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Area Lighting / Visual signalling

IEV ref 845-31-018

Symbol
v

en
meteorological optical range
length of the path in the atmosphere that is required to attenuate by 95 % the luminous flux in a collimated beam from a source at a colour temperature of 2 700 K

Note 1 to entry: The value of the attenuation has been chosen so that the meteorological optical range provides an approximate measure of the commonly used concept of meteorological visibility.

Note 2 to entry: The meteorological optical range, v, is related to the atmospheric transmissivity, T, assumed to be uniform, by the formula

v= d 0 log0,05 logT MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadAhacqGH9aqpcaWGKbWaaSbaaSqaaiaaicdaaeqaaOWaaSaaaeaa jaaqciGGSbGaai4BaiaacEgakiaaykW7caaMc8EcaaKaaGimaiaacY cacaaIWaGaaGynaaGcbaqcaaKaciiBaiaac+gacaGGNbGccaaMc8Ua aGPaVlaadsfaaaaaaa@4B84@ or T= 0,05 d 0 /v MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadsfacqGH9aqpjaaqcaaIWaGaaiilaiaaicdacaaI1aGcdaahaaWc beqaaiaadsgadaWgaaadbaGaaeimaaqabaWccaGGVaGaamODaaaaaa a@3FDD@

where d0 is the length specified in the definition of atmospheric transmissivity.

These formulae are sometimes written

v= log0,05 logT MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadAhacqGH9aqpdaWcaaqaaKaaajGacYgacaGGVbGaai4zaOGaaGPa VlaaykW7jaaqcaaIWaGaaiilaiaaicdacaaI1aaakeaajaaqciGGSb Gaai4BaiaacEgakiaaykW7caaMc8Uaamivaaaaaaa@49AB@ or T= 0,05 1/v MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadsfacqGH9aqpjaaqcaaIWaGaaiilaiaaicdacaaI1aGcdaahaaWc beqaaiaaigdacaGGVaGaamODaaaaaaa@3EC4@

with d0 set to unity.

Note 3 to entry: This entry was numbered 845-11-20 in IEC 60050-845:1987.


fr
portée optique météorologique, f
longueur d'un trajet dans l'atmosphère nécessaire pour réduire de 95 % le flux lumineux d'un faisceau collimaté, émanant d'une source de température de couleur 2 700 K

Note 1 à l'article: La valeur de la réduction de telle sorte que la portée optique météorologique conduise à une mesure approximative de la notion couramment employée de visibilité météorologique.

Note 2 à l'article: La portée optique météorologique v est reliée à la transmissivité atmosphérique T, réputée uniforme par les formules

v= d 0 log0,05 logT MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadAhacqGH9aqpcaWGKbWaaSbaaSqaaiaaicdaaeqaaOWaaSaaaeaa jaaqciGGSbGaai4BaiaacEgakiaaykW7caaMc8EcaaKaaGimaiaacY cacaaIWaGaaGynaaGcbaqcaaKaciiBaiaac+gacaGGNbGccaaMc8Ua aGPaVlaadsfaaaaaaa@4B84@ ou T= 0,05 d 0 /v MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadsfacqGH9aqpjaaqcaaIWaGaaiilaiaaicdacaaI1aGcdaahaaWc beqaaiaadsgadaWgaaadbaGaaeimaaqabaWccaGGVaGaamODaaaaaa a@3FDD@

d0 est la longueur spécifiée dans la définition de la transmissivité atmosphérique.

Ces formules sont parfois écrites sous la forme

v= log0,05 logT MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadAhacqGH9aqpdaWcaaqaaKaaajGacYgacaGGVbGaai4zaOGaaGPa VlaaykW7jaaqcaaIWaGaaiilaiaaicdacaaI1aaakeaajaaqciGGSb Gaai4BaiaacEgakiaaykW7caaMc8Uaamivaaaaaaa@49AB@ ou T= 0,05 1/v MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadsfacqGH9aqpjaaqcaaIWaGaaiilaiaaicdacaaI1aGcdaahaaWc beqaaiaaigdacaGGVaGaamODaaaaaaa@3EC4@

avec d0 définie comme unité.

Note 3 à l'article: Cet article était numéroté 845-11-20 dans l'IEC 60050-845:1987.


ar
المدى البصرى للرصد الجوى

cs
meteorologická dohlednost

de
meteorologisch optische Sichtweite, f

it
portata ottica meteorologica

ko
기상학적광학거리계

ja
気象光学距離

nl
nl meteorologisch dagzicht

nl
be meteorologisch optisch bereik, n

pl
zasięg meteorologiczny optyczny, m

pt
alcance óptico meteorológico

zh
气象光学范围

Publication date: 2020-12
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