“The light from the sky is a result of the scattering of sunlight, which results in a light blue color perceived by the human eye. On a sunny day Rayleigh Scattering gives the sky a blue gradient — dark in the zenith, light near the horizon. Light that comes in from overhead encounters an air mass 1/38th of the mass of the air for a sunbeam coming along a horizon path. So, fewer particles scatter the zenith sunbeam, and therefore the light remains a darker blue.
The sky can turn a multitude of colors such as red, orange and yellow (especially near sunset or sunrise) and black at night. Scattering effects also partially polarize light from the sky.”
“Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from Greek: χλωρός (chloros “green”) and φύλλον (phyllon “leaf”). Chlorophyll absorbs light most strongly in the blue and red but poorly in the green portions of the electromagnetic spectrum, hence the green colour of chlorophyll-containing tissues like plant leaves.”