Is the polarization of light from the blue sky vertical / horizontal / at some angle? How do you prove it?

Question

Is the polarization of light from the blue sky vertical / horizontal / at some angle? How do you prove it?

I suspect that it is vertical as sunglasses are designed with their polarization axis being horizontal to cut away glare. I may be wrong though, hence I need input from you guys. Thanks in advance.

Answer 1

Skylight is unpolarized, as can be detected by a pair of polarized sunglasses. The ambient light seen through them is unchanged by their orientation. Sunglasses are polarized to help reduce glare from ground reflection. When ambient sunlight reflects off of the horizontal ground, the portion that is reflected most is the portion that was horizontally polarized to begin with, so the reflected light has a higer portion of horizontally polarized light than any other polarization angle. The glasses are vertically polarized to reject this light and thus reduce the reflected glare.

Answer 2

If you take the two lenses from a (broken?) pair of polarized sun glasses and overlap them (lens on lens) you can rotate one lens to increase or decrease the light getting through. If there is minimum light getting through, light of both polarities is being blocked. Use this to observe any light source such as sun light. If the light source is strongly polarized, rotating the lenses will not have the same effect but rotating one lens should block the polarized light.

Un-polarized sunlight reflecting off water (while boating?) can become polarized and polarized sunglasses can reduce the glare allowing you to see through the surface.

Answer 3

Light from the sky is diffuse, not polarized.
Polarized glasses are meant to deal with reflected light which is polarized.

Answer 4

Go check my answer to your same question in the Engineering section.