Why ‘sea’ is blue?

Rayleigh, a physicist proposed that sea appears blue because, the blue sky above the sea reflects in sea water.

Our Indian physicist sir. C.V Raman differed with this theory because; the blue of sea is more intense than that of the sky. The color of reflected light cannot be more intense than that of the source.

In order to find the reason for the ‘sea’ to be blue Raman, has experimented on the behaviour of light when it incidents on a number of liquids.

While light emitted from the sun when it passes through a glass prism splits into seven of its constituent colors, violet, Indigo, Blue, Green, Yellow, orange and Red (VIBGYOR). This process is called ‘Dispersion’.

Light which is having wave nature with different wavelengths for different colors, the wavelength of ‘violet’ is minimum and that of red is maximum.

Raman proposed that the sun light when it incidents on seawater, the rays get irregular reflections and the phenomenon is called scattering, (just as small glass beads move in various directions when thrown on a hand floor when thrown from a height). Raman further argued that when sun light incidents on seawater, the blue color with lesser wavelength scatters more than that of other colors and reaches our eye and thus the color of sea appears to be blue. This great invention is called ‘Raman effect’ for which sir C.V Raman was awarded the ‘Nobel prize’ in physics, incidentally, Raman was not only the first Indian, but also the first Asian to be awarded the first Nobel Prize in physics.

Certain times ‘sea’ appears to be ‘green’ in color. The reason for this is the presence of Bio-chemical substances in certain stones and plants in the sea.

These objects absorb the violet and blue colors in the incident sunlight and emits the green color only. This phenomenon is called ‘Fluorescence’. This fact was discovered by our Indian physicist Prof. K.R. Ramanathan.

Prof. Laxmi… Emani

Published date : 21 Feb 2013 02:36PM