simpleword
Active member
Just curious why any plant would evolve with such needs, since the sun is always the same spectrum.
Ahh but it's not. In the fall when the days are shorter, the sun is lower in the sky, causing a lower angle of incidence. The light is filtered through much more atmosphere than sunlight directly above you. Blue light is scattered more easily, thus there is a higher percentage of red light.
Same reason sunsets are red and orange.