Color Color Color (American English), or colour (Commonwealth English), is the characteristic of human visual perception described through color "categories", with names such as red, orange, yellow, green, blue, or purple. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the visible spectrum. Color categories and physical specifications of color are associated with objects through the wavelength of the light that is reflected from them. This reflection is governed by the object's physical properties such as light absorption, emission spectra, etc. By defining a color space, colors can be identified numerically
Forel-Ule scale sea and lake water colors, as they appear to an observer ashore or on board a vessel. The method is used in conjunction with the Secchi disk submersed to half the Secchi depth. The method was developed by François-Alphonse Forel and was three years later extended with greenish brown to cola brown colors by the German limnologist Willi Ule. The Forel Ule scale, a color comparator scale, has been described by Wernand and van der Woerd (M. R. Wernand, H. J. van der Woerd, "Spectral analysis of the Forel-Ule Ocean colour comparator scale.", J. Europ. Opt. Soc. Rap. Public. 10014s