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:
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And going faster and faster: desk, papers, books,
Photographs of friends, the window and the trees
Merging in one neutral band that surrounds
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—John Ashbery (b. 1927)
“When our relatives are at home, we have to think of all their good points or it would be impossible to endure them. But when they are away, we console ourselves for their absence by dwelling on their vices.”
—George Bernard Shaw (1856–1950)