The Color of Snow - Perception versus Physiology

If you always thought snow was white - think again!

The colors we perceive and the colors that impact our health are not the same. Without thinking we tend to make decisions about the color of light and our surroundings based on what we perceive. But the colors that our bodies react to, and modulate our physiological functions, are quite different and are not readily apparent.

What is the color of freshly fallen snow? It is white, of course, you will tell me. It has always been white. Phrases such as “White as driven snow” from Shakespeare’s The Winter’s Tale, are embedded in our literature and culture. How could snow be anything other than white?

But if we examine the color of the light wavelengths entering our eyes on a snowy day none of them are white. Light reflected off snow contains every color of the rainbow. It is particularly rich in blue, but violet, green, yellow, orange, and red are all fully represented.

The color spectra detected by a spectrophotometer pointed at the overcast grey sky, and then pointed at the snow on the ground.

The sky may be grey, but it has the same distribution of color wavelengths because snow is an excellent reflector of every light color wavelength. The intensity of the light reflected from snow is about 50% of every wavelength arriving from the sky. It is that perfect balance of wavelengths that makes the snow appear white.

This matters because our perception of color does not enable us to judge whether the light we see is good for our health. We cannot easily tell whether a light is rich in blue and therefore harmful in the evening hours, or is weak in blue wavelengths and therefore not healthy for daytime use. The percentage blue content and the intensity of the light entering your eyes are both vital to know before you select a light.

Winter is almost over. Take every opportunity you can to go for a daily walk in the snow, even if the sky is grey, for this will bathe you in the bountiful healthy blue-rich light beloved by our circadian clocks. It will also dose you with the green wavelengths that sooth our amygdala, and the red wavelengths that heal us. You will perceive the snow as white but you now know that it is rich in the colors of healthy light.