Question

when the color of the sea changed from grey to Green it indicated​

Answer 1

The "color" of the ocean is determined by the interactions of incident light with substances or particles present in the water. White sunlight consists of a spectrum of wavelengths (about 400–700 nm), which water droplets disperse into a continuous spectrum of "rainbow" colors. Large quantities of water, even in a swimming pool, would appear blue as well.

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