Item: Granulation of Snow
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Title: Granulation of Snow
Proceedings: International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - October 07-11, 2013
Authors:
- Walter Steinkogler [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ CRYOS, School of Architecture, Civil and Environmental Engineering, EPFL, Lausanne, Switzerland ]
- Betty Sovilla [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Michael Lehning [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ CRYOS, School of Architecture, Civil and Environmental Engineering, EPFL, Lausanne, Switzerland ]
Date: 2013-10-07
Abstract: The mobility of an avalanche, i.e. its potential to move faster and further, can strongly differ for individual avalanches even if the release conditions are similar. Snow avalanches, as many geophysical flows, are often considered as granular flows. Studies on mono- and bidisperse materials in granular flow show a strong relation between mobility and the granular size distribution. Furthermore, the development of different flow regimes, e.g. whether a plug flow or a turbulent fluidized flow is formed, strongly depends on the granule properties in the avalanche. Therefore, the granular structures and size distributions in the deposition zone are often interpreted as indirect indicators for the internal flow dynamical characteristics of an avalanche. Our experiments show that granulation, the generic name for particle size enlargement, is substantially influenced by the properties of the snow before movement. We investigated granules and their properties in the deposition of multiple avalanches and used a concrete tumbler to examine the granulation potential of snow with different properties. Snow layers featuring similar properties were collected and a defined volume was inserted into the tumbler. The experiments showed that granules only formed when a snow temperature of -1°C was exceeded. The formed granules featured typical size distributions observed in avalanche deposits of real-scale avalanches. This confirms recent studies that the snow temperature plays a crucial role on granulation and consequently on the mobility of snow avalanches.
Object ID: ISSW13_paper_P2-58.pdf
Language of Article: English
Presenter(s): Unknown
Keywords: snow avalanche, granulation, snow temperature, mobility
Page Number(s): 766-769
Subjects: snow avalanche snow avalanche dynamics flow dynamics
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