question: Why is the ocean blue while it's water is clear if out of the ocean?
comment: Scattering of water out of the ocean. Bluer lights are scattered more than redder lights. The deeper it is, the more this effect is apparent.
passages: The "color" of the ocean is determined by the interactions of incident light with substances or particles present in the water. White light from the sun is made up of a combination of colors that are broken apart by water droplets in a "rainbow" spectrum. Large quantities of water, even in a swimming pool, would appear blue as well. When light hits the water surface, the different colors are absorbed, transmitted, scattered, or reflected in differing intensities by water molecules and other so-called optically-active constituents in suspension in the upper layer of the ocean. The reason that open ocean waters often appear blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the scattering of blue light in the sky but absorption is a much larger factor than scattering for the clear ocean water. In water, absorption is strong in the red and weak in the blue and so red light is absorbed quickly in the ocean leaving blue. Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. When sunlight hits the ocean, some of the light is reflected back directly, but most of it penetrates the ocean surface and interacts with the water molecules that it encounters. The red, orange, yellow, and green wavelengths of light are absorbed and so the remaining light we see is composed of the shorter wavelength blues and violets.
   The sea is seen as blue for largely the same reason: the water absorbs the longer wavelengths of red and reflects and scatters the blue, which comes to the eye of the viewer. The colour of the sea is also affected by the colour of the sky, reflected by particles in the water; and by algae and plant life in the water, which can make it look green; or by sediment, which can make it look brown.
  
  Section::::Science and nature.:Atmospheric perspective.
   In clear open waters, visible light is absorbed at the longest wavelengths first. Thus, red, orange, and yellow wavelengths are absorbed at higher water depths, and blue and violet wavelengths reach the deepest in the water column. Because the blue and violet wavelengths are absorbed last compared to the other wavelengths, open ocean waters appear deep-blue to the eye.
   Some constituents of sea water can influence the shade of blue of the ocean. This is why it can look greener or bluer in different areas. Water in swimming pools (which may also contain various chemicals) with white-painted sides and bottom will appear as a turquoise blue.
  
  Clean or uncontaminated water appears blue in white-tiled swimming pools as well as in indoor pools where there is no blue sky to be reflected. The deeper the pool, the bluer the water.
   Absorption intensity decreases markedly with each successive overtone, resulting in very weak absorption for the third overtone. For this reason, the pipe needs to have a length of a meter or more and the water must be purified by microfiltration to remove any particles that could produce Mie scattering.
  
  Section::::Color of lakes and oceans.
  
  Lakes and oceans appear blue for several reasons. One is that the surface of the water reflects the color of the sky. While this reflection contributes to the observed color, it is not the sole reason.
   Section::::History.
   The most important light-absorbing substance in the oceans is chlorophyll, which phytoplankton use to produce carbon by photosynthesis. Chlorophyll, a green pigment, makes phytoplankton preferentially absorb the red and blue portions of the light spectrum and reflect green light. Ocean regions with high concentrations of phytoplankton have shades of blue-green depending upon the type and density of the phytoplankton population there. The basic principle behind the remote sensing of ocean color from space is that the more phytoplankton is in the water, the greener it is.
   Section::::Background.
   BULLET::::- Color spectrum and water
  
  Light is absorbed and reflected in water. Visible white light is made up of a spectrum of colors from the rainbow, ranging from red to violet. As the light travels through the water, the waves of light from the red end of the spectrum dissipate (i.e. are absorbed), while those from the blue end, become more prominent.
  
  Section::::RMS "Titanic".
   The colors below are arranged according to value (brightness) (the v code in hsv), lightest at the top and darkest towards the bottom.
  
  Section::::Variations of blue-gray.:Iceberg.
  
  The color iceberg is displayed at right.
  
  Although icebergs are white, from a distance they can often appear blue when the colors of the sky and the ocean are reflected off of them.
  
  The first recorded use of "iceberg" as a color name in English was in 1921.
  
  Section::::Variations of blue-gray.:Slate blue.
  
  Displayed at right is the web color slate blue.
   In near-shore (coastal) waters, sea water contains more phytoplankton than the very clear central ocean waters. Chlorophyll-a pigments in the phytoplankton absorb light, and the plants themselves scatter light, making coastal waters less clear than open waters. Chlorophyll-a absorbs light most strongly in the shortest wavelengths (blue and violet) of the visible spectrum. In near-shore waters where there are high concentrations of phytoplankton, the green wavelength reaches the deepest in the water column and the color of water to an observer appears green-blue or green.
  
  Section::::Seismic waves.
   Section::::Composition.
   Various cultures divide the semantic field of colors differently from the English language usage 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 bodies of water are sea green and ultramarine blue. Unusual oceanic colorings have given rise to the terms red tide and black tide.
   Scattering from suspended particles also plays 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 most lakes 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 white color, as with snow, but because the light first passes through many meters of blue-colored liquid, the scattered light appears blue. In extremely pure water—as is found in mountain lakes, where scattering from white-colored particles is missing—the scattering from water molecules themselves also contributes a blue color.
   The bluish ocean color is a composite of several contributing agents. Prominent contributors include dissolved organic matter and chlorophyll. Mariners and other seafarers have reported that the ocean often emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow. It is most likely caused by bioluminescence.
  
  Section::::Earth's global ocean.:Oceanic zones.
   Section::::Sedimentation and blue carbon burial.:Spatial variability in sedimentation.:Submarine Canyons.
   Section::::Death and legacy.
   There are other substances that may be found dissolved in the water that can also absorb light. Since the substances are usually composed of organic carbon, researchers generally refer to them as colored dissolved organic matter.
  
  Section::::Ocean color radiometry.
   Section::::Attributes of a blue-water navy.:Overseas basing.
   Water preferentially absorbs red light, and to a lesser extent, yellow, green and violet light, so the color that is least absorbed by water is blue light. Particulates and dissolved materials may absorb different frequencies, and this will affect the color at depth, with results such as the typically green color in many coastal waters, and the dark red-brown color of many freshwater rivers and lakes due to dissolved organic matter.
   A. For murky, turbid water of low visibility (rivers, harbors, etc.)
  
  B. For moderately turbid water (sounds, bays, coastal water).
  
  C. For clear water (southern water, deep water offshore, etc.).
  
  The most difficult colors at the limits of visibility with a water background are dark colors such as gray or black.
  
  Section::::Color vision.:Physiological variations.
   Section::::Recordings by other artists.
   Section::::Color vision.
  
  Water attenuates light due to absorption which varies as a function of frequency. In other words, as light passes through a greater distance of water color is selectively absorbed by the water. Color absorption is also affected by turbidity of the water and dissolved material.
   Section::::Fluorescence in nature.:Aquatic biofluorescence.:Photic zone.
  
  Section::::Fluorescence in nature.:Aquatic biofluorescence.:Photic zone.:Fish.
  
  Bony fishes living in shallow water generally have good color vision due to their living in a colorful environment. Thus, in shallow-water fishes, red, orange, and green fluorescence most likely serves as a means of communication with conspecifics, especially given the great phenotypic variance of the phenomenon.
   Section::::Concept.:Blue ocean vs. red ocean.
  
presuppositions: The ocean should be clear since water is clear.
corrections: The ocean is blue due to scattering of water out of the ocean.
raw_presuppositions: The ocean should be clear since water is clear. The ocean should be clear since water is clear.
raw_corrections: The ocean is blue due to scattering of water out of the ocean. The ocean is blue due to scattering of water out of the ocean.