April 22, 2013
Earth Day dawned cold. As the sun warmed the air, I ventured out for a walk. There was one dab of a white cloud in the sky. It looked almost lost; perhaps wondering where all the other clouds had gone. Under a tall Aspen tree, I looked up to see its leaves framed against the bright blue sky. As long as I can remember I have loved the sight of spring green leaves upon a blue sky background. What makes the sky blue? Molecules in the air that scatter blue light from the sun more than they scatter red light.