question: Why is gasoline rainbow on pavement?
comment: The thickness of the gasoline is close to the wavelengths of visible light. Light reflects off of the surface of the gas/air border as well as the gas/water border. The two reflections can mix in two ways. At a given thickness, some colors are attenuated due to destructive interference, while others are enhanced by constructive interference.
passages: BULLET::::- Two kerosene oil storage buildings — if one had caught fire, there was a secondary source
   Originally created in 1971, the Rainbow Swash comprises large streaks of rainbow colors over a natural gas storage tank on Dorchester's waterfront, located about two miles (3 km) south of Downtown Boston. The landmark design is highly visible from the Southeast Expressway and passed by hundreds of thousands of commuters daily. The design was transferred to its present location in 1992
  
  when the original LNG tank was torn down.
  
  Section::::History.
   Tungsten-halogen lamps are a very common light source for headlamps and other forward illumination functions. Some recent vehicles use small halogen bulbs for exterior signalling and marking functions, as well. The first halogen lamp approved for automotive use was the H1, which was introduced in Europe in 1962, 55 W producing 1500 lm.
  
  Section::::Light sources.:Light-emitting diodes (LED).
   Section::::History.
   Neon tubes that are used for the underglow of a car start of heating it up to high temperatures. From there they are filled with neon gas. Though neon gas only produces the color red, adding other elemental gases could change the tube up to 150 colors. Mercury makes blue, carbon dioxide makes white, helium makes gold, and phosphorus creates different colors under various pressures. Because neon tubes are gas compressed, they tend to break often while going over speed bumps. With the neon tubes, people are more able to adjust them to follow specific rhythms like music.
   BULLET::::- Shading and dirt
   BULLET::::1. Reflection of star lights
  
  BULLET::::2. Luminous jellyfish
  
  BULLET::::3. Fire from undersea active volcano
  
  BULLET::::4. Light of fishing boats
   Section::::1990s.
   Almost everything on Earth contains elements of water; oil and fuel are no exceptions. While very small amounts exist in fuels to start with, stored fuel will become a breeding ground for the microbial bacteria and over time, the levels of damage change from dissolved to emulsified and finally free.
  
  BULLET::::- Dissolved - Dissolved water in oil is the presence of water but, unnoticeable to the eye. The water continues to develop until saturation point where water visibility begins.
   When Dorothy Gale, her pet dog Toto, the Shaggy Man, and Button-Bright first encounter Polychrome in the fifth chapter of "The Road to Oz", she is seen dancing to keep herself warm, after accidentally sliding off her father's rainbow and landing on the surface of the Earth. (Her father withdrew his bow without realizing she had been left behind.) Polychrome is described as:
   The music video for the song features the band performing in a darkened space and a girl in her bedroom surrounded by fashion magazines and cosmetics. As the video progresses, the girl is shown using the cosmetics in an attempt to cover words that are scrawled on her face such as "liar" and "hypocrite". As the song reaches the bridge and final chorus, it is revealed that the band had been performing behind the mirror as singer Shaun Morgan busts through it, knocking over a candle and setting fire to her magazines.
   Section::::Banding and ribbons.
   photopic eye. Predominantly because of this effect, white light sources such as metal halide, fluorescent, or white LED can produce as much as 3.3 times the visual sky glow brightness of the currently most-common high-pressure sodium lamp, and up to eight times the brightness of low-pressure sodium or amber Aluminium gallium indium phosphide LED.
   Section::::Geographic Distribution.
   Section::::1980s.
   Section::::Light sources.:High intensity discharge (HID).
  
  High-intensity discharge, or HID lamps, sometimes referred to as "xenon lamps" are modified metal halide lamps employing xenon fill gas. Traditional HID lamps such as those used for general lighting have a long warm-up time. Headlamps must provide light very shortly after they are turned on, and xenon gas serves to reduce start-up time.
  
  Section::::Light sources.:Neon tubes.
   In 1971, then–Boston Gas Company president Eli Goldston commissioned Corita Kent to paint the Rainbow Swash design on one of two adjacent LNG tanks facing Boston's Southeast Expressway. The original design was painted on an 8-inch (20 cm) scale model, from which 20 painters reproduced the work on the high tank.
   Section::::Modern lights.
   These effects combine to yield the remarkable sight of a green spot running around in a circle on a grey background when only stationary, flashing grey spots have been presented.
  
  Section::::Psychophysics.
   On vehicles equipped with OBD-II, the light has two stages: it illuminates steadily to indicate a minor fault such as a loose gas cap or malfunction with the vehicle's emissions controls, and it flashes repeatedly when a severe misfire is detected to alert the driver the potential of severe engines or catalyst damages.
  
  The MIL can present a legend, such as , , , or ; or it also can present a pictogram of an engine.
   Section::::Ecology.
   Rainbows can be caused by many forms of airborne water. These include not only rain, but also mist, spray, and airborne dew.
  
  Section::::Visibility.
   Section::::Welsbach lights.
   Though gasoline is a naturally colorless liquid, many gasolines are dyed in various colors to indicate their composition and acceptable uses. In Australia, the lowest grade of gasoline (RON 91) was dyed a light shade of red/orange and is now the same colour as the medium grade (RON 95) and high octane (RON 98) which are dyed yellow. In the United States, aviation gasoline (avgas) is dyed to identify its octane rating and to distinguish it from kerosene-based jet fuel, which is clear. In Canada, the gasoline for marine and farm use is dyed red and is not subject to sales tax.
   BULLET::::- Astoria, Oregon, has a community program for restoring vault lights, funded by the Astoria Downtown Historic District Association. A volunteer plan to replace broken glass with squares of Lexan, topped with resin embedded with glass teardrops, was prevented by legislation.
  