Figure 1:

(Top) Mean daily solar insolation (W m⁻² per planetary day) incident onto a unit horizontal surface at the top of the atmosphere of Uranus (Left) and Neptune (Right) as a function of planetocentric latitude and season, where season is represented by solar longitude L_s. (Bottom) Mean daily actinic flux (W m⁻² per planetary day) at the top of the atmosphere of Uranus (Left) and Neptune (Right) as a function of planetocentric latitude and season. Note that a molecule being photodissociated does not care what direction the photon is coming from, just what the local photon flux is; therefore, the actinic flux, which is the solar flux without accounting for the cosine dependence of the solar zenith angle, is more relevant to the photochemistry discussion than the insolation at a “surface.”