This demonstration addresses the questions: “why is the sunset red?,” and “why is the sky blue?” When light from the bulb passes through the dry milk in water it simulates the scattering of sunlight in the atmosphere during the sunset. The jack should be adjusted (see pictures) so the students can compare the colors of the filament and of the scattered light.

List of parts:

• Unfrosted bulb in a ceramic socket
• Square glass tank filled with water and dry milk
• Lab jack
• Variac

Note: Put enough dry milk so that the filament of the bulb appears to be red as you look at it through the water.