Steve,
you point out "the photons are not encoded in nuclei".
So far. There is yet to be a rationale for the peculiarities of intensity rates of chage in the Transition Zone. The right question should be; 'What do those measurable variations tell us of what determines wavelength?' (lambda)
Now again, in the span of one wavelength, light velocity would take a finite span of time. But the wave doesn't know how fast time goes, it can only be somewhere between nil and light velocity... OR all of the above. so mathematically the physicality can be simplified to the wave seeking what that speed of time is... so going from nil to c and back again at an exponential rate of change would require that c (light velocity) is the root exponential mean of the sum of integral partial differentials for the span of real time relative to the gravitational reference frame and by Lorentz any (luminous aetherial) reference frame the wave subsequently transits through.
So we can postulate that the maximun speed (scalar value) reached in the waveformation is equivalent to [(c^1/e) c } = 2.143^14 cm/sec . And that transcends (e is after all a transcendental number) the locality of the waveform of any single wavelenghth and makes the wavetrain rigidly connected across the real time length of span of emission. The time span at c in each wavelength reaches out across that real proportional extension of length. jrc