| Definition: | quotient of the radiant flux dΦe leaving an element of the surface containing the point, by the area dA of that element
Equivalent definition. Integral, taken over the hemisphere visible from the given point, of the expression Le • cos θ · dΩ, where Le is the radiance at the given point in the various directions of the emitted elementary beams of solid angle dΩ, and θ is the angle between any of these beams and the normal to the surface at the given point
X
unit : W • m-2
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