cape Ricketts, southwest Devon island, Northwest Territories, Canada

The role of ice in the arctic beach environment with special reference to Cape Ricketts, southwest Devon island, Northwest Territories, Canada

Discussion

Dr A. T. J. D ollar said that this stimulating contribution to the geology of Scilly raised afresh controversial issues, particularly relating to gravels containing far-travelled erratics in, or associated with, the drift described, and to the likely role of ice in the transport and deposition of such constituents of this drift, which were investigated particularly by A. Smith (1858), G. Barrow (1906), C. W. Osman (1928) and by the speaker at intervals between 1954 and 1966. Regarding the extent of the elliptical submarine base of the two-granite pluton of Scilly, the speaker asked why the authors had adopted 30 square miles for this plane area rather than the value of nearly 50 square miles suggested by available bathymetric data. Further, in view of the elliptical plan of the pluton, what new evidence was there for regarding the mass as a boss, with its implication of a nearly circular cross-section, instead of the laccolite first proposed by C. W. Osman or the asymmetrical laccolithic form suggested by the speaker ( in D. L. Jones, Ph.D. Thesis, University of London, 1963), after a detailed structural study of the mass. In connexion with two large supposed inclusions of the former sedimentary envelope of the mass in the first granite, on White Island, St Martin’s, had the authors any views on the ambiguous field and laboratory evidence associated with this question, particularly in respect of the dyke-like schistose and tourmalinized body concerned ? In the two main granites, the authors had drawn attention to the

Monochromatic Polarization Measures of Comet Ikeya-Seki (1965f)

Monochromatic measures of polarization of Comet Ikeya-Seki (1965f) at 3 890 Å, 4 300 Å, 4 740 Å and 5 875 Å are described. The relative contributions of emission and continuum to radiation transmitted by the filters at 3 890 Å and 4 740 Å are evaluated. The polarization at phase angle 90° of the CN (0,0) band is 6.9% while that of the C 2 (1,0) band is 10.7%, in close agreement with the theoretical values for resonance fluorescence. The polarization value of the continuum is 24.7% at phase angle 90°, while for the same phase angle, a measure of the polarization in the tail, 3′ away from the head, is 13.6%. The agencies responsible for the continuum in both head and tail are likely to have a difference in the major constituent. The role of ices and iron particles as scattering agencies is discussed.

Comments on “What Is the Role of Ice in Summer Rain-showers?”

Comments on “What Is the Role of Ice in Summer Rain-showers?”

What is the Role of Ice in Summer Rain-Showers?

Abstract Recent observations indicate that ice pellets and snow pellets are present in most convective clouds in the Central United States by the time these clouds reach top temperatures of −10C. The attendant circumstances raise the question of whether the ice plays an active role in rain development in these clouds or whether its presence is purely incidental. The ice pellets are usually preceded by the development of liquid precipitation particles large enough to produce rain by coalescence with cloud droplets. The pellet concentrations are not related to ground-level ice nuclei concentrations. Apparently the pellets form as a result of freezing of the drops, contrary to most laboratory studies of droplet freezing. Observations can be brought into harmony by invoking the droplet splintering measurements of Mason and Maybank. The presence of numerous small ice particles in these clouds at temperatures warmer than −10C casts doubt upon the value of seeding with ice nuclei for rain inducement.