Rain-on-snow events can cause wet snow avalanches. Laboratory experiments were carried out to investigate the change in snow strength with increasing water content through rainwater percolation. Snowpack was artificially prepared consisting of a thin ice layer and fine compacted snow, and rainfall (2mmh–1) was artificially applied 22–25.5 and 49–52 hours after the snowpack was formed. Snow hardness was measured with a push–pull force gauge to indicate the snow strength before and after each rain-on-snow event. After the first rainfall, the upper half of the snowpack became wet and a rapid decrease in snow hardness was observed. After the second rainfall the rainwater penetrated the ice layer, high water content was observed above the ice layer but the hardness exceeded that estimated from an empirical relationship between hardness and water content. Micrographs of the snow particles suggest that the delay in grain coarsening observed near the wetting front induces the harder than estimated snow condition.

The water retention curve (WRC), which shows the relationship between the volumetric liquid water content, θv, and suction, h, is a fundamental part of the characterization of hydraulic properties. Therefore, the formulation of the WRC as a function of snow characteristics is essential for establishing a model of water movement through the snow cover. In this study, we measured the WRC of several snow samples, which had different characteristics (grain size, bulk dry density and grain type), using a gravity drainage column experiment and then analysed these data using the Van Genuchten soil physics model (VG model). The shape of the WRC depended strongly on both the sample grain size, d, and bulk dry density, ρ. Therefore, we introduced the parameter ρ/d to model the WRC of snow. The relationships between the parameters α and n of the VG model and ρ/d change with grain type. For melt forms, α, which is related to the inverse value of the air-entry suction, increases quickly as ρ/d decreases, whereas n, which is related to the gradient of θv vs h, increases with ρ/d. Conversely, neither of these parameters of the VG model for rounded grains showed obvious dependence on ρ/d. These results suggest that water movement through snow cover can be modelled using grain size, bulk dry density and grain type based on the soil physics model.

This paper considers the possible commercial viability of applying the moving particle semi-implicit (MPS) method to avalanches. The MPS method is a powerful tool for reproducing the flow phenomenon with large-scale surface deformation. In order to apply this method to snow avalanches, we modified the original model to introduce constitutive equations of Bingham fluid, dilatant fluid and the erosion–deposition process. The modified model was applied to some cases and evaluated through comparison with experimental results and observed data.

The results of snow-cover chemical composition research in Lefortovo District, Moscow, Russia, are considered. The technogenic impact on snow-cover contamination was evaluated using snow sampling, chemical analysis of liquid and solid phases of snow and data processing. Snow meltwaters were slightly acidic, low-mineralized and contaminated with oil products. Contrasting anomalies of chloride, sodium, nitrites, nitrates, oil products and 3,4-benzopyrene are revealed and the main causes of their formation analyzed. The technogenic load on the air and snow cover was mainly due to an extensive road network and the impact of industrial enterprise. Ecogeochemical associations of elements, polluting snow cover by means of the dust component of air, formed the specific types of geochemical zones due to industrial and road-transport emissions. The common type of man-made contamination in snow cover is characterized by the following general association of contaminants: Hg W Mo Cr Ni Co Pb Cu Zn Cd Ag Bi Sn Ba Nb.

The results of monitoring the rate of recrystallization of snow cover at sites with different degrees of humidity are presented. Observations were carried out at two sites within the same stratigraphic complex of snow cover in the south of Sakhalin island, Sea of Okhotsk. The basic structural changes in snowpack were traced. We determined the rate of growth of the diameter of the crystals in the snow layer. The structure of the snowpack was studied using E.G. Kolomyts’s technique. On the basis of stratigraphic observations, diagrams of the stratification of the snow cover were created, to determine the rate of evolution of ice crystals in a separate layer from its inception.

An experiment using artificial snow was conducted to clarify the influences of temperature and normal load on temporal variations in the shear strength of snow. Artificial snow consisting of dendritic crystals was allowed to accumulate to ∼60 cm depth for the experiment. The shear strength, temperature and weight of the overlying snow were measured at three different depths in the accumulated snow. For the measurement of shear strength, the shear frame index (SFI) was found using a shear frame by placing weights with different masses on the snow contained within the frame. The measured SFI values were treated with the Mohr–Coulomb failure criterion to find the snow cohesion factor C and the internal friction factor tanϕ. The results highlighted similar trends for SFI and C values by which their rate of increase over time was greater with higher snow temperatures and normal load caused by overlying snow. This indicates that C contributes significantly to increased SFI values. tanϕ decreased over time with higher snow temperatures and increased with lower snow temperatures. In low-temperature conditions, in particular, it is likely that snow crystals are compacted but maintain their dendritic morphology.

Snowpacks can be described as monogenetic rock, where ice is the basic mineral. They can thus be described in terms of a lithologic complex, that is a cluster of different rocks related by formation process or geological era. The stratigraphic complex of snow cover can be cast as a lithologic complex formed in a certain landscape, passing through stages of sedimentation and diagenesis in similar conditions and forming in the same winter a similar spectrum of stratigraphic columns. The stratigraphic complex possesses similar stratification, structure and texture alongside physical, chemical and mechanical characteristics. In landscapes of the same type located in different regions, the same type of stratigraphic complex is formed. The structural transformation of the snowpack is quantitatively described by coefficients of snowpack recrystallization, secondary stratification and texture. Landscape-indicative properties of snowpacks allow the construction of a unified taxonomic scale of stratigraphic complex with a hierarchy of levels: class, subclass, type, subtype and kind.

Snow cover contains various impurities from natural and anthropogenic sources. These impurities percolate into the soil, groundwater and surface water during snowmelt, significantly influencing their composition. We consider the metals content in snow cover in south Sakhalin, Sea of Okhotsk. Samples were taken in February–April 2011 by the Laboratory of Avalanche and Debris-flow Processes of the Sakhalin Department of the FEGI FEB RAS. Sample analysis was performed by the Laboratory of Analytical Chemistry, FEGI FEB RAS. Overall, the metals present in the highest concentrations were Ca, K, Mg and Na. Other metals have low concentrations at the level of total mineralization of surface water and groundwater. Thus, the main sources of metals in south Sakhalin snow cover are the water surface of the sea and anthropogenic sources.

Dry-snow metamorphism was the focus of extensive investigations in Russia over several decades. Large amounts of data were collected and used to construct a conceptual model based on crystallographic laws. The difference in terminology compared with the conventional model made these results less accessible to the wider international snow science community. This paper attempts to explain this terminology and its background so that the reported findings are not overlooked in ongoing investigations of the driving forces and consequences of snow metamorphism.

We contrast the frontal dynamics of dilute powder snow avalanches with the behavior of their tail. While the former can be regarded as a fast-moving eruption current dominated by synergistic material injection into a short head, the latter behaves as a nearly arrested dilute cloud of particles expanding by progressive incorporation of ambient air, or by entrainment of snow-cover material by late avalanches trailing well behind the front.