Is the sea really blue?

Question

lol had an argument with my flatmate about this.

Answer 1

No cause of the refection of the sky

Answer 2

The reason why the sea seems blue is similar to the reason why the sky is blue -  because the molecules in the atmosphere scatter the blue part of the spectrum, and the red and yellow parts of the spectrum tend to pass straight through.  To us looking from the ground, the blue light seems to be coming from everywhere (this is called 'Rayleigh cattereing'); hence the sky seems blue.

The reason why the sea seems blue is similar,  but a little more complicated.  The sea does reflect the blue colour of the sky (or can appear grey in overcast weather), but this only applies to the surface of the sea.  As with the sky, the water molecules scatter the blue light in much the same way as the air molecules in the sky.  This accounts for the 'natural faint blue colour'.

In addition,  the water also absorbs more of the red and yellow wavelengths (which warm the sea), leaving the blue part of the spectrum, as well as part of the green.  This is why deep water can appear bluish-green. (The absorption of the red wavelengths can be noticed by looking at a red object under deep water.  It will appear black; because only blue light is reflected back to us.)

Eventually, at sufficient depth, even the blue light will have been absorbed or scattered away, and deep water will be black and lightless.

This scattering effect is even stronger if there are colloidal materials (very finely divided particles) in the water, such as finely divided clay particles.  These can increase the scattering effect, turning the water an intense blue (which can sometimes be seen in flooded abandoned quarries).  The scattering effect is also greater with ice; which results in the intense blue colour we see if we look down a crevasse in a glacier, or down a hole in the snow made by a ski stock..

For complete, scientific explanations of the scattering effect, look up 'blue sky' in Wikipedia.

Answer 3

The sea is usually colored by its colored ingredients. This means it can be of all colors.

Because some very common blue algae, the sea is quite often colored blue. There some enhancements to this coloration caused be the Rayleigh Scattering, e. g. form the blue sky above.

Most sea not belonging to the ocean are of different color, most often caused by soluted sediments. So the range of color is wide. -> Mie scattering.

Answer 4

Water is naturally blue in color, yes.  It isn't a very intense blue, but if you have enough water the other colors absorb out - the bond energies in water are primarily in the red end of the spectrum.

Answer 5

no it's the reflection of the sky

Answer 6

no cuz its the reflection of the sunlight on the sky which turns a shade blue while entering atm and a lot of a darker and lighter colours r provided by the impurities present in the sea

and it gets blacker(cuz no sunlight can reach) not bluer as we go deeper

Answer 7

If you cup some in your water, its not blue.

I think its the sky or the rocks underneath,

but if it was the sky, why is the sky blue?

Answer 8

no...i think it's because of the reflection of the sky

Answer 9

It is under 2 conditions. One - the water is very clear. If it has algae or seaweed or plankton or other particles then these things will color the water and most likely make the water appear green or muddy. Two - the sky is blue and clear enough to allow UV radiation to reach the surface. The blue light from the sky will be reflected and the UV radiation will be scattered by the water molecules making the sea a very deep blue. Basically you want the sea to be clean and not dirty or contaminated.

Answer 10

yes it is.its not because of reflection of sky it is because of the salt materials present in it and the depth.the deeper it is the bluer it is.