Why is the sky blue? Because shorter wavelengths (blue, UV etc) are more susceptible to atmospheric scatter, otherwise known as "Rayleigh scattering".
Longer wavelengths, such as far red and infra-red, have greater penetrating power. So it is no surprise that spectral measurements differ depending on distance from light source in any atmosphere. (Which, in fact, they do.)
Does voltage affect CCT in LEDs? I'm certainly no expert. But on every spec chart I've read, yes voltage does affect CCT shift - the lower the voltage, the lower the CCT; the higher the voltage, the higher the CCT.
Samsung F Series datasheets show the 5000K strips produce 4798K at 43.7v, 4984K at 46.0v ,and 5177K at 48.4v Other CCT strips show a similar pattern.
Why? Well, perhaps the answer is as simple as thermal radiation - the hotter a metal, the higher the "heat" colour (Kelvin). This is certainly true of HIDs. When you dim them, they go redder because they are running cooler. It's like the red glow of a HPS when you turn it off and it immediately starts to cool down; or the transition from red to yellow when you first turn the lamp on and it starts to heat up and stablise to operating temperature.
LEDs give off heat - the higher you drive them, the more heat is given off - so there's no reason for me not to believe the pn junction metals and reflective surface within the LED give off a higher thermal radiation temperature as they get hotter.
That would be my understanding.
