Experimental studies at photon energies between 1.8 and 2.7 eV have recently shown that photodissoication occurs well below the photodetachment threshold for CO-3 and CO-3⋅H2O and dominates the photodestruction of O-3 at visible wavelengths. Experimental cross sections have been averaged over the solar flux spectrum to yield zero optical depth rates. Production of O- by dissociation of CO-3 and CO-3⋅H2O and its subsequent photodetachment can probably account for the rapid increase of electron density in the D region of the ionosphere at sunrise. Photodissociation is also an important daytime loss mechanism for CO-3 and its hydrate in the 50- to 80-km region.