Not buying into a change in the sun’s spectrum, though in the seasons we do see a range of increasing intensities of the sun’s rays when moving from the winter (lower in the sky), to spring and on to summer (where the sun’s directly overhead. That along with the increasing period of time those same more intense rays are reaching the earth.
The argument that in winter we’re seeing more reds is only true at sunrise and sunset when dust or clouds are present to scatter the light, that our eyes are more sensitive to those orange/ yellow frequencies of light would then follow that we’d perceive a brighter winter than we do, which isn’t true...
So the conclusion I’m left with is that plants and by that I mean MJ has its own unique set of ideal conditions which we’re all striving to duplicate artificially by any means we select...that we’re able to do this via utilizing lighting and timing schemes just allows us the freedom to enjoy this engaging pastime...