Polarization by Reflection
Unpolarized light has equal amounts of vertical and horizontal polarization. After interaction with a surface, the vertical components are preferentially absorbed or refracted, leaving the reflected light more horizontally polarized. This is akin to arrows striking on their sides bouncing off, whereas arrows striking on their tips go into the surface.
Source
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"OpenStax College, Polarization. January 13, 2013."
http://cnx.org/content/m42522/latest/
OpenStax CNX
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