Where I live, some leaves change color as Autumn emerges. How beautiful! The burnt orange and fiery scarlets zing into my optic nerves!
What changes the colors? Why do they turn from green to yellow and orange and red? One possible answer lies within the angle of the Sun and the efficiency at which leaves can process visible light…. the lower the angle of the Sun, certain wavelengths of light get absorbed by the increased thickness of atmosphere that the light must travel through due to the low angle in the sky. So, the leaves evolved to change color to become more efficient at transferring the Sun’s energy into plant energy.
That’s a blunt scientific explanation, but it is awesome to think about. How clever!!
However, it answers the question from a mechanistic slant.
Utterly complex yet it unfolds without contemplation.