What Is a Snow Load?

Snow cover, also known as snow cover or snow cover, refers to the snow layer covering the land and sea ice surface. The area covered by snow on the ground reaches more than half of the visible area around a ground, which is called snow accumulation.

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retention of snow; perpetual snow; snow mantle; snow coverage ^[1]

1. Snow piles up; snow piles up.

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1. Climate change indicator. Snow cover is very sensitive to temperature changes, and climate change at any time and space scale is accompanied by snow cover fluctuations of different scales. CO2 and other greenhouse gases in the atmosphere continue to increase, leading to climate warming, reduced snow coverage, and the melting of permanent snow margins and sea level rise. Conversely, the snow area will expand and even cause glaciers to advance or expand. The interannual fluctuations of seasonal snow cover are related to the El Niño-Southern Oscillation, which is the result of anomalous global air-sea relations and temperature changes caused by volcanic eruptions.

2. Climate feedback. The fresh snow can reflect 85-95% of the short-wave radiation of the sun, and only the infrared part is absorbed by the surface layer. The thermal emissivity is 0.98-0.99, which is almost close to completely black body. Therefore, snow can form a cold-source underlying surface and a near-temperature inversion stratification, which can reduce the near-surface temperature by several degrees (° C). Significant differences in thermal conditions between snow-covered and non-snow-covered areas have enhanced mid-latitude cyclone activity. Anomalous snow can cause the cyclone path to shift. Fluctuations in snow cover in Eurasia affect East Asian atmospheric circulation, Indian monsoon activity, and early summer precipitation in China. Changes in snow cover also cause a reflectivity-temperature feedback cycle: if snow cover increases, the surface reflectance increases, the amount of absorbed solar energy decreases, the temperature decreases, and the snowfall increases; otherwise, the temperature increases and the snowfall decreases.

3. An important source of fresh water. The annual freshwater replenishment from snowfall on the land is about 60,000 × 10 cubic meters, which accounts for about 5% of the annual freshwater replenishment on land. The northern and mountainous rivers of the three continents of Asia, Europe, and North America are mainly replenished by seasonal snowmelt. For example, three-fourths of the rivers in the Soviet Union accounted for more than 50% of the total runoff recharge. The amount of winter snow reserves also determines the water use plan of the river basin and the scale of spring floods. Agricultural irrigation in the Andes of South America and the arid regions of central Asia relies on melting snow and ice in high mountains. China's annual average snow supply is 3451.8 × 10 ⁸ cubic meters, and half of the snow resources are concentrated in the western and northern high mountains.

4. Insulation and water storage effect on soil. Snow has very poor thermal conductivity, with an effective thermal conductivity of only 0.00063 to 0.00167 Joules / cm, which is a good thermal insulation layer on the ground. Even if the temperature is much lower than the freezing point, the snow layer with a thickness of 30-50 cm can prevent the covered soil from being frozen and create good wintering conditions for the crops. And the evaporation on the snow surface is very small, almost close to zero, so it has a very significant effect on soil water retention and spring drought prevention.

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