Visible Light Beams
From the side, a beam of light is only visible if part of the light is scattered by objects: tiny particles like dust, water droplets (mist, fog, rain), hail, snow, or smoke, or larger objects such as birds. If there are many objects in the light path, then it appears as a continuous beam, but if there are only a few objects, then the light is visible as a few individual bright points. In any case, this scattering of light from a beam, and the resultant visibility of a light beam from the side, is known as the Tyndall effect.
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Famous quotes containing the words visible, light and/or beams:
“All visible objects, man, are but as pasteboard masks. But in each event—in the living act, the undoubted deed—there, some unknown but still reasoning thing puts forth the mouldings of its features from behind the unreasoning mask. If man will strike, strike through the mask!”
—Herman Melville (1819–1891)
“The press is no substitute for institutions. It is like the beam of a searchlight that moves restlessly about, bringing one episode and then another out of darkness into vision. Men cannot do the work of the world by this light alone. They cannot govern society by episodes, incidents, and eruptions. It is only when they work by a steady light of their own, that the press, when it is turned upon them, reveals a situation intelligible enough for a popular decision.”
—Walter Lippmann (1889–1974)
“The highway presents an interesting study of American roadside advertising. There are signs that turn like windmills; startling signs that resemble crashed airplanes; signs with glass lettering which blaze forth at night when automobile headlight beams strike them; flashing neon signs; signs painted with professional touch; signs crudely lettered and misspelled.... They extol the virtues of ice creams, shoe creams, cold creams;...”
—For the State of Florida, U.S. public relief program (1935-1943)