Why is the sky blue and the sea blue?

Answer 1

Why is the sky blue?
The sky is blue partly because air scatters short-wavelength light in preference to longer wavelengths. Combined, these effects scatter (bend away in all directions) some short, blue light waves while allowing almost all longer, red light waves to pass straight through. When we look toward a part of the sky not near the sun, the blue color we see is blue light waves scattered down toward us from the white sunlight passing through the air overhead. Near sunrise and sunset, most of the light we see comes in nearly tangent to the Earth's surface, so that the light's path through the atmosphere is so long that much of the blue and even yellow light is scattered out, leaving the sun rays and the clouds it illuminates red.

Scattering and absorption are major causes of the attenuation of radiation by the atmosphere. Scattering varies as a function of the ratio of the particle diameter to the wavelength of the radiation. When this ratio is less than about one-tenth, Rayleigh scattering occurs in which the scattering coefficient varies inversely as the fourth power of the wavelength. At larger values of the ratio of particle diameter to wavelength, the scattering varies in a complex fashion described, for spherical particles, by the Mie theory; at a ratio of the order of 10, the laws of geometric optics begin to apply.

Why is the sky blue instead of violet?
Because of the strong wavelength dependence (inverse fourth power) of light scattering according to Raleigh's Law, one would expect that the sky would appear more violet than blue, the former having a shorter wavelength than the latter. There is a simple physiological explanation for this apparent conundrum. Simply put, the human eye cannot detect violet light in presence of light with longer wavelengths. There is a reason for this. It turns out that the human eye's high resolution color-detection system is made of proteins and chromophores (which together make up photoreceptor cells or "Cone" structures in the eye's fovea) that are sensitive to different wavelengths in the visible spectrum (400 nm–700 nm). In fact, there are three major protein-chromophore sensors that have peak sensitivities to yellowish-green (564 nm), bluish-green (534 nm), and blue-violet (420 nm) light. The brain uses the different responses of these chromophores to interpret the spectrum of the light that reaches the retina.

When one experimentally plots the sensitivity curves for the three color sensors (identified here as long (L), middle (M), and short (S) wavelength), three roughly "bell-curve" distributions are seen to overlap one another and cover the visible spectrum. We depend on this overlap for color sensing to detect the entire spectrum of visible light. For example, monochromatic violet light at 400 nm mostly stimulates the S receptors, but also slightly stimulates the L and M receptors, with the L receptor having the stronger response. This combination of stimuli is interpreted by the brain as violet. Monochromatic blue light, on the other hand, stimulates the M receptor more than the L receptor. Skylight is not monochromatic; it contains a mixture of light covering much of the spectrum. The combination of strong violet light with weaker blue and even weaker green and yellow strongly stimulates the S receptor, and stimulates the M receptor more than the L receptor. As a result, this mixture of wavelengths is perceived by the brain as blue rather than violet.

and

Why is the sea blue?
A common misconception concerning the color of water in large bodies, such as the ocean, is that the blue is due to the reflections from the sky on its surface. This is not true, but was believed to be so decades ago. The real reason the ocean is blue is because the water, pure water, is blue. Yes, according to its frequency spectra, water is a very light shade of turquoise blue. But you need a huge amount of it to really see its color. It’s like a teaspoon of oil, it looks transparent on a white spoon, but in the bottle looks yellowish.

If the ocean owed its color to the sky, it would be a lighter shade of blue and it would be white on cloudy days. You can see clouds reflected in the surface on the sea, but they don’t completely change its color. Some constituents of sea water can influence the shade of blue you see in the ocean. This is why it can look greener or bluer in different areas. Swimming pools with white bottom, would have water that look transparent not turquoise blue, as it is observed even in indoor pools, where there’s no sky to be reflected. The scientific explanation involves the theory of radiative transfer (absorption and scattering), and material electromagnetic spectra.

Particular matter
The color of a water sample is caused by both dissolved and particulate material in water, and is measured in Hazen Units (HU). Either of these components can be deeply colored, for instance dissolved organic molecules called tannins can result in dark brown colors, or algae floating in the water ("particles") can impart a green color. But in a lot of cases water is a clear to neutral color due to a lack of pigments in the water. (e.g. the sea)

The color of a water sample can be reported as:

1. Apparent color
2. True color

Apparent color is the color of the whole water sample, and consists of color due to both dissolved and suspended components.

True color is measured by filtering the water sample to remove all suspended material, and measuring the color of the filtered water, which represents color due to dissolved components.

Testing for color can be a quick and easy test which often reflects the amount of organic material in the water (although certain inorganic components like iron or manganese can also impart color).

You could get more information from the 2 links below...

Answer 2

Blue Sea

Answer 3

Ocean:
Sunlight is made up of all the colors of the rainbow: red, orange, yellow, green, blue, and violet. Some of the sunlight is reflected off the surface of the water, reflecting the color of the sky. Some of the sunlight penetrates the water and is scattered by ripples and particles in the water (this tinges the appearance of the ocean with the color of the particles). In deep water, much of the sunlight is scattered by the oxygen in the water, and this scatters more of the blue light.

Water absorbs more of the red light in sunlight; the water also enhances the scattering of blue light. Sir Chandrasekhar Venkata Raman (an Indian physicist) won the Nobel prize in 1930 for his work on light.


Some Oddly-Colored Seas:
The Red Sea often looks red because of red algae that live in this sea.
The Black Sea looks almost black because it has a high concentration of hydrogen sulfide (which appears black).

Sky:
A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light. When we look towards the sun at sunset, we see red and orange colours because the blue light has been scattered out and away from the line of sight.

Answer 4

The sea is not blue. If you scoop up a cup of it you'll see that, in some areas, it's clear and some places are polluted. Regardless, the sea is a reflection of the blue sky.
The sky is blue because when the sun shines, some of the light rays are long, cut through the particles clouds and such and blah blah blah. However other rays aren't so lucky and they bounce off the particles and clouds and such and reflect back into the atmos. That's what we see. Well something like that. ;-D

Answer 5

The blue color of the sky is due to something called Rayleigh scattering. As light passes through the atmosphere, most of the longer wavelengths go straight through. The longer wavelengths of light are red, orange and yellow. So, those colors of light zip right through. However, much of the shorter wavelength light (like blue) is absorbed by molecules in the atmosphere. This absorbed blue light is then radiated in all directions. Therefore, it gets scattered so that wherever you look some of this blue light reaches you. This makes the sky appear blue in daylight.

The sea appears blue because it reflects the blue sky.

http://www.sciencemadesimple.com/sky_blue.html

Answer 6

Sky is blue because our atmosphere refracts the incoming light from the sun and blue is the color that is seen after that refraction of light.

As for the sea being blue, not sure, but I have a feeling it's due to a relatively similar occurrence.

Answer 7

the Sky nor the Sea is Blue , it looks Blue as Blue is a strong Colour , and when the sunlight fall on the earth , the light reflects on the earth atsomospher and the clour blue stands out on it`s own and hence it`s the colur blue that gives it`s colour to the sky and sea .

Answer 8

The sky is blue cos of how far apart the particles are in our atmopshere and the light refracting through them. Similarly it's red on Mars cos the particles are a different distance apart.

The sea is blue cos it's a reflection of the sky.

Answer 9

the sea is not blue it is just the reflection of the sky and the sky is blue because space is dark blue and as it gets close to oxeygen and stuff like that it gets lighter

Answer 10

The refraction of light through water in the air causes the blue color you see. Same for water, but since the water in the sea is denser, it's a darker shade of blue.

Answer 11

the sea isnt blue, it reflects off of the sky,which is blue. because if you get a glass of water it is clear, well if you out something over it, it turns that color.