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Attenuation. In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable attenuation rates. Hearing protectors help reduce acoustic flux from flowing into the ears ...
The infrared atmospheric window is an atmospheric window in the infrared spectrum where there is relatively little absorption of terrestrial thermal radiation by atmospheric gases. [ 1 ] The window plays an important role in the atmospheric greenhouse effect by maintaining the balance between incoming solar radiation and outgoing IR to space.
Soil gases (soil atmosphere[ 1 ]) are the gases found in the air space between soil components. The spaces between the solid soil particles, if they do not contain water, are filled with air. The primary soil gases are nitrogen, carbon dioxide and oxygen. [ 2 ] Oxygen is critical because it allows for respiration of both plant roots and soil ...
The mass attenuation coefficient can be looked up or calculated for any material and energy combination using the National Institute of Standards and Technology (NIST) databases. [ 7 ] [ 8 ] In X-ray radiography the calculation of the mean free path is more complicated, because photons are not mono-energetic, but have some distribution of ...
In acoustics, acoustic attenuation is a measure of the energy loss of sound propagation through an acoustic transmission medium. Most media have viscosity and are therefore not ideal media. When sound propagates in such media, there is always thermal consumption of energy caused by viscosity. This effect can be quantified through the Stokes's ...
Infiltration (hydrology) Cross-section of a hillslope depicting the vadose zone, capillary fringe, water table, and phreatic or saturated zone. (Source: United States Geological Survey.) Infiltration is the process by which water on the ground surface enters the soil. It is commonly used in both hydrology and soil sciences.
The normalized difference vegetation index (NDVI) is a widely-used metric for quantifying the health and density of vegetation using sensor data. It is calculated from spectrometric data at two specific bands: red and near-infrared. The spectrometric data is usually sourced from remote sensors, such as satellites.
Solar irradiance spectrum at top of atmosphere, on a linear scale and plotted against wavenumber. The solar constant (G SC) measures the amount of energy received by a given area one astronomical unit away from the Sun. More specifically, it is a flux density measuring mean solar electromagnetic radiation (total solar irradiance) per unit area.