Scattering of light

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Scatterimg of light

Why the color of ocean is blue? If you are thinking that the color of ocean is blue due to the reflection of sky... then you are having a misconception. The color of ocean is blue due to the scattering of blur color by water molecules. We already know that light is made up of seven colors that are violet, indigo, blue, green, yellow, orange and red. Every color has different wavelength. The color with shorter wavelength, bends more where the color with higher wavelength, bends less. Violet bends more than red because of shorter wavelength. The size of the water molecules are very small (smaller than colloidal particles) and small size particle scatters the color of lower wavelength more. Hence the color of ocean is blue. This is the same reason for the blue color appearance of sky.

Now you must be thinking that violet has shorter wavelength than blue. Then why we are seeing blue color of ocean and sky rather than violet? The answer is... the sunlight has more blue compare to violet color component and our eyes are more sensible to blue than violet. Because our eyes has cones which are more sensitive towards blue.

Why the sky appears reddish during early morning and evening? In the early morning, the sunlight travels larger distance compare to at noon to reach the earth surface. The earth atmosphere is consist of different gases like oxygen, nitrogen, carbon dioxide, etc. These molecules of gases are very small. During early morning and evening, the shorter wavelength like blue are already scattered by the gases present in the earth atmosphere and hence the only color which can be visible is longer wavelength color like orange and red. Hence, the sky appears reddish during early morning and evening.

How will the sky appear in absence of atmosphere? The sky will appear dark( blue-black color) in the absence of atmosphere, because there will be nothing for scattering of sunlight.