Depletion of solar radiation at discrete wavelengths by nitric oxide has a significant impact on the dissociation rate of this gas in the Δ(0,0) and Δ(1,0) bands. Inclusion of the opacity provided by a typical NO profile reduces the dissociation rate in the upper stratosphere to 50--70% of that predicted when the optical depth calculation omits this contribution. A substantial fraction of the nitric oxide column abundance as measured near the stratopause resides in the lower thermosphere where correlations of NO with solar and magnetic activity are well documented. Variations in the thermospheric NO abundance therefore modulate the radiation field at the precise wavelengths absorbed by this molecule in the mesosphere and upper stratosphere. Predicted changes in the dissociation rate arising from a varying thermospheric opacity exceed 8% throughout the mesosphere and reach 15% between 65 km and 95 km.