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cylindrical irradiance (at a point, for a given direction of incidence) [Ee,z]

1. mean irradiance on the outer surface of a very small cylinder that is put vertically at a point in space, to obtain composite irradiance produced by incident radiation from various directions

2. equivalent definition: arithmetic mean of the vertical irradiance Ee,v at a point

        

where

Le is the radiance in the direction (ε,φ);

dΩ is the element of solid angle in direction (ε,φ));

ε is the angle of incidence measured with respect to the axis of the cylinder;

Ee,v is the vertical irradiance for an area element with its normal in the direction φ);

φ is the angle in the plane perpendicular to the axis of the cylinder

Unit: W·m-2

NOTE The analogous quantities "cylindrical illuminance", Ev,z, and "photon cylindrical irradiance", Ep,z, are defined in a similar way, replacing radiance, Le, by luminance, Lv, or photon radiance, Lp.

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