Videos - Snow & avalanche science

Why does snow cool when melted with salt, and what does that have to do with avalanches?

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When salt is added to snow, the snow cools because heat from the snow flows into concentrated salt water around the salt grains. The surprisingly large amount of heat required for melting (i.e. latent heat) contributes to avalanche formation in at least two ways. Bruce Jamieson, 2020, CC BY-ND.

Case study of facets-on-crust in western Canada

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A case study for avalanche practitioners about a difficult winter in which a weak layer of facets on a melt-freeze crust produced avalanches - including many large hard-to-forecast avalanches - throughout the winter. Bruce Jamieson, 2019, CC BY-ND.

Solar induced dry slab avalanches

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A video for advanced recreationsts and avalanche practitioners about a poorly understood phenomenon that has surprised - sometimes tragically - many experienced people in the backcountry. Bruce Jamieson, Thomas Exner and Brad White, 2018, CC BY-ND.

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This video presents the technical concepts behind the current theory for the spontaneous release of dry slab avalanches. There are a few questions and answers at the end for keeners. Bruce Jamieson and Juerg Schweizer, 2016, CC BY-ND.

Crack propagation in human-triggered avalanches and snowpack tests

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For a skier, snowmobiler or other load to trigger a slab avalanche: the dynamic load must start a crack in a weak snowpack layer and then crack propagation must be sustained away from the load.
There is no one paper that summarizes the ideas in this video, but you could start by searching for "simenhois fracture propagation" and read the short 2009 article.
Bruce Jamieson, 2016, CC BY-ND.

The energy exchange at the snow surface

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An instructional video about the energy exchange at the snow surface and some of the persistent weak snowpack layers formed primarily by the energy exchange.

Bruce Jamieson, 2017, CC BY-ND.

Snow surface temperature on the sunny and shady sides of a roof

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Educational video for teaching about the radiation exchange on the sunny and shady sides of a snow covered roof. Shot in early November 2017 in Calgary, Canada. Updated April 2019.

The effect of incoming and outgoing radiation on the snow surface temperature of sunny and shady snowbanks

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Instructional video. Uses snow surface temperature to illustrate the effect of insolation (mostly incoming short-wave) and outgoing long wave radiation. The questions at the end assume the viewer has introductory knowledge of short and long wave radiation. Sounds starts with the questions. Shot in late October 2017 in Calgary, Canada.

Ductile and brittle fracture of toffee (and snow is like toffee)

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Simple illustrations of brittle and ductile fractures. Snow can fail and fracture in the same ways as toffee. Bruce Jamieson, 2016, CC BY-ND.

Are infrared images of the pit wall useful for avalanche forecasting? For avalanche education?

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A field experiment shows major limitations of IR images of the pit wall for avalanche forecasting. However, some images - including some free ones - are excellent for avalanche education. Bruce Jamieson and Mike Smith, 2018, CC BY-ND.

SWarm - Forecasting daytime warming of the upper snowpack

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This presentation explains the basics of daytime snowpack warming over terrain and introduces SWarm.
SWarm is a free spreadsheet that uses the maximum solar radiation to estimate daytime warming 10 cm below the surface over idealized terrain. You can select the date, latitude, expected cloud cover, and days since snowfall to see how these factors can influence the daytime snowpack warming down 10 cm.

For more on SWarm, see Laura Bakermans' paper at the 2008 ISSW in Whistler, BC.

Bruce Jamieson and Laura Bakermans, 2011, CC BY-ND.

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