Snow and Avalanche Glossary


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Density

Also: Dense, Heavy, Low Density, Light

Density refers to Mass per volume, usually specified in kilogram per cubic meter (kg/m^3). The density of water is 1000 kg/m^3 and snow density is usually measured as a ratio to this. So snow which is 100 kg/m^3 is specified as 100/1000, or 10 percent (of the density of water).

The water content divided by the snow depth also gives the density of the snow. Example: 1.2" water equivalent divided by 15" of snow = .08 density (or 8 percent water content).

New snowfall is typically between 7% and 12% but can be lower or higher than this sometimes. Wind exposure often increases the density to 20% to 30%. Higher density (heavier) snow typically results from warmer temperatures and/or winds while lower density (lighter snow) usually results from colder air with less wind. The density will increase over time due to snow settlement. Old snow may reach 40% to 50% density and firn can reach 60%. The highest density of ice known is fully mature glacier ice.

When used qualitatively density is somewhat of a relative term. Dense snow usually refers to heavy snow that is not so much fun for skiing or snowboarding (but may be better for snowmobiling or snowshoeing). But Dense Powder means light powder snow which is just not as light (or low-density) as usual for the area.

The density of a layer of snow in a snowpit can be measured with a density cutter.

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This glossary is a work in progress and is made possible by AlpenPro.


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