why sky is seen to be blue in colour ?

Question

Normally at daytime we can see the sky looking blue in colour . what is the reason for sky colour change ?

Answer 1

The earth's atmosphere scatters light. That is why the sky is black at night (no light to scatter). If you notice that toward the end of the day at sunset the sky turns orange and red.

That is because of your viewing angle relative to the light passing through the earth's atmosphere. Due to the angle of the light from the sun relative to your eye at sunset, the light has to pass through more of the earth's atmosphere. Orange and Red light have larger wavelengths and are able to penetrate the atmosphere, while blue light is not.

That is why the sky is blue during the day, the higher energy (shorter wavelengths) of the blue light cannot escape into space through the atmosphere, it scatters making the sky appear blue.

Answer 2

This gets asked loads and answered, usually, badly. Rayleigh scattering often gets mentioned. What does that tell you ? You might learn two new words "Rayleigh" and "scattering" but what else ? Does it explain to you why different coloured light is scattered differently ? Thats what the "blue sky" question is really asking.

If you want to know what really happens .....

Forget the atmosphere for a moment, just imagine a single electron and a red photon (which has little energy) and a blue photon (which has a lot).
The blue photon has nearly enough energy to lift the electron to a higher energy state, but it doesn't have quite enough so it borrows the extra energy from nothing at all (really, energy is borrowed from nothing !!!). But, Mother natures rule for borrowing energy is "the more you borrow the sooner you have to give it back". So now we have an electron in a high energy state due to the energy from the blue photon and the borrowed energy. Because only a little bit of energy was borrowed (remember the rule) it can stay in this state for quite a long time before mother nature asks for her energy back. When that happens the blue photon is "kicked back out" of the electron.
The key point is that the electron is part of an atom (say a Nitrogen atom in the atmosphere) and that atom is spinning so it can turn quite a long way round in the time between when the blue photon was absorbed and emitted. The practical upshot of which is that the blue photon approaches the atom from one direction but departs in a very different direction or is "scattered". So all blue light is scattered from all Nitrogen atoms in the atmosphere all around so the sky appears blue. Voila !

A red photon (less energy) to boost an electron to a higher level has to borrow a lot of energy and so has to pay it back sooner. That means the atom won't have turned very far before the red photon is fired out again. So its fired out in pretty much the same direction as it arrived.

Its a bit like jumping on a a merry-go-round. If you stay on for a few seconds, when jump off you'll be travelling in a completely different direction. If you jump on then straight off you'll be travelling in pretty much the same direction as when you jumped on.

Answer 3

The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.

However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.

As you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white.

Answer 4

The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.

However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.

As you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white.

Answer 5

It is due to angle relative to the light passing through the earth's atmosphere. The angle of the light from the sun relative to your eye at sunset, the light pass through more of the earth's atmosphere.

Lights like orange and red l have larger wavelengths that penetrate the atmosphere, while blue light is not.

Therefore, sky is blue during the day, the higher energy with shorter wavelengths, of the blue light cannot escape into space and scatered in the atmosphere. Thus sky appear blue

Answer 6

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

"The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.

However, much of the shorter wavelength light [(blue light)] is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue. "

Answer 7

Once and for all, the fact that the sky is blue has absolutely nothing to do with refraction or the color of water.

As some of the people have posted, the correct explanation is Rayliegh scattering of light in the atmosphere, period.

Answer 8

the sky is looking blue becuz there r many colours in the sunlight.when they pass through the atmosphere of the sky,blue colour is most prominent.like this r the colours of water sources.

Answer 9

Hey Joe,you know wrong about the sky's colour.Sky is not only seen in blue.It colours also red,pink etc in different times.It is dependent on that in which way our Earth reflects the Sunlight.Therefor in different time of day the sky seens in different colour.Because it is dependent too on that from which angle does the Sun sending lights to Earth and how the Earth reflects.

Answer 10

The skies color is due to the refraction of light in the upper atmosphere.
Even during times after rains we see that the sky is dark grey whereas there is a lighter shade to this color at other times.
This goes to show that water molecules are responsible for the maximum amount of scattering of light in the atmosphere.