question: How does standing water have two colors?
comment: In most of the puddle you are seeing light scattered from small particles of silt and clay. On the edges there isn’t enough water depth to do much scattering so you see the darker bottom. As the puddle settles the edge should grow. The edge colour varies according to the type of dirt. More organic matter = darker edge. You can get more than two colours. If puddle reflects sky you get sky colours. Blue or various cloud colours. You may get green from trees.
passages: Pink water is actually colorless at the time of generation, whereas red water can be colorless or a very pale red. The color is produced by photolytic reactions under the influence of sunlight. Despite the names, red and pink water are not necessarily different shades; the colour depends mainly on duration of solar exposure. If exposed long enough, "pink" water will become dark brown.
   Section::::Plot.
   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.
   The intrinsic colour of liquid water may be demonstrated by looking at a white light source through a long pipe that is filled with purified water and closed at both ends with a transparent window. The light turquoise blue colour is caused by weak absorption in the red part of the visible spectrum.
   Color of water
  
  The color of water varies with the ambient conditions in which that water is present. While relatively small quantities of water appear to be colorless, pure water has a slight blue color that becomes a deeper blue as the thickness of the observed sample increases. The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light. Dissolved elements or suspended impurities may give water a different color.
  
  Section::::Intrinsic colour.
   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.
   BULLET::::- Particles and solutes can absorb light, as in tea or coffee. Green algae in rivers and streams often lend a blue-green color. The Red Sea has occasional blooms of red "Trichodesmium erythraeum" algae.
   BULLET::::- Mousseline: Mousseline is Cello's best friend. She is a sophomore palette, as she passed in the year Cello failed. She is often seen with her partner, a yellow round parrot-like bird named Kechonpa. The English edition has a translation discrepancy with her name, as it has been seen as Mousseline, Mosseline, and Mosslyn.
   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.
   Testing for color can be a quick and easy test which often reflects the amount of organic material in the water, although certain inorganic components like iron or manganese can also impart color.
   The shades of blue, turquoise, and green are slightly iridescent, and can appear to change colour with different lighting conditions or viewing angles; this is because these colours (unlike black or red) are not due to pigments, but created through refraction within a layer of translucent guanine crystals. Breeders have also developed different colour patterns such as marble and butterfly, as well as metallic shades through hybridization like copper, gold, or platinum (these were obtained by crossing "B. splendens" to other "Betta" species).
   Section::::Sources of metamerism.
  
  Metameric matches are quite common, especially in near neutral (grayed or whitish colors) or dark colors. As colors become brighter or more saturated, the range of possible metameric matches (different combinations of light wavelengths) becomes smaller, especially in colors from surface reflectance spectra.
  
  Metameric matches made between two light sources provide the trichromatic basis of colorimetry. For any given light stimulus, regardless of the form of its spectral emittance curve, there always exists a unique mixture of three "primary" lights that when added together, or added to the stimulus, will be an exact metameric match.
   For breeding, these tetras need water similar to the waters in which they live in the wild; extremely soft water with a pH of about 6 and a temperature of around . Ideally, the water should be highly stained by the tannins from peat, in subdued light, shaded by plants. It spawns in a school, although in the actual act of spawning, one female may be closely associated with one or more males.
   Section::::Pigmentation.
  
  Many species are highly pigmented, e.g. the blue "Stentor coeruleus". In "Blepharisma", the red pigment is associated with light sensitivity. Species of blue-pigmented "Eufolliculina" form extensive mats in the deep sea that have been called "blue mats".
  
  Section::::Systematics.
   In water, light attenuates for each wavelength, differently. The UV, violet ( 420 nm), and red (< 500 nm) wavelengths disappear before blue light (470 nm), which penetrates clear water the deepest. The wavelength composition is constant for each depth and is almost independent of time of the day and the weather. To gauge depth, an animal would need two photopigments sensitive to different wavelengths to compare different ranges of the spectrum. Such pigments may be expressed in different structures.
   The different colours are a result of the different charged states of the dye molecule. In the yellow form, all three nitrogen atoms carry a positive charge, of which two are protonated, while the green colour corresponds to a form of the dye with two of the nitrogen atoms positively charged. At neutral pH, both extra protons are lost to the solution, leaving only one of the nitrogen atoms positive charged. The p"K" for the loss of the two protons are approximately 1.15 and 1.8.
   Section::::Individual efforts.
   Dissolved and particulate material in water can cause discoloration. Slight discoloration is measured in Hazen units (HU). Impurities can be deeply colored as well, for instance dissolved organic compounds called tannins can result in dark brown colors, or algae floating in the water (particles) can impart a green color.
  
  The color of a water sample can be reported as:
  
  BULLET::::- "Apparent color" is the color of the whole water sample, and consists of color from both dissolved and suspended components.
  
  BULLET::::- "True color" is measured after filtering the water sample to remove all suspended material.
   Section::::Mechanism.
   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.
   Many external factors can influence colour: light, temperature, pH, sugars and metals. There is a method to turn petunia flowers from white to transparent. The petunia flower is immersed into a flask of water, connected to a vacuum pump, after which the flower appeared colourless. The white colour is expressed by the air present in the vacuoles that absorb the light, without air the flower loses the white colour.
   Section::::Rebounding.
   Emulsions contain both a dispersed and a continuous phase, with the boundary between the phases called the "interface". Emulsions tend to have a cloudy appearance because the many phase interfaces scatter light as it passes through the emulsion. Emulsions appear white when all light is scattered equally. If the emulsion is dilute enough, higher-frequency (low-wavelength) light will be scattered more, and the emulsion will appear bluer – this is called the "Tyndall effect". If the emulsion is concentrated enough, the color will be distorted toward comparatively longer wavelengths, and will appear more yellow. This phenomenon is easily observable when comparing skimmed milk, which contains little fat, to cream, which contains a much higher concentration of milk fat. One example would be a mixture of water and oil.
   The red-pigmented species "P. rubescens" is regularly found in clear, deep alpine and pre-alpine lakes that are seasonally stratified. Outbreaks of "P. rubescens" are known as the "Burgundy-blood phenomenon." It grows at depth, in the low light conditions of the metalimnion, where it can maximize the absorption of green light with its phycoerythrin pigments. Under the action of wind-induced internal waves, "P. rubescens" can be moved vertically by several meters following the movements of the metalimnion, which in turn modifies rapidly (within a day) the light conditions experienced by the filaments. This was shown to significantly affect the photosynthesis rate and oxygen production, especially in lakes where the dominant organism of the phytoplankton community is "P. rubescens", such as in Lake Zurich.
   HABs from cyanobacteria (blue-green algae) can appear as a foam, scum, or mat on or just below the surface of water and can take on various colors depending on their pigments. Cyanobacteria blooms in freshwater lakes or rivers may appear bright green, often with surface streaks which looks like floating paint. Similarly, red tides made up of dinoflagellates, also contain photosynthetic pigments that vary in color from green to brown to red.
  
raw_presuppositions: Standing wanter has two colors.
raw_corrections: Water is colored based on how it is reflecting light and what is in the water. There can be more than 2 colors. 