Why does sea water look blue ? Know some scientific reasons.
Why does sea water look blue ?
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| (Blue water in the Sea) |
Small amounts of water look colorless and large amounts of water are also colorless and clean, as water is always colorless but there are some reasons why large amounts of water look blue such as lakes, seas and swimming pools. We all know that there is no color of water but still the water of sea, lake and swimming pool looks blue. Why does this happen ? Let's come to know some scientific reasons behind it.
Actually, the color of pure water is very slightly blue, therefore, it looks blue when we increase its thickness and volume. So, this is the reason why swimming pool water and sea water look blue.
Now, coming to the 2nd reason, we know that water has no color and it is clean but when a light falls on it, it reflects that light easily. So, we can say that blue color of sea is also due to reflection of sky, since sky is blue.
Now, another reason is very interesting and this is the main reason. We all know that sunlight is a mixture of 7 different colors. These are violet, indigo, blue, green, yellow, orange and red (in short form VIBGYOR), where the wavelength of light decreases from red to violet. So the red light has the longest wavelength while the violet has the shortest wavelength. And we should also know that the color of light is divided into two parts, where one is the red part of the light spectrum ( red, orange, yellow and green are longer wavelength light, which come under the red part of the light spectrum) and another is the blue part of the light spectrum (blue, Indigo and violet are shorter wavelength light, which come under the blue part of the light spectrum). When light falls on the ocean, the water molecules absorb the red part of the light spectrum while the blue part is not absorbed by the water molecules and it (the blue part) is scattered by these molecules in the water. Therefore, the water of the sea, lake and swimming pool looks blue.
Why do some of the ocean and lake places look dark, blueish-green or green and muddy instead of blue?
A question arises when we say, the ocean is blue, that is ; Why do some of the ocean and lake places look dark, blueish-green or green and muddy instead of Blue?
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| (Blue water) |
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| (Dark water) |
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| (Green water) |
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| (Muddy water) |
Now, let's know the reasons for this. Hardly any light penetrates to a depth of more than 200 meters (656 feet), but according to the study, sunlight can penetrate into the ocean up to 1,000 meters (3,280 feet) and not exceed. So, after a depth of 1,000 meters, the light cannot reach much, therefore, this place of the ocean looks dark. And some places in the lake and ocean also have some type of matter in their water, which can absorb all kinds of light, so their water looks dark.
Some places of ocean and lake appear blueish-green or green, because of micro and macro-organisms and mineral particles present in the water (also known as "colored dissolved organic matter" or CDOM). And the last one is the muddy color of water. Generally, the muddy color appears in lake water (also in river and estuary water) and this is due to the silt present in it.
Why do we study about the color of the ocean?
The study of the color of the ocean is very useful for us, because the study of the color of the ocean helps scientists learn about phytoplankton and their effect on the earth system and it sometimes helps to know about the depth of the ocean.
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