Sylvanshine is an
optical phenomenon in which
dew-covered
foliage with
wax-coated leaves
retroreflect beams of light, as from a vehicle's
headlights. This effect sometimes makes trees appear snow-covered at night during the summer. The phenomenon was named and explained in 1994 by Alistair Fraser of
Pennsylvania State University, an expert in
meteorological optics. According to his explanation, the
epicuticular wax on the leaves causes water to form beads, which in effect, become
lenses. These lenses focus the light to a spot on the
leaf surface, and the image of this spot is directed as rays in the
opposite direction.