Neutral Points
There are three commonly detectable points of zero polarization of diffuse sky radiation (known as neutral points) lying along the vertical circle through the sun.
- The Arago point, named after its discoverer, is customarily located at about 20° above the antisolar point; but it lies at higher altitudes in turbid air. The latter property makes the Arago distance a useful measure of atmospheric turbidity.
- The Babinet point, discovered by Babinet in 1840, is located about 15° to 20° above the sun, hence it is difficult to observe because of solar glare.
- The Brewster point, discovered by Brewster in 1840, is located about 15° to 20° below the sun; hence it is difficult to observe because of solar glare.
Read more about this topic: Diffuse Sky Radiation
Famous quotes containing the words neutral and/or points:
“The lonely Earth amid the balls
That hurry through the eternal halls,
A makeweight flying to the void,
Supplemental asteroid,
Or compensatory spark,
Shoots across the neutral Dark.”
—Ralph Waldo Emerson (18031882)
“Only that which points the human spirit beyond its own limitations into what is universally human gives the individual strength superior to his own. Only in suprahuman demands which can hardly be fulfilled do human beings and peoples feel their true and sacred measure.”
—Stefan Zweig (18811942)
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