>> URI: only with air... with oil it is the extreme thinness of the surface film that causes the optical interference.
That’s an excellent book on the subject. I have been getting lots of National Academy of Science material for years. People in the underdeveloped world get the material free. One of many “privileges” of being underdeveloped.
Well, I still remember my lesson on optics and they said that when one beam or light (or any radiation for that matter) passes from one medium to another of different density, it diffracts in an angle that is a function of the respective densities of each media and the wavelength of the radiation. The familiar example is the apparently broken stick we see when a stick is immersed in water. We have the impression that the stick has broken forward. It is also the physical phenomenon that rules the properties of lenses to “curve” light beams and make them converge onto one focus.
You see, when a light beam coming from above hits the oily surface, the first thing that happens is “reflection”, that is, it bounces from the surface at the same angle it fell on the surface. As the oily surface is not a pure mirror surface, only a small part of the incoming light is reflected. The rest keeps going, but when entering the microscopic oily layer it is refracted to a new angle.
When this newly refracted light beam hits the water layer, it is refracted again but, this time part of the beam is reflected with the same angle (as before) and re-enters the oily surface in his way up suffering a new refraction. Remember that refraction occurs when there is a passage from layers of different density, as air-water, air-crystal, air-diamond, diamond-water, oil-water, cold air-warm air, crystals of different densities and properties (as in photo lenses), etc.
So, this reflected-refracted light beam exits the oily layer and is then refracted again when entering the air layer. The sequence is this: the incoming beam is refracted-reflected-refracted—refracted. What complicates the whole thing is that when the light beam is reflected from the water it is again reflected by the underside of the oily layer and sent back to the water –that reflects it again. This process is repeated until the light is completely absorbed by the water and the oil.
All these beams that are refracted and reflected and re-refracted and re-reflected in such microscopic distances interfere with each other and the optical interference is formed, creating those beautiful iridescent effects.
The same principle is applied in crystallography and metallurgy for microscopic analyses for structural strength. No rocket science. Just optics, but a tricky part of optics.
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Valich: no one denies there has been a warming trend since 1880. It is the continuation of a warming trend resulting from the recovery of the Little ice Age. We are returning to the warmer days of the medieval Warm period.
The increase since 1880 has been measured as 0,6º C. No big deal. During the Darnsgaard-Oeschger warming events of not so long ago (11,000 years ago, 22,000 ybp, etc) warming happened in just a few DECADES, and the warming was of several degress, not tenths of degrees. And then the temperature went down abruptly, as during the Older and Younger Dryas events, that also were Abrupt Climatic Changes. Of course, they were natural events. So, why do you find so strange that the temperature went up 0.6º C in 130 years?
Tell me now, what's so strange about a climate change. Don't tell me you believe that the climate must (or should) be stable. Tell me when in Earth's climatic history there has been a stable period? Can you?
That’s an excellent book on the subject. I have been getting lots of National Academy of Science material for years. People in the underdeveloped world get the material free. One of many “privileges” of being underdeveloped.
Well, I still remember my lesson on optics and they said that when one beam or light (or any radiation for that matter) passes from one medium to another of different density, it diffracts in an angle that is a function of the respective densities of each media and the wavelength of the radiation. The familiar example is the apparently broken stick we see when a stick is immersed in water. We have the impression that the stick has broken forward. It is also the physical phenomenon that rules the properties of lenses to “curve” light beams and make them converge onto one focus.
You see, when a light beam coming from above hits the oily surface, the first thing that happens is “reflection”, that is, it bounces from the surface at the same angle it fell on the surface. As the oily surface is not a pure mirror surface, only a small part of the incoming light is reflected. The rest keeps going, but when entering the microscopic oily layer it is refracted to a new angle.
When this newly refracted light beam hits the water layer, it is refracted again but, this time part of the beam is reflected with the same angle (as before) and re-enters the oily surface in his way up suffering a new refraction. Remember that refraction occurs when there is a passage from layers of different density, as air-water, air-crystal, air-diamond, diamond-water, oil-water, cold air-warm air, crystals of different densities and properties (as in photo lenses), etc.
So, this reflected-refracted light beam exits the oily layer and is then refracted again when entering the air layer. The sequence is this: the incoming beam is refracted-reflected-refracted—refracted. What complicates the whole thing is that when the light beam is reflected from the water it is again reflected by the underside of the oily layer and sent back to the water –that reflects it again. This process is repeated until the light is completely absorbed by the water and the oil.
All these beams that are refracted and reflected and re-refracted and re-reflected in such microscopic distances interfere with each other and the optical interference is formed, creating those beautiful iridescent effects.
The same principle is applied in crystallography and metallurgy for microscopic analyses for structural strength. No rocket science. Just optics, but a tricky part of optics.
-------------
Valich: no one denies there has been a warming trend since 1880. It is the continuation of a warming trend resulting from the recovery of the Little ice Age. We are returning to the warmer days of the medieval Warm period.
The increase since 1880 has been measured as 0,6º C. No big deal. During the Darnsgaard-Oeschger warming events of not so long ago (11,000 years ago, 22,000 ybp, etc) warming happened in just a few DECADES, and the warming was of several degress, not tenths of degrees. And then the temperature went down abruptly, as during the Older and Younger Dryas events, that also were Abrupt Climatic Changes. Of course, they were natural events. So, why do you find so strange that the temperature went up 0.6º C in 130 years?
Tell me now, what's so strange about a climate change. Don't tell me you believe that the climate must (or should) be stable. Tell me when in Earth's climatic history there has been a stable period? Can you?
