Figure 3. Absorption of blue skylight by UV rhodopsin, N_iF_a(κ), as a function of length l_r.

The exact calculation (black solid line) is very different from exponential absorption at the peak wavelength (black dashed line). Our approximation to F_a(κ), (Eq. (9), red dotted line), fits better at very short lengths than approximation made by Warrant & Nilsson (1998) (blue dashed line). Parameters used for calculations as in subscript to Fig. 2.