ATMOSPHERIC DUCT Meaning and
Definition
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An atmospheric duct refers to a phenomenon in the field of meteorology and atmospheric science. It entails a horizontal path or channel through which electromagnetic waves, particularly radio waves, can travel over long distances with remarkably little attenuation or dispersion. This effect occurs due to the bending and trapping of these waves within a region of the Earth's atmosphere, resulting in them being guided along a specific path.
Atmospheric ducts can arise when there is a significant variation in the refractive index of the air as a function of altitude, such as when there are contrasting temperature and humidity layers. These variations cause the waves to undergo refraction, allowing them to travel over a much greater distance compared to their line-of-sight path. This phenomenon is particularly prevalent in situations where the temperature decreases with altitude (known as a temperature inversion), leading to a bending effect that keeps the waves closer to the Earth's surface and aids their propagation.
Atmospheric ducts have practical implications, notably in radio communication and telecommunications. They can enhance the range and coverage of radio transmissions, enabling signals to be received from distant locations that would otherwise be out of range. However, they can also introduce distortions and interference due to the bending and dispersion of the waves, leading to signal degradation and reduced clarity. Understanding and characterizing atmospheric ducts are crucial in various fields, particularly for the purpose of improving signal transmission and reception in the absence of physical obstructions.
Etymology of ATMOSPHERIC DUCT
The term "atmospheric duct" is composed of two words: "atmospheric" and "duct".
The word "atmospheric" comes from the Greek word "atmos" meaning "vapor" or "air" and the Greek word "sphaira" meaning "sphere". It was originally used to refer to the envelope of gases surrounding the Earth or any celestial body. The term was later expanded to include the Earth's atmosphere, which is the layer of gases surrounding the planet that extends up to several hundred kilometers.
The word "duct" comes from the Latin word "ductus", which means "a leading" or "a means of conveyance". In the context of atmospheric ducts, it refers to a channel or passage through which atmospheric conditions, such as temperature and humidity, permit the propagation of certain types of waves or signals, particularly in the field of radio communication.
