|The International Classification for Seasonal Snow on the Ground|
Snow research is an interdisciplinary field, as reflected in variety of books dedicated to snow and its various aspects. Such a wide range of interest and knowledge in snow makes common descriptions of snow as well as common measurement practices very desirable. The classification deals primarily with seasonal snow, even though many concepts in the present snow classification can also be applied to firn, which is the first stage in the formation of glacier ice.
In 1948 the International Commission of Snow and Glaciers of the International Association of Scientific Hydrology, IASH, appointed a committee to report on the possibilities of standardizing an international snow classification system. This resulted in a publication in 1954, The International Classification for Snow with special reference to snow on the ground. Over time, knowledge about snow processes increased and observation practices differed increasingly from country to country. That is why in 1985 IAHS, the International Association of Hydrological Sciences, established a new committee on snow classification. Five years later, a fully revised and updated International Snow Classification of Seasonal Snow on the Ground was issued.
This work has been widely used as a standard for describing the most important features of seasonal snow on the ground and is often cited in publications where a common description is needed. The 1990 classification is also well accepted by practitioners world wide, providing the basic framework aimed at in 1954, namely:
To set up a classification as the basic framework which may be expanded or contracted to suit the needs of any particular group ranging from scientists to skiers. It has also to be arranged so that many of the observations may be made either with the aid of simple instruments or, alternatively, by visual methods. Since the two methods are basically parallel, measurements and visual observations may be combined in various ways to obtain the degree of precision required in any particular class of work.
Since 1990 our collective knowledge of snow and the techniques we use to observe its characteristics have evolved. Thus, in 2003, the current classification (Colbeck et al., 1990) needed an update.
The classification deals primarily with seasonal snow, even though many concepts in the present snow classification can also be applied to firn, which is the first stage in the formation of glacier ice. Definitions and tools are provided mainly to describe point observations of the snowpack, e.g., from snow pitwork.
Part 1 of the classification describes the fundamental characteristics of snow on the ground as well as a link to snow microstructure that is examined in Appendix B. Part 2 introduces additional features of snow as well as important measurements of the snow cover. Appendix A presents the grain shape classification, including photographic material. Basic guidelines for snow and snowpack observations are provided in Appendix C. The final three Appendices list the symbols used (D), define principal terms used in the text (E), and present a multilingual list of terms (F). A comprehensive but non-exhaustive bibliography completes the document.