The water color varies with ambient conditions where water is present. While the relatively small amount of water appears colorless, the pure water has a slight blue color that becomes more blue as the observed sample thickness increases. The blue water color is an intrinsic property and is caused by selective absorption and white light scattering. The dissolved element or suspended dirt can provide different color water.
Video Color of water
Warna intrinsik
The intrinsic color of liquid water can be shown by looking at a white light source through a long tube filled with pure water and closed on both ends with a transparent window. The bright turquoise blue color is caused by weak absorption in the red part of the visible spectrum.
Absorption in the visible spectrum is usually associated with the excitation of the electronic energy state in the material. Water is a simple three-atom molecule, H 2 O, and all its electronic uptake takes place in the ultraviolet region of the electromagnetic spectrum and is therefore not responsible for the color of the water in the visible region of the spectrum. Water molecules have three basic modes of vibration. Two vibrational stretching of the OH bond in the state of a gas gas occurs at v 1 = 3650Ã, cm -1 and v 3 = 3755Ã, cm -1 . Absorption due to this vibration occurs in the infrared region of the spectrum. The absorption in the visible spectrum is mainly due to the harmonic v 1 Ã, Ã, 3v 3 = 14,318Ã, cm -1 , which is equivalent to long wave 698 nm. In a liquid state at 20 ° C this vibration shifts red due to hydrogen bonding, resulting in a red absorption at 740 nm, other harmonics such as v 1 Ã, v 2 Ã, Ã, 3v 3 gives the red absorption at 660Ã, nm. The water absorption curve for heavy water (D 2 O) has the same shape, but it shifts farther toward the infrared end of the spectrum, because the vibration transition has lower energy. For this reason, heavy water does not absorb red light and thus a large body D 2 O will lack the distinctive blue color of the more commonly found light water ( 1 H 2 O).
The intensity of absorption decreases substantially with each successive tone, resulting in very weak absorption for the third note. For this reason, the pipe must have a length of one meter or more and the water must be purified by microfiltration to remove the particles that can produce Mie scattering.
Maps Color of water
Color of lake and ocean
The lakes and oceans look blue for several reasons. One is the water surface reflects the color of the sky. While this reflection contributes to the observed color, it is not the only reason.
Some light, on the surface of the ocean, is reflected back directly but mostly penetrates the surface of the water that interacts with its molecules. The water molecule can vibrate in three different modes when light strikes. The wavelengths of red, orange, yellow, and green light are absorbed so that the remaining light appears to consist of shorter wavelengths of blues and violets. This is the main reason why the color of the ocean is blue.
Some constituents of sea water can affect the blue color of the oceans. This is why it can look greener or more blue in different areas. The water in the pool (which may also contain various chemicals) with the white-painted side and the bottom will appear as a turquoise blue.
Clear water is blue in the white-tiled pool as well as in the indoor pool where there is no reflecting blue sky. The deeper the pool, the more blue the water.
The resistance of suspended particles also plays an important role in the color of lakes and oceans. Several tens of meters of water will absorb all the light, so without scattering, all bodies of water will appear black. Since most lakes and oceans contain suspended living material and mineral particles, known as colored organic matter (CDOM), light from above is reflected upward. The resistance of the suspended particles will usually give a white color, like with snow, but because the first light passes through many meters of blue liquid, the scattered light looks blue. In very pure water - as found in mountain lakes, where the scattering of the white particles is lost - the scattering of the water molecules themselves also contributes to the blue color.
Another phenomenon that occurs is Rayleigh scattering in the atmosphere along one's line of sight: the horizon is usually a distance of 4-5 km and the air (which is just above sea level in the case of the oceans) is at its densest point. This mechanism will add a blue tinge to a distant object (not just the sea) because the blue light will spread to one's line of sight.
Sea and lake surfaces often reflect the blue sky, making it look more blue. The relative contribution of the reflected skylight and the light scattered back from the depth is highly dependent on the angle of observation.
Glacier color
Glaciers are large bodies of ice and snow that form during very cold climates with processes that involve falling snow compaction. While snowy glaciers appear white from a distance, close up and when sheltered from direct ambient light, glaciers usually appear in blue because of long long roads from internal reflected light.
The relatively small amount of regular ice appears white, because of the many air bubbles that exist, and also because a small amount of water appears colorless. On glaciers, on the other hand, pressure causes air bubbles, trapped in snow accumulation, to squeeze increasing the created ice density. Because large amounts of water look blue then a large piece of ice that is compressed, or glacier, will appear blue.
Water color sample
Solutes and particulates in water can cause discoloration. The color change is slightly measured in units of Hazen (HU). Dirt can be very colorful too, for example dissolved organic compounds called tannins can produce dark brown, or floating algae in water (particles) can give a green color.
The color of the water sample can be reported as:
- Clear colors are the colors of all water samples, and consist of the colors of the dissolved and suspended components.
- Real colors are measured after filtering water samples to remove all suspended material.
Color testing can be a quick and easy test that often reflects the amount of organic material in the water, although certain inorganic components such as iron or manganese can also provide color.
Water color can reveal physical, chemical and bacteriological conditions. In drinking water, green can show copper washing from copper pipes and can also represent algal growth. Blue can also exhibit copper, or it may be caused by industrial cleaning syphoning in a commode tank, commonly known as backflow. Reds may be rust marks from iron pipes or bacteria in the air from the lake, etc. Black water can show the growth of sulfur reducing bacteria in a hot water tank set to too low a temperature. It usually has a strong sulfur or rot odor (H 2 S) and is easily corrected by draining the water heater and raising the temperature to 49 ° C (120 ° F) or higher. The smell will always be in hot water pipes if sulfate reducing bacteria is the cause and never in cold water pipes. Spectrum of colors with broad water indicators and, if studied, can identify and solve cosmetic, bacteriological and chemical problems more easily.
Water quality and color
The presence of color in water does not necessarily indicate that water can not be drunk. Color-causing materials such as tannins may be harmless.
Color is not removed by ordinary water filter; however, slow sand filters can remove color, and the use of coagulants can also successfully capture the color-causing compounds in the resulting sediment.
Other factors can affect visible colors:
- Particles and solutes can absorb light, as in tea or coffee. Green algae in rivers and streams often give a blue-green color. The Red Sea sometimes blooms red Trichodesmium erythraeum algae.
- Particles in water can spread light. The Colorado River is often muddy red from being stung by reddish mud in the water. Some mountain lakes and rivers with finely ground rock, such as glacial flour, are turquoise. The spreading of light by suspended matter is required so that the blue light generated by the water absorption can return to the surface and be observed. Such a spread can also shift the photon spectrum that appears to the green, a color often seen when water loaded with suspended particles is observed.
Name of color
Different cultures divide the semantic fields of different colors from the use of English and some do not distinguish between blue and green in the same way. An example is Welsh where glas can mean blue or green.
Other color names assigned to water bodies are sea-green and navy blue. Unusual ocean colors have caused the term red tide and black waves.
The Ancient Greek Poet, Homer, used the nickname "the dark sea of ​​wine"; In addition, he also describes the sea as "gray". William Ewart Gladstone has suggested that this is because the Ancient Greeks classified colors primarily by luminosity rather than color, while others believed that Homer was color-blind.
References
Further reading
- Dickey, Tommy D.; Kattawar, George W.; Voss, Kenneth J. (April 2011), "Sheds a new light on the ocean's light" (PDF) , Today's Physics , 64 ( 4): 44-49, Bibcode: 2011PhT.... 64d..44D, doi: 10.1063/1.3580492, archived from the original (PDF) in 2012-04-25
- Pettit, Edison (February 1936), "On the Water Color of Crater Lake", Proceedings of the National Academy of Sciences of the United States , 22 (2): 139-146, Bibcode: 1936PNAS... 22..139P, doi: 10.1073/pnas.22.2.139, PMCÃ, 1076722 , PMIDÃ, 16588059 src: image.slidesharecdn.com
External links
- Water Color, School of Water Science USGS
- What color is water?
- blue water color? The absorption spectrum of water in the visible range
- What is clean water?
Source of the article : Wikipedia
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