Man's physical universe

xanabras

426 ENERGY MAY BE PROPAGATED BY VIBRATIONS

spectrum.

Under these conditions the light scattered in any direction

perpendicular to the light beam is polarized. The sky is blue due to

Fig. 191. Left, without Pola screen. Right, Pola screen darkens the sky

because the light from the direction at right angles to the sun is partially polarized.

(Courtesy of The Polaroid Corporation.)

this scattering effect, and the clearer the air is the bluer the sky is,

because it is the smaller air molecules rather than the larger dust

particles that are scattering the light. Remember that the smaller

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Fig. 192. Left, unretouched photograph through ordinary anti-glare glasses.

Right, simultaneous photograph identical exposure through Polaroid glasses.

(Courtesy of The Polaroid Corporation.)

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