Light Attenuation for Various Colors of Light in Water

A light's wavelength is directly related to how deep the light can penetrate a body of water.  As light travels through water, it is scattered and absorbed by the water molecules, ions and particulates in the water.  The decrease in light intensity over distance is referred to as attenuation. 

Beer's Law can be used to determine how much of a light source reaches what depth of water based on its wavelength and corresponding attenuation coefficient.  Based on the attenuation coefficients for red, orange*, yellow, green, blue and voilet light, their calculated % Incident Light versus Depth of Water are shown below in Figure 1.  All colors start at a % Incident Light of 1% because the natural log cannot be taken for 0%. 

Figure 2 shows the same information but on a logarithmic scale to yield straight lines. 

*Note: Two coefficients were given for the color range of orange so the graphs show lines for an Orange1 with a coefficient of 0.650m^-1 and an Orange2 with a coefficient of 0.350m^-1. 

 Figure 1

Figure 2

As the figures suggest, as a light's wavelength increases (red has the largest wavelength, violet has the smallest) the light is attenuated more quickly.  Hence, colors like red and orange attenuate much faster than blues and violet.