iandol on sun 31 mar 02
Dear Lee Love,
If the bubbles can be seen with the naked eye they cannot cause the =
Rayleigh Effect backscattering effect whish is responsible for the =
separation of the complementary colours of Blue and orange.
To see this effect in an everyday situation find a smoker of cigarettes. =
Stand with your back to the Sun and your smoker in line on the opposite =
side. You will see blue smoke. Now get them to stand between you and the =
sun and look through the smoke. It will look brown. According to =
Rayleigh the Energy scattered by small particles is equal to the inverse =
of the Fourth Power of the Wavelength. In addition, the particles which =
cause the scattering are Molecules, which as we both know have =
dimensions in the Nano metre range not the millimetre range.
Bubbles create opacity by a different process, that of refraction at the =
interface of adjoining materials which are transparent but have =
differing Refractive Indices, causing path of light beams to be bent, =
reflected and defracted. For Air and many gases it is near to 1, for =
silica glasses it varies according to composition, say 1.5 upwards. This =
can be seen with a rainbow due to the differing refractive indices of =
water and air. If you look beyond the colour bands of the Bow you will =
notice that one side is very dark and the other is much lighter.
Interesting to see that Margaret Medley (The Chinese Potter)puts the =
blue colour down to the presence of Iron (p118). She has an illustration =
(Plate 3)which would make your eyes water.
Enjoying our exchange on this topic.
Best regards,
Ivor
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