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Atmospheric windows are useful for astronomy, remote sensing, telecommunications and other science and technology applications. In the study of the greenhouse effect, the term atmospheric window may be limited to mean the infrared window, which is the primary escape route for a fraction of the thermal radiation emitted near the surface. [4][5 ...
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.
Stefan surmised that 1/3 of the energy flux from the Sun is absorbed by the Earth's atmosphere, so he took for the correct Sun's energy flux a value 3/2 times greater than Soret's value, namely 29 × 3/2 = 43.5. Precise measurements of atmospheric absorption were not made until 1888 and 1904. The temperature Stefan obtained was a median value ...
The rays or waves may be diffracted, refracted, reflected, or absorbed by the atmosphere and obstructions with material and generally cannot travel over the horizon or behind obstacles. In contrast to line-of-sight propagation, at low frequency (below approximately 3 MHz ) due to diffraction , radio waves can travel as ground waves , which ...
Each higher-order mode is “born” at a resonant frequency of the plate, and exists only above that frequency. For example, in a 3 ⁄ 4 inch (19mm) thick steel plate at a frequency of 200 kHz, the first four Lamb wave modes are present, and at 300 kHz, the first six. The first few higher-order modes can be distinctly observed under favorable ...
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 ...
Note that different definitions of the molecular diameter, as well as different assumptions about the value of atmospheric pressure (100 vs 101.3 kPa) and room temperature (293.17 K vs 296.15 K or even 300 K) can lead to slightly different values of the mean free path.