question: How come if water is clear, snow is white?
comment: What if I told you snow is not white? But the light passing through it is obscured. Same idea behind glass being clear normally but if you tried to look through a bunch of crushed glass you'd have a bad time. The crystals formed in snow prevent light from passing as clearly and make the snow appear "white"
passages: BULLET::::7. "Based, as we said, on the quantity and constitution of the underlying objects, meaning generally by "constitution" the manner of composition." So, for example, goat horn appears black when intact and appears white when ground up. Snow appears white when frozen and translucent as a liquid.
   Section::::Formation.:Appearance.
  
  Section::::Formation.:Appearance.:Color.
  
  Although ice by itself is clear, snow usually appears white in color due to diffuse reflection of the whole spectrum of light by the scattering of light by the small crystal facets of the snowflakes of which it is comprised.
  
  Section::::Formation.:Appearance.:Shape.
   Relatively small amounts of regular ice appear white because plenty of air bubbles are present, and also because small quantities of water appear to be colorless. In glaciers, on the other hand, the pressure causes the air bubbles, trapped in the accumulated snow, to be squeezed out increasing the density of the created ice. Large quantities of water appear blue, therefore a large piece of compressed ice, or a glacier, would also appear blue.
  
  Section::::Color of water samples.
   Section::::Color of glaciers.
  
  Glaciers are large bodies of ice and snow formed in cold climates by processes involving the compaction of fallen snow. While snowy glaciers appear white from a distance, up close and when shielded from direct ambient light, glaciers usually appear a deep blue due to the long path lengths of the internal reflected light.
   Note that white caps on waves look white (and have high albedo) because the water is foamed up, so there are many superimposed bubble surfaces which reflect, adding up their reflectivities. Fresh 'black' ice exhibits Fresnel reflection.
  
  Snow on top of this sea ice increases the albedo to 0.9.
  
  Section::::Examples of terrestrial albedo effects.:Clouds.
   In the case of glaciers, the ice is more tightly pressed together and contains little air. As sunlight enters the ice, more light of the red spectrum is absorbed, so the light scattered will be bluish.
   If one were to imagine that the figure represents snow, and that the polygons are its (transparent) ice crystallites, an impinging ray is partially reflected (a few percent) by the first particle, enters in it, is again reflected by the interface with the second particle, enters in it, impinges on the third, and so on, generating a series of "primary" scattered rays in random directions, which, in turn, through the same mechanism, generate a large number of "secondary" scattered rays, which generate "tertiary" rays, and so forth. All these rays walk through the snow crystallites, which do not absorb light, until they arrive at the surface and exit in random directions. The result is that the light that was sent out is returned in all directions, so that snow is white despite being made of transparent material (ice crystals).
   BULLET::::7. "Based, as we said, on the quantity and constitution of the underlying objects, meaning generally by "constitution" the manner of composition." So, for example, goat horn appears black when intact and appears white when ground up. Snow appears white when frozen and translucent as a liquid.
   On the surface of lakes, or other bodies of still freshwater, "congelation ice" is often called "black Ice". This ice has frozen without many air bubbles trapped inside, making it transparent. Its transparency reveals the colour, usually black, of the water beneath it, hence the name. This is in contrast to "snow ice", sometimes called "slush ice", which is formed when slush (water saturated snow) refreezes. Snow ice is white due to the presence of air bubbles.
   Commonly seen white icebergs generally derive their color from the snow and frost remaining on the surface which results in the uniform reflection of incident light. Young glaciers that have not undergone years of compression, may also appear white. Due to the age of the iceberg, there remains a tremendous amount of air and reflective surfaces. The iceberg easily reflects the sun as white light.
  
  BULLET::::- Preferential light absorption and age
   Compaction of snow reduces the penetration of long- and short-wave radiation by reflecting more radiation off the snow. This limitation of light transmission through the snowpack decreases light availability under the snow. Only 3% of light can penetrate to a depth of 20 cm of snow when the density is 0.21 g/cm. At a depth of 40 cm, less than 0.2% of light is transmitted from the snow surface to ground below. This decrease in light transmission occurs up to the point at which critical compaction is reached. This occurs because the surface area of the ice crystal decreases and it causes less refraction and scattering of light. Once densities reach 0.5 g/cm, total surface area is reduced, which in turn reduces internal refraction and allows light to penetrate deeper into the snowpack.
   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.
   Other colors can appear in the presence of light absorbing impurities, where the impurity is dictating the color rather than the ice itself. For instance, icebergs containing impurities (e.g., sediments, algae, air bubbles) can appear brown, grey or green.
  
  Section::::Physical properties.:Phases.
  
  Ice may be any one of the 18 known solid crystalline phases of water, or in an amorphous solid state at various densities.
   Snow is a mixture of air and tiny ice crystals. When white sunlight enters snow, very little of the spectrum is absorbed; almost all of the light is reflected or scattered by the air and water molecules, so the snow appears to be the color of sunlight, white. Sometimes the light bounces around inside the ice crystals before being scattered, making the snow seem to sparkle.
   BULLET::::- Opaque objects that do not reflect specularly (which tend to have rough surfaces) have their color determined by which wavelengths of light they scatter strongly (with the light that is not scattered being absorbed). If objects scatter all wavelengths with roughly equal strength, they appear white. If they absorb all wavelengths, they appear black.
   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".
   As White as in Snow
  
  As White as in Snow (Swedish title: "Så vit som en snö") is a Swedish film which was released to cinemas in Sweden on 16 February 2001, directed by Jan Troell. It won three Guldbagge Awards, for best film, best direction and best cinematography, and was nominated for best screenplay.
   Whiteout (weather)
  
  Whiteout is a weather condition in which visibility and contrast are severely reduced by snow, fog, or sand. The horizon disappears from view while the sky and landscape appear featureless, leaving no points of visual reference by which to navigate. Whiteout has been defined as: "A condition of diffuse light when no shadows are cast, due to a continuous white cloud layer appearing to merge with the white snow surface. No surface irregularities of the snow are visible, but a dark object may be clearly seen. There is no visible horizon."
   The spectrum of ice is similar to that of liquid water, with peak maxima at 3400 cm (2.941 μm), 3220 cm (3.105 μm) and 1620 cm (6.17 μm)
  
  Section::::Visible region.
   Many mountains with winter or year-round snow cover are named accordingly: Mauna Kea means "white mountain" in Hawaiian, Mont Blanc means "white mountain" in French. Changbai Mountains literally meaning "perpetually white mountains", marks the border between China and Korea.
  
  Section::::Scientific understanding (Color science).:Why snow, clouds and beaches are white.:White materials.
   BULLET::::- Objects that [[Transparency and translucency|transmit light]] are either "translucent" (scattering the transmitted light) or "transparent" (not scattering the transmitted light). If they also absorb (or reflect) light of various wavelengths differentially, they appear tinted with a color determined by the nature of that absorption (or that reflectance).
   Color constancy is achieved by chromatic adaptation. The International Commission on Illumination defines "white (adapted)" as "a color stimulus that an observer who is [chromatically] adapted to the viewing environment would judge to be perfectly achromatic and to have a luminance factor of unity. The color stimulus that is considered to be the adapted white may be different at different locations within a scene.
  
  Section::::Scientific understanding (Color science).:Why snow, clouds and beaches are white.
   Small amounts of regular ice appear to be white because of air bubbles inside them and also because small quantities of water appear to be colourless. In glaciers, the pressure causes the air bubbles to be squeezed out, increasing the density of the created ice. Large quantities of water appear to be blue, as it absorbs other colours more efficiently than blue. A large piece of compressed ice, or a glacier, similarly appears blue.
   BULLET::::- Particles in water can scatter light. The Colorado River is often muddy red because of suspended reddish silt in the water. Some mountain lakes and streams with finely ground rock, such as glacial flour, are turquoise. Light scattering by suspended matter is required in order that the blue light produced by water's absorption can return to the surface and be observed. Such scattering can also shift the spectrum of the emerging photons toward the green, a color often seen when water laden with suspended particles is observed.
  
  Section::::Color names.
   Section::::Limitations.
  
  Although the equation is very general, it does not capture every aspect of light reflection. Some missing aspects include the following:
  
  BULLET::::- Transmission, which occurs when light is transmitted through the surface, such as when it hits a glass object or a water surface,
  
  BULLET::::- Subsurface scattering, where the spatial locations for incoming and departing light are different. Surfaces rendered without accounting for subsurface scattering may appear unnaturally opaque — however, it is not necessary to account for this if transmission is included in the equation, since that will effectively include also light scattered under the surface,
  
presuppositions: Snow is white. Snow is actually white.
corrections: Snow is not white as the crystals formed in snow prevent light from passing as clearly making the snow appear "white". Snow appears white because it prevents light passing through it clearly.
raw_presuppositions: Snow is white. Snow is actually white.
raw_corrections: Snow is not white as the crystals formed in snow prevent light from passing as clearly making the snow appear "white". Snow appears white because it prevents light passing through it clearly.