Demos: 7B-19 Blue Sky, Yellow Sun
A beaker filled with filtered water is placed on a projector so that the beaker is illuminate from below. The water represents the earth's atmosphere while the light source represents the sun. The light transmitted through the "atmosphere" is projected onto a screen.
Ask the audience to characterize the color of the transmitted and scattered light (i.e., that which reaches their eyes through the sides of the glass beaker. Give one student a polarizing filter and ask him/her if the light emerging from the sides of the beaker is polarized.
Now, add one small pinch of coffee creamer to the beaker and stir. This may not be sufficient to see a yellow "sun." If not, add a second pinch and stir. Now the light on the screen should definitely have a yellow hue while the light from the beaker (at 90 degrees with respect to the unpolarized light source) is both bluish in hue and partially polarized.