Difference between revisions of "Allard's Law"

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The law may be expressed as follows
The law may be expressed as follows


(Equation)
[[File:Allard1.gif]]


where E is the resulting illuminance on this surface
where E is the resulting illuminance on this surface
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Note: Another form of Allard's Law is
Note: Another form of Allard's Law is


(Equation)
[[File:Allard2.gif]]


where V = meteorological visibility (2-1-280 and 2-1-290, Note:).
where V = meteorological visibility (2-1-280 and 2-1-290, Note:).
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[[Category:Alphabetical Index]]
[[Category:Alphabetical Index]]
[[Category:IALA Dictionary 1970-89 Edition]]
[[Category:IALA Dictionary 1970-89 Edition]]
[[Category:Needs Editing]]

Revision as of 22:52, 25 October 2013

2-1-265

A formula relating the illuminance produced on a normal surface at a given distance from a point source of light, the intensity of the light and the degree of transparency of the atmosphere (assumed uniform).

The law may be expressed as follows

Allard1.gif

where E is the resulting illuminance on this surface

I is the intensity of the incident light in the direction of measurement.

T is the atmospheric transmission factor (assumed uniform) for specified Unit: distance.

x is the distance of the surface from the light source, measured in the specified units of distance.


Note: Another form of Allard's Law is

Allard2.gif

where V = meteorological visibility (2-1-280 and 2-1-290, Note:).




Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)