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Light absorption in water

 
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Joined: 24 Oct 2004
Posts: 47
Location: Nearwater

PostPosted: Mon Nov 22, 2004 1:21 am    Post subject: Light absorption in water Reply with quote

The visible light to humans of red through to blue is absorbed in water according to its wavelength and so is absorbed at

differing rates relative to depth (being distance travelled).

Red (around 700nm) is greatest at being absorbed
Then Orange, Yellow, Green
Blue (around

460nm) is least absorbed

In littoral areas of the sea shore, this is significant in that at low tide the full intensity of the full visible spectrum is available (pending

weather and obviously daytime measurements) whereas the same area, as the tide rises, is gradually filtered of its intensity and therefore variations of the visible

wavelength become present.... Red, being the most effected.

Taking a sample UK tidal range of 5 meters in height and water quality with average visibility:
In

these conditions, the transmission of Red light is reduced to around the 0% at the 5 meter depth (based on a 70% reduction per meter)

1m = 70% of 100% =

70%
= 30% transmission remaining

2m = 70% of 30% = 21%
= 9% transmission remaining

3m = 70% of 9% = 6%
= 3% transmission

remaining

4m = 70% of 3% = 2%
= 1% transmission remaining

5m = 70% of 1% = 1%
= 0% transmission remaining

(all data rounded to

nearest%)
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shelley



Joined: 22 Nov 2004
Posts: 7
Location: Plymouth

PostPosted: Thu Nov 25, 2004 11:50 pm    Post subject: Reply with quote

from full to zero is substantial variation... good observation.
Im off to add it to the things that effect the seashore environment bit,

thanks.
Shelley
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