Editing Transmittance (section)

===Hemispherical transmittance===
'''Hemispherical transmittance''' of a surface, denoted ''T'', is defined as<ref name="ISO_9288-1989">{{cite web |date=August 1, 2022 |year= |title=Thermal insulation — Heat transfer by radiation — Vocabulary |url=http://www.iso.org/iso/homehttps://www.iso.org/standard/82088.html/store/catalogue_tc/catalogue_detail.htm?csnumber=16943 |access-date=February 12, 2025 |work=ISO 9288:2022 |publisher=[[International Organization for Standardization|ISO]] catalogue}}</ref>
:<math>T = \frac{\Phi_\mathrm{e}^\mathrm{t}}{\Phi_\mathrm{e}^\mathrm{i}},</math>
where
*Φ<sub>e</sub><sup>t</sup> is the [[radiant flux]] ''transmitted'' by that surface into the hemisphere on the opposite side from the incident radiation;
*Φ<sub>e</sub><sup>i</sup> is the radiant flux received by that surface.
Hemispheric transmittance may be calculated as an integral over the directional transmittance described below.