A Two-For!

Why is grass green & why is the sky blue? – Vogman from Pittsburgh

Both excellent questions, Vogman. Thanks for asking.

The green color of leaves & plants is due to the chemical chlorophyll which is necessary for photosynthesis. Photosynthesis is the process by which most plants get nutrition. Besides chlorophyll, it also requires other things, most importantly light. This is why plants need sunlight to survive. Chlorophyll also happens to be a pigment, thus giving things a green color.

The sky actually contains all colors of the spectrum but the composition of the atmosphere acts like a prism. This means that various colors of the visible spectrum are represented differently depending on their wavelength. The sky technically isn’t blue but appears that way to us because of physics.

Varient atmospheric conditions make different colors visible under specific conditions, such as when you see a colorful sunset. The more “stuff” in the atmosphere (smog, dirt, etc.) the prettier the sunset. Great for the eyes, not so great for the lungs.