Fresnel Reflection

The Fresnel effect is wavelength dependent. It behavior is determined by the index-of-refraction of the material (taken as a complex value to allow for attenuation). This effect explains the variation in colors seen in specular regions particular on metals (conductors).

It also explains why most surfaces approximate mirror reflectors when the light strikes them at a grazing angle. This version of the equation ignores the polarization of the incoming and reflected rays.

No mirage without Fresnel