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- Atmospheric_duct abstract "In telecommunication, an atmospheric duct is a horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals (and light rays) are guided or ducted, tend to follow the curvature of the Earth, and experience less attenuation in the ducts than they would if the ducts were not present. The duct acts as an atmospheric dielectric waveguide and limits the spread of the wavefront to only the horizontal dimension.Atmospheric ducting is a mode of propagation of electromagnetic radiation, usually in the lower layers of Earth’s atmosphere, where the waves are bent by atmospheric refraction. In over-the-horizon radar, ducting causes part of the radiated and target-reflection energy of a radar system to be guided over distances far greater than the normal radar range. It also causes long distance propagation of radio signals in bands that would normally be limited to line of sight.Normally radio "ground waves" propagate along the surface as creeping waves. That is, they are only diffracted around the curvature of the earth. This is one reason that early long distance radio communication used long wavelengths. The best known exception is that HF (3–30 MHz.) waves are reflected by the ionosphere.The reduced refractive index due to lower densities at the higher altitudes in the Earth's atmosphere bends the signals back toward the Earth. Signals in a higher refractive index layer, i.e., duct, tend to remain in that layer because of the reflection and refraction encountered at the boundary with a lower refractive index material. In some weather conditions, such as inversion layers, density changes so rapidly that waves are guided around the curvature of the earth at constant altitude. Phenomena of atmospheric optics related to atmospheric ducting include the green flash, Fata Morgana, superior mirage, mock mirage of astronomical objects and the Novaya Zemlya effect.".
- Atmospheric_duct thumbnail Superior_mirage_of_an_island.jpg?width=300.
- Atmospheric_duct wikiPageID "40732".
- Atmospheric_duct wikiPageLength "3222".
- Atmospheric_duct wikiPageOutDegree "36".
- Atmospheric_duct wikiPageRevisionID "644558642".
- Atmospheric_duct wikiPageWikiLink Atmosphere_of_Earth.
- Atmospheric_duct wikiPageWikiLink Attenuation.
- Atmospheric_duct wikiPageWikiLink Category:Atmosphere.
- Atmospheric_duct wikiPageWikiLink Category:Electromagnetic_radiation.
- Atmospheric_duct wikiPageWikiLink Category:Radio_frequency_propagation.
- Atmospheric_duct wikiPageWikiLink Creeping_wave.
- Atmospheric_duct wikiPageWikiLink Dielectric.
- Atmospheric_duct wikiPageWikiLink Diffraction.
- Atmospheric_duct wikiPageWikiLink Earth-Ionosphere_waveguide.
- Atmospheric_duct wikiPageWikiLink Earths_atmosphere.
- Atmospheric_duct wikiPageWikiLink Earth–ionosphere_waveguide.
- Atmospheric_duct wikiPageWikiLink Earth’s_atmosphere.
- Atmospheric_duct wikiPageWikiLink Electromagnetic_radiation.
- Atmospheric_duct wikiPageWikiLink Fata_Morgana_(mirage).
- Atmospheric_duct wikiPageWikiLink Green_flash.
- Atmospheric_duct wikiPageWikiLink Ground_wave.
- Atmospheric_duct wikiPageWikiLink Inversion_(meteorology).
- Atmospheric_duct wikiPageWikiLink Ionosphere.
- Atmospheric_duct wikiPageWikiLink Mirage.
- Atmospheric_duct wikiPageWikiLink Mirage_of_astronomical_objects.
- Atmospheric_duct wikiPageWikiLink Novaya_Zemlya_effect.
- Atmospheric_duct wikiPageWikiLink Over-the-horizon_radar.
- Atmospheric_duct wikiPageWikiLink Radio.
- Atmospheric_duct wikiPageWikiLink Radio_propagation.
- Atmospheric_duct wikiPageWikiLink Reflection_(physics).
- Atmospheric_duct wikiPageWikiLink Refraction.
- Atmospheric_duct wikiPageWikiLink Refractive_index.
- Atmospheric_duct wikiPageWikiLink Sky_wave.
- Atmospheric_duct wikiPageWikiLink Skywave.
- Atmospheric_duct wikiPageWikiLink Surface_wave.
- Atmospheric_duct wikiPageWikiLink Telecommunication.
- Atmospheric_duct wikiPageWikiLink Temperature_inversion.
- Atmospheric_duct wikiPageWikiLink Thermal_fade.
- Atmospheric_duct wikiPageWikiLink Tropospheric_ducting.
- Atmospheric_duct wikiPageWikiLink Tropospheric_propagation.
- Atmospheric_duct wikiPageWikiLink Wavefront.
- Atmospheric_duct wikiPageWikiLink Waveguide.
- Atmospheric_duct wikiPageWikiLink Weather.
- Atmospheric_duct wikiPageWikiLink File:Superior_mirage_of_an_island.jpg.
- Atmospheric_duct wikiPageWikiLinkText "Atmospheric duct".
- Atmospheric_duct wikiPageWikiLinkText "Ducting propagation between air layers in the lower atmosphere".
- Atmospheric_duct wikiPageWikiLinkText "atmospheric duct".
- Atmospheric_duct wikiPageWikiLinkText "duct".
- Atmospheric_duct wikiPageWikiLinkText "ducting effect".
- Atmospheric_duct wikiPageWikiLinkText "ducting".
- Atmospheric_duct wikiPageWikiLinkText "radar ducting".
- Atmospheric_duct hasPhotoCollection Atmospheric_duct.
- Atmospheric_duct wikiPageUsesTemplate Template:Reflist.
- Atmospheric_duct subject Category:Atmosphere.
- Atmospheric_duct subject Category:Electromagnetic_radiation.
- Atmospheric_duct subject Category:Radio_frequency_propagation.
- Atmospheric_duct hypernym Layer.
- Atmospheric_duct type AnatomicalStructure.
- Atmospheric_duct type Electrodynamic.
- Atmospheric_duct comment "In telecommunication, an atmospheric duct is a horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals (and light rays) are guided or ducted, tend to follow the curvature of the Earth, and experience less attenuation in the ducts than they would if the ducts were not present.".
- Atmospheric_duct label "Atmospheric duct".
- Atmospheric_duct sameAs Dukting.
- Atmospheric_duct sameAs m.0b4qr.
- Atmospheric_duct sameAs Q4817109.
- Atmospheric_duct sameAs Q4817109.
- Atmospheric_duct wasDerivedFrom Atmospheric_duct?oldid=644558642.
- Atmospheric_duct depiction Superior_mirage_of_an_island.jpg.
- Atmospheric_duct isPrimaryTopicOf Atmospheric_duct.