View the glare from the lake surface to determine the polarization axis.
Work Step by Step
If the reflective surface is nonmetallic, much of the reflected light is polarized. The polarization direction is parallel to the direction of the reflecting surface. In the case of a lake surface, the reflected light will be polarized horizontally. This is discussed on page 556, and diagrammed in Figure 29.33. If you view the glare off the lake surface, the glare is most intense when the polarization axis is horizontal.