Editing Reflectance (section)

==Water reflectance==
[[File:Water reflectivity.jpg|thumb|400px|Reflectance of smooth water at 20&nbsp;°C (refractive index 1.333)]]

Reflection occurs when light moves from a medium with one [[index of refraction]] into a second medium with a different index of refraction.

Specular reflection from a body of water is calculated by the [[Fresnel equations]].<ref name="Ottav">Ottaviani, M. and Stamnes, K. and Koskulics, J. and Eide, H. and Long, S.R. and Su, W. and Wiscombe, W., 2008: '[https://journals.ametsoc.org/doi/pdf/10.1175/2007JTECHA1049.1 Light Reflection from Water Waves: Suitable Setup for a Polarimetric Investigation under Controlled Laboratory Conditions]''. Journal of Atmospheric and Oceanic Technology, '''25 (5)''', 715--728.</ref> Fresnel reflection is directional and therefore does not contribute significantly to [[albedo]] which primarily diffuses reflection.

A real water surface may be wavy. Reflectance, which assumes a flat surface as given by the [[Fresnel equations]], can be adjusted to account for [[waviness]].