2023-08-29 07:33:20
Introduction
Airport Runway Visual Range Transmissometer
A transmissiometer is a visibility measuring instrument that records the attenuation of a beam of light (Light is all the electromagnetic waves visible to the eye…) passing through a fluid (A fluid is a material medium perfectly deformable. We group under this…) over a certain distance. The concentrated beam, generally emitted by a laser (A laser is a device that emits light (electromagnetic radiation)…), crosses (A cross is a fundamental element of the railway track. It is a piece placed across from…) the medium and is picked up at the end of the journey by a receiver whose angle (In geometry, the general notion of angle is declined in several concepts…) of vision is restricted to the direction of the source of the beam. The transmissiometers are mainly used in aeronautical meteorology (Aeronautical meteorology is the branch of meteorology dealing with…), but they find applications in other fields such as oceanography.
Principe
Visibility (In meteorology, visibility is the distance at which it is possible to…) is calculated using the coefficient (In mathematics a coefficient is a multiplicative factor that depends on a certain…) of extinction ( In general, the word extinction designates an action consisting in extinguishing some…) over the known distance separating the two instruments; coefficient depending on the length (The length of an object is the distance between its two extremities…) of wave (A wave is the propagation of a disturbance producing a variation in its path…) used. In general, transmissiometers measuring visibility in the atmosphere (The word atmosphere can have several meanings:) use a wavelength of regarding 550 nanometers, roughly in the middle of the visible spectrum (Visible light, also called visible spectrum or optical spectrum is the part of the spectrum…). We can find a series of transmissiometers, each pair (We say that a set E is a pair when it is formed of two distinct elements…) transmitter-receiver separated by 30 to 50 meters, along a track airport in order to capture variations in visibility along it.
The World Meteorological Organization considers that maximum visibility is the length of the path that a beam of parallel light rays, emanating from an incandescent lamp, must travel through the atmosphere at a temperature (Temperature is a physical quantity measured at using a thermometer and…) of color (The color is the subjective perception that the eye has of one or more wave frequencies…) of 2700 K, so that the intensity of the flux (The word flux (from the Latin fluxus, flow) generally designates a set of luminous elements…) is reduced to 0.05 times its original value; this is the meteorological optical range. A transmissiometer (A transmissiometer is an instrument for measuring visibility that records…) must have such sensitivity.
Types
Scatterometer, like the one added to the EMOR
The runway transmissiometer is placed in the axis of an airport runway (An airport is the set of buildings and installations of an aerodrome which…). The distance between the transmitter and the receiver can vary greatly depending on the generation of the instrument but is generally several tens of meters. It is used to estimate the visual range of the runway for aircraft pilots.
EMOR (Extended Meteorological Optical Range) transmissiometers are more recent. A scatterometer is placed on the same mast as the transmissometer transmitter. It measures the lateral scattering of light by the particles contained in the air; the latter being proportional to the visibility. Data (In information technology (IT), data is an elementary description, often…) independent of the two devices increases reliability (A system is reliable when the probability of fulfilling its mission over a period of.. .) measurement and serve (Servent is the contraction of the word server and client.) self-calibration. According to a manufacturer, the EMOR can be accurate up to 80 km even if the distance between the transmitter and the receiver of the transmissometer is only 30 meters.
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#Transmissiometer #Definition #Explanations
