Surface Illumination
The spectrum of surface illumination depends upon solar elevation due to atmospheric effects, with the blue spectral component from atmospheric scatter dominating during twilight before and after sunrise and sunset, respectively, and red dominating during sunrise and sunset. These effects are apparent in natural light photography where the principal source of illumination is sunlight as mediated by the atmosphere.
According to Craig Bohren, "preferential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon".
See diffuse sky radiation for more details.
Read more about this topic: Sunlight
Famous quotes containing the words surface and/or illumination:
“Here Men from The Planet Earth
First Set Foot upon The Moon
July, 1969 AD
We Came in Peace for All Mankind”
—Plaque left behind on the moon’s surface by the crew of Apollo 11.
“When we want culture more than potatoes, and illumination more than sugar-plums, then the great resources of a world are taxed and drawn out, and the result, or staple production, is, not slaves, nor operatives, but men,—those rare fruits called heroes, saints, poets, philosophers, and redeemers.”
—Henry David Thoreau (1817–1862)