Internal Absorptance (of a homogeneous non-diffusing plate)
The ratio of the luminous flux absorbed between the entry and exit surfaces of the plate, to the flux which leaves the entry surface.
Symbol: ai ai + Ti = 1
Reference: C.I.E. (modified)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM