Color of water 1

Color of waterFor the book by James McBride, see The Color of Water.

When water is in small quantities(e.g. in a glass) it appears colorless to

the human eye

While relatively small quantities of water appear to be colorless, water's tintbecomes a deeper blue as the thickness of the observed sample increases. Theblue hue of water is an intrinsic property and is caused by selective absorptionand scattering of white light. Impurities dissolved or suspended in water maygive water different colored appearances.

Intrinsic color

For more details on this topic, see Electromagnetic absorption by water.

An indoor swimming pool appears blue fromabove, as light reflecting from the bottom of thepool travels through enough water that its redcomponent is absorbed. The same water in a

smaller bucket looks only slightly blue

The intrinsic color of liquid water may be demonstrated by looking at awhite light source through a long pipe that is filled with purified waterand closed at both ends with a transparent window. The light turquoiseblue color is caused by weak absorption in the red part of the visiblespectrum.[1]

For most substances, absorptions in the visible spectrum are usuallyattributed to excitations of electronic energy states. However, water isa simple 3-atom molecule, H2O, and all its electronic absorptions occurin the ultraviolet region of the electromagnetic spectrum and aretherefore not responsible for the color of water in the visible region ofthe spectrum.Wikipedia:Citation needed

The water molecule has three fundamental modes of vibration,including two stretching vibrations of the O-H bonds which occur at v1= 3650cm1 and v3 = 3755cm

1. Absorption due to these vibrations occurs in the infrared region of the spectrum.The absorption in the visible spectrum is due mainly to the harmonic v1 + 3v3 = 14,318cm

1, which is equivalent toa wavelength of 698nm.[1]

Absorption intensity decreases markedly with each successive overtone, resulting in very weak absorption for thethird overtone. For this reason, the pipe needs to have a length of a meter or more and the water must be purified bymicrofiltration to remove any particles that could produce Rayleigh scattering.Wikipedia:Citation needed

Color of water 2

Color of lakes and oceans

Large bodies of water such as oceans manifestwater's inherent slightly blue color.

Lakes and oceans appear blue for several reasons. One is that thesurface of the water reflects the color of the sky. While this reflectioncontributes to the observed color, it is not the sole reason.[2]

Some constituents of sea water can influence the shade of blue of theocean. This is why it can look greener or bluer in different areas. Waterin swimming pools (which may also contain various chemicals) withwhite-painted sides and bottom will appear as a turquoise blue.Clean water appears blue in white-tiled swimming pools as well as inindoor pools where there is no blue sky to be reflected. The deeper thepool, the bluer the water. Scattering from suspended particles alsoplays an important role in the color of lakes and oceans. A few tens of

meters of water will absorb all light, so without scattering, all bodies of water would appear black. Because mostlakes and oceans contain suspended living matter and mineral particles, known as colored dissolved organic matter(CDOM) light from above is reflected upwards. Scattering from suspended particles would normally give a whitecolor, as with snow, but because the light first passes through many meters of blue-colored liquid, the scattered lightappears blue. In extremely pure wateras is found in mountain lakes, where scattering from white-colored particlesis missingthe scattering from water molecules themselves also contributes a blue color.Wikipedia:Citation needed

The hue of the reflected sky also contributes tothe perceived color of water.

Another phenomenon that occurs is Rayleigh scattering in theatmosphere along one's line of sight: the horizon is typically 45kmdistant and the air (being just above sea level in the case of the ocean)is at its densest. This mechanism would add a blue tinge to any distantobject (not just the sea) because blue light would be scattered into one'sline of sight.Wikipedia:Citation needed

The surfaces of seas and lakes often reflect blue skylight, making themappear bluer. The relative contribution of reflected skylight and thelight scattered back from the depths is strongly dependent onobservation angle.[3]

Color of water 3

Color of glaciersMain article: Blue ice (glacial)Glaciers are large bodies of ice and snow formed during very cold climates by processes involving the compaction offallen snow. While snowy glaciers appear white from a distance, up close and when shielded from direct ambientlight, glaciers usually appear a deep blue due to the long path lengths of the internal reflectedlight.Wikipedia:Citation needed

Color of water samples

High concentrations of dissolved lime give thewater of Havasu Falls a turquoise color.

Dissolved and particulate material in water can cause discoloration.Slight discoloration is measured in Hazen units (HU).[4] Impurities canbe deeply colored as well, for instance dissolved organic compoundscalled tannins can result in dark brown colors, or algae floating in thewater (particles) can impart a green color.

The color of a water sample can be reported as: Apparent color is the color of the whole water sample, and consists

of color from both dissolved and suspended components.

True color is measured after filtering the water sample to remove allsuspended material.

Testing for color can be a quick and easy test which often reflects theamount of organic material in the water, although certain inorganiccomponents like iron or manganese can also impartcolor.Wikipedia:Citation needed

Water color can reveal physical, chemical and bacteriologicalconditions. In drinking water, green can indicate copper leaching fromcopper plumbing and can also represent algae growth. Blue can alsoindicate copper, or might be caused by syphoning of industrial cleanersin the tank of commodes, commonly known as backflowing. Reds can be signs of rust from iron pipes or airbornebacteria from lakes, etc. Black water can indicate growth of sulfur-reducing bacteria inside a hot water tank set atless than 120 degrees Fahrenheit. This usually has a strong sulfur or rotten egg (H2S) odor and is easily corrected bydraining the water heater and increasing the temperature to 120 or higher. The odor will always be in the hot waterpipes if sulfate reducing bacteria are the cause and never in the cold water plumbing. The color spectrum with waterindicatorsWikipedia:Please clarify is wide and, if learned, can make solving cosmetic, bacteriological and chemicalproblems easier to identify.Wikipedia:Citation needed

Color of water 4

Water quality and color

Glacial rock flour makes New Zealand's LakePukaki a lighter turquoise than its neighbors.

The presence of color in water does not necessarily indicate that thewater is not drinkable. Color-causing substances such as tannins maybe harmless.Wikipedia:Citation needed

Color is not removed by typical water filters; however, slow sandfilters can remove color, and the use of coagulants may also succeed intrapping the color-causing compounds within the resultingprecipitate.Wikipedia:Citation needed

Other factors can affect the color we see: Particles and solutes can absorb light, as in tea or coffee. Green

algae in rivers and streams often lend a blue-green color. The RedSea has occasional blooms of red Trichodesmium erythraeum algae.Wikipedia:Citation needed

Particles in water can scatter light. The Colorado River is often muddy red because of suspended reddish silt inthe water. Some mountain lakes and streams with finely ground rock, such as glacial flour, are turquoise. Lightscattering by suspended matter is required in order that the blue light produced by water's absorption can return tothe surface and be observed. Such scattering can also shift the spectrum of the emerging photons toward thegreen, a color often seen when water laden with suspended particles is observed.Wikipedia:Citation needed

Color names

Red tide off the California coast.

Various cultures divide the semantic field of colors differently from theEnglish language usage and some do not distinguish between blue andgreen in the same way. An example is Welsh where glas can meanblue or green.

Other color names assigned to bodies of water are sea green andultramarine blue. Unusual oceanic colorings have given rise to theterms red tide and black tide.

The Ancient Greek poet Homer uses the epithet "wine-dark sea"; inaddition, he also describes the sea as "grey". Some have suggested thatthis is due to the Ancient Greeks classifying colors primarily byluminosity rather than hue, while others believe Homer was color-blind.Wikipedia:Citation needed

References[1] Braun & Smirnov 1993, p.612.[2][2] ":"...any simple answer is bound to mislead. It turns out that contributions to the observed color are made both by reflected skylight and by

the intrinsic absorption...""[3] "...the relative contribution of reflected skylight and the light scattered back from the depths is strongly dependent on observation angle."

Charles L. Braun and Sergei N. Smirnov WHY IS WATER BLUE? J. Chem. Edu., 1993, 70(8), 612 added some sugar too http:/ / www.dartmouth. edu/ ~etrnsfer/ water. htm

[4] International Organization for Standardization, ISO 2211:1973, Measurement of colour in Hazen units (platinum-cobalt scale) of LiquidChemical Products

Braun, Charles L.; Smirnov, Sergei N. (1993), "Why is water blue?" (http:/ / inside. mines. edu/ fs_home/ dwu/classes/ CH353/ study/ Why is Water Blue. pdf), Journal of Chemical Education 70 (8): 612614, Bibcode:1993JChEd..70..612B (http:/ / adsabs. harvard. edu/ abs/ 1993JChEd. . 70. . 612B), doi: 10.1021/ed070p612(http:/ / dx. doi. org/ 10. 1021/ ed070p612)

Color of water 5

Further reading Dickey, Tommy D.; Kattawar, George W.; Voss, Kenneth J. (April 2011), "Shedding new light on light in the

ocean" (http:/ / www. nserc. und. edu/ learning/ Dickeyetal2011. pdf), Physics Today 64 (4): 4449, Bibcode:2011PhT....64d..44D (http:/ / adsabs. harvard. edu/ abs/ 2011PhT. . . . 64d. . 44D), doi: 10.1063/1.3580492 (http:// dx. doi. org/ 10. 1063/ 1. 3580492)

Pettit, Edison (February 1936), "On the Color of Crater Lake Water", Proceedings of the National Academy ofSciences of the United States of America 22 (2): 139146, Bibcode: 1936PNAS...22..139P (http:/ / adsabs.harvard. edu/ abs/ 1936PNAS. . . 22. . 139P), doi: 10.1073/pnas.22.2.139 (http:/ / dx. doi. org/ 10. 1073/ pnas. 22.2. 139), PMC 1076722 (http:/ / www. ncbi. nlm. nih. gov/ pmc/ articles/ PMC1076722), PMID 16588059 (http:// www. ncbi. nlm. nih. gov/ pubmed/ 16588059)

External links What color is water? (http:/ / webexhibits. org/ causesofcolor/ 5B. html) Why is Water Blue? (http:/ / www. dartmouth. edu/ ~etrnsfer/ water. htm) Is water blue? The absorption spectrum of water in the visible range (http:/ / www. lsbu. ac. uk/ water/ vibrat.

html#blue) Why is the snow blue? (http:/ / www. discovery. com/ area/ skinnyon/ skinnyon971003/ skinnyon. html#blue) The Color of the Ocean (http:/ / nasascience. nasa. gov/ earth-science/ oceanography/ living-ocean/ ocean-color)

from science@nasa Why is it blue? (http:/ / www. whyiswaterblue. com) Is water clear? (http:/ / www. whyzz. com/ why-is-water-clear)

Article Sources and Contributors 6

Article Sources and ContributorsColor of water Source: http://en.wikipedia.org/w/index.php?oldid=619963914 Contributors: Adoniscik, AgentPeppermint, Aitias, Alphapeta, Atlant, Avenue, Avoided, Barneca, Beetstra,Beland, Bobak, Bobo192, Callooooom, Chelseafan528, Chriswaterguy, Cliff12345, David spector, Deglr6328, Denisarona, Dhaluza, Donner60, Doulos Christos, Dricherby, Dude1818, Edison,Ehrenkater, Epbr123, Epipelagic, Eric, Excirial, Executive.samuel, Fastilysock, FayssalF, Flyguy649, Fredrick Larson, Geschichte, Ginsuloft, Glimb, Halaqah, Highway99, Idexa, Incredio,JacksonTan, Jake Wartenberg, Jchthys, Jeff G., Jrockley, Jrtayloriv, Kbrose, Kfogel, Krang, Kuru, Lambiam, Leafyplant, Little Mountain 5, Logan, M3tainfo, Madhero88, Magioladitis, Mairi,Materialscientist, Melchoir, Mentifisto, Missing Ace, Mixalis007, Mr swordfish, Mr.Z-man, Nono64, Notfed, Nsaa, Ost316, Panek, Paul Hackney, Peachypoh, Pengo, Petergans, Peti me, Petrb,Piano non troppo, Pinethicket, Quiddity, RDBrown, Reaper Eternal, Robinh, Ronhjones, Saranshi Gupta, Sceptre, Serasuna, Shalom Yechiel, Simulcra, Speight, Stanleysage, Stephenb, Sturm55,Swpb, Tagishsimon, Tanaats, Tbhotch, The High Fin Sperm Whale, The Letter J, The Thing That Should Not Be, TheFeds, Tideflat, Tim-weddepohl, Tom, Ulmanor, V8rik, Valoem, WayneSlam, Widr, Wikipelli, Wjbeaty, Xanzzibar, Yamamoto Ichiro, Ybbor, Yossiea, 218 anonymous edits

Image Sources, Licenses and ContributorsFile:Strawberry splash.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Strawberry_splash.jpg License: Creative Commons Attribution 2.0 Contributors: Abhijit TembhekarFile:SwimmingPoolAndBucket.jpg Source: http://en.wikipedia.org/w/index.php?title=File:SwimmingPoolAndBucket.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors:IncredioFile:Ireland-AtlanticOceanwithAranIsland.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Ireland-AtlanticOceanwithAranIsland.jpg License: Creative CommonsAttribution-ShareAlike 1.0 Generic Contributors: Man vyi, Menchi, Ronline, 1 anonymous editsFile:Ocean color 2007.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Ocean_color_2007.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Ulmanor (talk)File:Havasu Falls 2 md.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Havasu_Falls_2_md.jpg License: Creative Commons Attribution-Sharealike 2.5 Contributors:User:MoondiggerFile:Lake Pukaki and neighbours - STS088-721-15.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Lake_Pukaki_and_neighbours_-_STS088-721-15.jpg License: Public DomainContributors: Lake_Pukaki_-_STS088-721-15.JPG: Johnson Space Center derivative work: Avenue (talk)File:La-Jolla-Red-Tide.780.jpg Source: http://en.wikipedia.org/w/index.php?title=File:La-Jolla-Red-Tide.780.jpg License: Public Domain Contributors: Alan, CL8, Courcelles, Fiver, derHellseher, Mattes, Mortadelo2005, Saperaud, TED, 2 anonymous edits

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Color of waterIntrinsic colorColor of lakes and oceansColor of glaciersColor of water samplesWater quality and colorColor namesReferencesFurther readingExternal links

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