What is Optical depth?
'''Optical depth''' is a measure of [[transparency]]. It is defined as the [[Fraction (mathematics)|fraction]] of [[radiation]] (or [[light]]) that is scattered or absorbed on a path. One way of visualizing optical depth is to think of a fog. The [[fog]] between a person and an object that is immediately in front of them has an optical depth of zero. As the object moves away, the optical depth increases until it reaches a large value and the object is no longer visible. ==Other websites== * [http://scienceworld.wolfram.com/physics/OpticalDepth.html optical depth equations] {{science-stub}} [[Category:Light]]