Sylvanshine

Sylvanshine is an optical phenomenon in which dew-covered trees of species whose leaves are wax-covered retroreflects beams of light, as from a vehicle's headlights, sometimes causing trees to appear to be snow-covered at night during the summer. The phenomenon was named and explained in 1994 by Professor Alistair Fraser of Pennsylvania State University, an expert in meteorological optics. According to his explanation, the wax on the leaves causes water to form beads, which become, in effect, lenses.

Reference

Alistair B. Fraser. The Sylvanshine: retroreflection in dew-covered trees. Applied Optics., 33, 21, 4539-4547. 1994