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Area Lighting / Visual signalling

IEV ref845-11-27

en
Allard's law
law relating the illuminance E produced on a surface by a light source to the luminous intensity I of the source in the direction to the surface, to the distance d between the surface and the source, and to the atmospheric transmissivity T, which is assumed to be uniform; the surface is normal to the direction of the source and sufficiently distant for the source to be considered as a point source

E= I d 2 T d/ d 0 MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaadweacqGH9aqpdaWcaaqaaiaadMeaaeaacaWGKbWaaWbaaSqabeaacaaIYaaaaaaakiabgwSixlaadsfadaahaaWcbeqaamaalyaabaGaamizaaqaaiaadsgadaWgaaadbaGaaGimaaqabaaaaaaaaaa@3FF9@

where d0 is the length specified in the definition of T

Note 1 – The above formula is sometimes written

E= I d 2 T d MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaadweacqGH9aqpdaWcaaqaaiaadMeaaeaacaWGKbWaaWbaaSqabeaacaaIYaaaaaaakiabgwSixlaadsfadaahaaWcbeqaaiaabsgaaaaaaa@3E11@

where the exponent d in Td is the numerical value of the distance d measured with d0 as "unit".

Note 2 – Taking into account the relationship given in 845-11-20 between T and the meteorological optical range ν, this law can also be written as

E= I d 2 0,05 d/v MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGe aGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaq Fn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpe WZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaadweacqGH9aqpda WcaaqaaiaadMeaaeaacaWGKbWaaWbaaSqabeaacaaIYaaaaaaakiab gwSixlaaicdacaGGUaGaaGimaiaaiwdadaahaaWcbeqaamaalyaaba GaamizaaqaaiaadAhaaaaaaaaa@4132@


fr
loi d'Allard, f
loi donnant l'éclairement lumineux E produit sur une surface par une source lumineuse en fonction de l'intensité lumineuse I de la source dans la direction de la surface, de la distance d entre la surface et la source et de la transmissivité atmosphérique T que l'on suppose uniforme; la surface est normale à la direction de la source et celle-ci est suffisamment éloignée pour qu'on puisse la considérer comme une source ponctuelle

E= I d 2 T d/ d 0 MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaadweacqGH9aqpdaWcaaqaaiaadMeaaeaacaWGKbWaaWbaaSqabeaacaaIYaaaaaaakiabgwSixlaadsfadaahaaWcbeqaamaalyaabaGaamizaaqaaiaadsgadaWgaaadbaGaaGimaaqabaaaaaaaaaa@3FF9@

d0 est la longueur spéсifiéе pour la définition de E

Note 1 – La formule ci-dessus est parfois écrite sous la forme

E= I d 2 T d MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaadweacqGH9aqpdaWcaaqaaiaadMeaaeaacaWGKbWaaWbaaSqabeaacaaIYaaaaaaakiabgwSixlaadsfadaahaaWcbeqaaiaabsgaaaaaaa@3E11@

où l'exposant d dans Td est la valeur numérique de la distance d mesurée avec d0 comme "unité".

Note 2 – Tenant compte de la relation donnée à 845-11-20 entre T et la portée optique météorologique ν, cette loi peut aussi s'écrire

E= I d 2 0,05 d/v MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGe aGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaq Fn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpe WZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaadweacqGH9aqpda WcaaqaaiaadMeaaeaacaWGKbWaaWbaaSqabeaacaaIYaaaaaaakiab gwSixlaaicdacaGGUaGaaGimaiaaiwdadaahaaWcbeqaamaalyaaba GaamizaaqaaiaadAhaaaaaaaaa@4132@


ar
قانون الارد للاستضاءة

de
Gesetz von Allard, n

es
ley de Allard

fi
Allardin laki

it
legge di Allard

ko
알라드 법칙

ja
アラードの法則

no
nb Allards lov

nn Allards lov

pl
prawo Allarda

pt
lei de Allard

sv
Allards lag

Publication date: 1987
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