PURKINJE EFFECT

Forty years ago, a good friend and neighbor, Fred McLeod of Windsor, CT introduced me to the Purkinje effect. Fred explained how late-in-day sunshine played tricks with our vision. He said "the grass looks greener" as the sun prepares to set!


 Wikipedia says "there is a tendency for the peak luminance sensitivity of the human eye to shift toward the blue end of the color spectrum at low illumination levels."


"This effect introduces a difference in color contrast under different levels of illumination. For instance, in bright sunlight, geranium flowers appear bright red against the dull green of their dull leaves, or adjacent blue flowers, but in the same scene viewed at dusk, the contrast is reversed, with red petals appearing a dark red or black, and the leaves and blue petals appearing relatively bright.


Now I am not appealing you to get a physics book but instead to notice how colors change. Become aware of very green grass in the last hour of daylight!