Glitter Path

A glitter path is the reflection of a light source, often the sun, off a water surface covered by small waves and ripples. The many small reflecting surfaces of the faces of the waves and ripples cause many individual glitters which add up to a distorted reflection of the light source. The small deviations away from the horizontal away and towards the observer cause the reflection to be strongly elongated in the vertical direction. The effect is very similar to light pillars caused by reflections off horizontally oriented plate ice crystals in the air.

The maximum vertical extent of the glitter path is twice - angle of incidence plus the angle of reflection - the maximum inclination of the waves above and below the direct reflection of the light source, which gives a total extent of 4 times the maximum inclination of the waves. Once the sun is less than twice the maximum inclination of the waves above the horizon, the glitter path reaches the horizon and is truncated. The width of the glitter path is proportional to the sine of the hight of the sun and maximum inclination of the waves. Thus the higher the sun or steeper the waves the wider the glitter path. As the sun gets very low the height of the waves shadow the faces of the waves, so only the crests are illuminated, causing the glitter path to all but disappear.

When the sun is low, less than twice the maximum inclination of the waves, the glitter path is truncated at the horizon.

A glitter path caused by ripples in blue ice on the Antarctic plateau.

The glitter path almost disappears as the sun gets very low.