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Glossary
A glossary of avalanche terms.
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- Anchors
- Trees, bushes or rocks protruding though the slab that may help hold it in place.Synonyms: anchor, anchors
- Aspect
- The compass direction a slope faces (i.e. North, South, East, or West.)Synonyms: aspect, aspects
- Avalanche Path
- A terrain feature where an avalanche occurs. Composed of a Starting Zone, Track, and Runout Zone.Synonyms: avalanche path
- Avalanche Transceiver
- An electronic device worn on the body to aide in quickly finding buried avalanche victims. Also called an avalanche beacon, it has the ability to send and receive a 457khz radio signal.Synonyms: avalanche tranceiver, Avalanche tranceiver
- Bed Surface
- The surface over which a fracture and subsequent avalanche release occurs. Can be either the ground or a snow surface.Synonyms: bed surface
- Collapse
- When the fracture of a lower snow layer causes an upper layer to fall. Also called a whumpf, this is an obvious sign of instability.Synonyms: Whumpf, whumpf, collapse
- Concave Slopes
- A terrain feature that is rounded inward like the inside of a bowl, i.e. goes from more steep to less steep.Synonyms: concave slopes, Concave slopes
- Considerable Danger
- Natural avalanches possible. Human triggered avalanches PROBABLE.Synonyms: CONSIDERABLE
- Convex Slopes
- A terrain feature that is curved or rounded like the exterior of a sphere or circle, i.e. goes from less steep to more steep. Convex slopes tend to be less safe than concave slopes. MenuSynonyms: convex slopes, Convex slopes
- Corn Snow
- Large-grained, rounded crystals formed from repeated melting and freezing of the snow.Synonyms: corn snow, Corn snow
- Cornice
- A mass of snow deposited by the wind, often overhanging, and usually near a sharp terrain break such as a ridge. Cornices can break off unexpectedly and should be approached with caution.Synonyms: cornice
- Couloir
- A steep gully in alpine terrain. In winter, a couloir is usually filled with snow bound by rocks on either side.Synonyms: couloir
- Cross Loading
- Wind blowing across a slope, depositing drifts on the sides of gullies or other terrain features.Synonyms: Cross Loaded, cross loading, Cross loading, cross loaded
- Crown Face
- The top fracture surface of a slab avalanche. Usually smooth, clean cut, and angled 90 degrees to the bed surface.Synonyms: crown face
- Danger Ratings
- In the U.S., a five-category estimation of the avalanche danger: Low, Moderate, Considerable, High and Extreme.Synonyms: danger ratings
- Deep Slab Avalanche
- Avalanches that break deeply into old weak layers of snow that formed some time ago.Synonyms: deep slab avalanche, deep slab avalanches, Deep slab avalanche
- Depth Hoar
- Large-grained, faceted, cup-shaped crystals near the ground. Depth hoar forms because of large temperature gradients within the snowpack.Synonyms: depth hoar, Depth hoar
- Dry Snow Avalanche
- An avalanche that occurs in snow below freezing temperatures.Synonyms: dry snow avalanche, Dry snow avalanche
- Extreme Danger
- Widespread natural or human triggered avalanches CERTAIN.Synonyms: EXTREME
- Faceted Snow
- Angular snow with poor bonding created from large temperature gradients within the snowpack.Synonyms: faceted snow, Faceted snow
- Fracture
- The physical separation of the slab from the bed surface and surrounding snow during the initiation of a slab avalanche.Synonyms: fracture
- Glide
- When the entire snowpack slowly moves as a unit on the ground, similar to a glacier.Synonyms: glide
- Graupel
- Heavily rimed new snow, often shaped like little Styrofoam balls. Synonyms: grappell, groppell, groppel, graupel
- Hard Slab Avalanche
- A slab avalanche of hard, dense snow.Synonyms: hard slab avalanche
- High Danger
- Natural and human triggered avalanches LIKELY.Synonyms: HIGH
- High Marking
- When a snowmobiler ascends a slope to the highest point they can reach. Also known as hill climbing.Synonyms: high marking
- Isothermal
- When all layers of the snowpack are at the same temperature, usually the freezing pointt. Often refers to a snowpack that is wet throughout its depth.Synonyms: isothermal
- Leeward
- The downwind side of an obstacle such as a ridge.Synonyms: leeward
- Loading
- The addition of weight on top of a snowpack, usually from precipitation, wind drifting, or a person.Synonyms: loading
- Loose Snow Avalanche
- An avalanche that releases from a point and spreads downhill collecting more snow - different from a slab avalanche. Also called a point-release or sluff.Synonyms: Point Release, Sluff, loose snow avalanche, Loose snow avalanche
- Low Avalanche Hazard
- Natural avalances very unlikely. Human triggered avalanches UNLIKELY.Synonyms: LOW
- Melt freeze snow
- Snow grains that have partially melted and then frozen again.Synonyms: melt-freeze snow, melt freeze snow
- Moderate danger
- Natural avalanches unlikely. Human triggered avalanches POSSIBLE.Synonyms: MODERATE
- Persistent weak layer
- Weak layers that continue to produce avalanches for several days or weeks after a storm.Synonyms: persistent weak layer, Persistent weak layer
- Probe
- A metal rod used to probe through avalanche debris for buried victims.Synonyms: probe
- Propagation
- The spreading of a fracture or crack within the snowpack.Synonyms: propagation
- Rain Crust
- A clear layer of ice formed when rain falls on the snow surface then freezes.Synonyms: rain crust
- Remote Trigger
- When the trigger point is outside of the boundary of the releasing slab.Synonyms: remote trigger
- Rime
- Supercooled water droplets that freeze to objects in exposed terrain, forming icy deposits on the windward side. Rime can also form on snowflakes as they fall through the sky, giving them a fuzzy appearence.Synonyms: rime
- Runout Zone
- The portion of an avalanche path where the debris typically comes to rest.Synonyms: runout zone
- Sastrugi
- Wind eroded snow, which often looks rough like frozen waves. Usually found on windward slopes.Synonyms: sastrugi
- Settlement
- The slow, deformation and densification of snow under the influence of gravity. Not to be confused with collaspingSynonyms: settlement
- Ski cut
- A stability test where a skier or rider rapidly crosses an avalanche starting zone to see if an avalanche initiates. Slope cuts can be dangerous and should only be performed by experienced people on small avalanche paths or test slopes.Synonyms: slope cut, ski cut
- Skin track
- Backcountry skiers and some snowboarders ascend slopes using climbing skins attached to the bottom of their skis.Synonyms: skinning, skin track
- Slab
- A relatively cohesive snowpack layer.Synonyms: slab
- Slide
- A mass of snow sliding, tumbling, or flowing down an inclined surface. Same as avalanche.Synonyms: slide
- Snow density
- Avalanches that break deeply into old weak layers of snow that formed some time ago.Synonyms: snow density
- Snow layer
- A snowpack stratum differentiated from others by weather, metamorphism, or other processes.Synonyms: snow layer
- Snow Metamorphism
- The physical change of snow grains within the snowpack due to differences in temperature and pressure.Synonyms: snow metamorphism
- Snowpit
- A pit dug vertically into the snowpack where snow layering is observed and stability tests may be performed. Also called a snow profile.Synonyms: snowpit
- Soft slab avalanche
- A slab avalanche of soft or low density snow.Synonyms: soft slab avalanche
- Stability
- The chance that an avalanche will not occur, relative to a given trigger (usually the weight of a human). Synonyms: stability
- Stability Test
- A procedure used to estimate the stability of the snowpack, often done in a snowpit. Common tests include the Rutschblock, compression or tap test, cornice drop, and slope cutSynonyms: stability test
- Starting Zone
- The portion of an avalanche path where an avalanche releases.Synonyms: starting zone
- Stepping down
- When a slab avalanche slides a short distance and breaks down into deeper weak layers forming a stair-step pattern on the bed surface.Synonyms: step down, stepping down
- Sun Crust
- A snow layer melted by radiation from the sun and subsequently refrozen.Synonyms: snu crust
- Surface Hoar
- Featherly crystals that form on the snow surface during clear and calm conditions - essentially frozen dew. Forms a persistent weak layer once buried.Synonyms: surface hoar
- Sympathetic Trigger
- When one avalanche triggers another avalanche some distance away.Synonyms: sympathetic trigger
- Temperature Gradient
- The change in temperature over snowpack depth.Synonyms: temperature gradient
- Terrain Trap
- Terrain in which the consequences of an avalanche are especially hazardous, such as a gully, an abrupt transition, an avalanche path that terminates in trees, a crevasse field or a cliff.Synonyms: terrain trap
- Track
- The portion of an avalanche path between the starting zone and the runout zone.Synonyms: track
- Trigger
- A disturbance that initiates fracture within the weak layer causing an avalanche. In 90 percent of avalanche accidents, the victim or someone in the victims party triggers the avalanche.Synonyms: trigger, triggered
- Trigger Point
- The area where a trigger initiates an avalanche.Synonyms: trigger point
- Upside-Down Storm
- When a snowstorm deposits denser snow over less dense snow, creating a slab/weak layer combination.Synonyms: upside down storm, upside-down storm
- Weak Interface
- A poor bond between two adjacent layers of snow.Synonyms: weak interface
- Weak Layer
- A snowpack layer with less strength than adjacent layers. Often the layer in the snowpack where an avalanche fractures.Synonyms: weak layer
- Wet Snow Avalanche
- An avalanche caused by snow losing its strength after becoming damp, moist or saturated with water.Synonyms: wet snow avalanche, Wet snow avalanche
- Wind Loading
- The added weight of wind drifted snow.Synonyms: wind loading, wind-loaded
- Wind Slab
- A cohesive layer of snow formed when wind deposits snow onto leeward terrain. Wind slabs are often smooth and rounded and sometimes sound hollow. Synonyms: wind slab, windslab
- Windward
- The upwind side of an obstacle such as a ridge. Usually snow is eroded from windward slopes making them relatively safer.Synonyms: windward
