very pretty...though underwater maybe ORANGE better...but how many tools actually get wet ?
http://www.deep-six.com/page77.htm
COLOR UNDERWATER
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The light spectrum is well known. "ROY G. BIV" is an acronym used to remember the colors from one end to the other. From left to right the letters stand for: Red, Orange, Yellow, Green, Blue, Indigo, and Violet. A mixture of all the colors makes white light. If one were to take 7 flashlights, each of which was giving off one of the listed colors, and shine all the different lights on a white wall the spot of light would be white. A white light is composed of all the colors. There are 3 primary colors: Red, blue, and green. If those colors are combined the spot would also be white as is depicted in the picture below.
Water acts as a selective filter. If a white light is suspended above a tank of water that was 1000' deep the colors from the white light would be filtered out selectively (one-by-one) as one descends. It is gradual. There is no abrupt interface. For example, most of the red is gone from the light after 10 feet. Some of the orange is gone. Less of the yellow is lost. At 25' most of the orange is gone. At 35' most of the yellow is gone. This continues through the spectrum until all that is left is violet light and that fades out after hundreds of feet. At the bottom of this 1000' tank of water there would be little or no light.
Selective filtration creates conditions that make diving interesting. If a diver is bleeding at 60', where there is no red light, the diver bleeds a greenish-black blood. Taking a photograph at 30' would result in most objects appearing green, blue, violet, and/or black. Taking the same photograph with a flash (white light) would reveal startling colors that were not seen by the diver. Remember, the selective filtering by water occurs in any direction. So a camera's flash will also loose most of its true color effectiveness after a distance of as little as five feet. That is because the light would leave the camera, hit the object 5 feet away and then return to the camera. In that 10 foot travel distance most of the red would be gone and the orange would be diminished.
The above photograph was taken at a depth of about 50'. The rag in the center is a bright red but at this depth there is little red reflected.
This is the same red rag taken in the same spot with a flash. Notice also the sponges and coral show more color.
LINK TO COLOR PHOTOGRAPHS:
Page 120
The above 2 photos were taken at the same spot in Palau in November 2015. The left is without the video light and the right is with the light. The video light has the characteristics of the sun.
Neon colors do not loose their color like spectrum colors do. This author has video photographed a red stripe on the side of a wet suit turn to black as a diver descended. The stripe could not be seen. On another part of the suit the neon red and "hot pink" still were sending out their bright colors at 100'. That is because they fluoresce. Ultraviolet is found after violet on the spectrum. It is invisible to humans. Like violet it goes to extreme depths. When a neon color is struck by the invisible ultraviolet it glows or fluoresces.
Colors Underwater
One of the first things you notice as a new scuba diver is the surprising lack of color. Discovery Channel specials and magazine layouts have brilliant colors. Where'd they all go?
Don't feel ripped off. The fact is, water absorbs light rapidly. So rapidly, that after only 300 ft (80 m), no visible light remains. This is far deeper than you'll ever go, but this absorption is very important at all depths.
The visible light spectrum can be broken up into the familiar constituent colors (for example, see the too-familiar picture of
Newton with a prism). From least to highest energy, red, orange, yellow, green, blue, and violet. This order is important, because it is the lowest energy colors that are absorbed first in water. This chart below shows the depths at which different colors are absorbed. These are approximate, as water clarity and turbidity affect color absorption.
What is doing the absorbing exactly? All water contains microscopic particles. Light strikes these particles and scatters, with some of the light absorbed. What remains is what color you see. As the light travels farther, only blue light remains, with it eventually being absorbed as well^1^. Of course, flashlights reintroduce "white" light, which contains the entire spectrum, making all colors visible again.
To illustrate, I've recreated how some common items would look at different depths.
Notice how the red is removed from the orange, leaving a little color while the blue text is unaffected.
1. Different particles scatter light differently, so some water appears more green than blue.
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