# 17-21-055

Ee,c; Ec

mean value of irradiance on the outer curved surface of a very small (real or imaginary) cylinder that is oriented vertically at a point in space

Note 1 to entry: Cylindrical irradiance is sometimes also defined as arithmetic mean of the vertical irradiance Ee,v at a point

where Ee,v is the vertical irradiance for an area element with its normal in the direction φ, and φ is the angle in the plane perpendicular to the axis of the cylinder.

Note 2 to entry: The corresponding photometric quantity is "cylindrical illuminance". The corresponding quantity for photons is "photon cylindrical irradiance".

Note 3 to entry: The cylindrical irradiance is expressed in watt per square metre (W·m−2).

Note 4 to entry: This entry was numbered 845-01-41 in IEC 60050-845:1987.

Note 5 to entry: This entry was numbered 17-274 in CIE S 017:2011.

Publication date: 2020-12