Introduction

John C. King, John W. Pomeroy, Donald M. Gray, and Charles Fierz

Climates at the global, the regional, and the local scale determines the relative contributions of radiation, turbulent, and mass fluxes to the corresponding balance at the atmosphere-ground interface. In particular conditions, these fluxes induce the formation of a snowpack on the ground and predominantly effect its accumulation (depth), ablation (melt), sublimation, evaporation, as well as its structure (layering). Presence and transformation of the snow pack change the physical properties of the atmosphere-ground interface, which in turn affects the above fluxes, thereby influencing the properties of the lower atmosphere. For instance, the nearly black body emissivity of snow in the longwave range as well as surface temperature never exceeding 0 °C (273.15 K) promote an often persistent stable atmospheric boundary layer over the snowpack's surface, even in daytime. In addition, fluxes involved at the snow-atmosphere interface depend much on the ground vegetation, on the snowpack being continuous or patchy, as well as on topography.

These features, along with other particular physical properties of the snowpack such as its high albedo, its capability to store both frozen and liquid water and its low thermal conductivity lead to a strong feedback between the atmosphere and the snowpack, as well as to substantially altered climatic signals over seasonal snowpacks as compared with bare soil.

This chapter first presents general equations for both energy and mass balances (Section 3.2). Detailed discussions of each component of the energy balance follow (Section 3.3), including effects due to either vegetation or topography. Next, the influence of vegetation, blowing snow, as well as topography, on snow

Snow and Climate: Physical Processes, Surface Energy Exchange and Modeling, ed. Richard L. Armstrong and Eric Brun. Published by Cambridge University Press. © Cambridge University Press 2008.

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Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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