Under An Overcast Sky
There is essentially no direct sunlight under an overcast sky, so all light is then diffuse sky radiation. The flux of light is not very wavelength dependent because the cloud droplets are larger than the light's wavelength and scatter all colors approximately equally. The light passes through the translucent clouds in a manner similar to frosted glass. The intensity ranges (roughly) from 1⁄6 of direct sunlight for relatively thin clouds down to 1⁄1000 of direct sunlight under the extreme of thickest storm clouds.
Read more about this topic: Diffuse Sky Radiation
Famous quotes containing the word sky:
“In every landscape, the point of astonishment is the meeting of the sky and the earth, and that is seen from the first hillock as well as from the top of the Alleghanies. The stars at night stoop down over the brownest, homeliest common, with all the spiritual magnificence which they shed on the Campagna, or on the marble deserts of Egypt.”
—Ralph Waldo Emerson (1803–1882)