why is the sky blue?

the color of the universe !

The sky is blue because blue light comes in on a short wavelength and wallops into oxygen atoms of roughly the same size. When we look up and see a blue sky, we are seeing that interaction.

At sunset, we see more red because the sunlight is passing throgh many more miles of low atmosphere at that low angle near the horizon. The blue light interacts with the oxygen and is scattered as before - but cannot reach the eye throgh the extra miles at this time. Instead we see the other end of the spectrum, the red light.

Why is the sky blue?

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.

The white light from the sun is a mixture of all colours of the rainbow. This was demonstrated by Isaac Newton, who used a prism to separate the different colours and so form a spectrum. The colours of light are distinguished by their different wavelengths. The visible part of the spectrum ranges from red light with a wavelength of about 720 nm, to violet with a wavelength of about 380 nm, with orange, yellow, green, blue and indigo between. The three different types of colour receptors in the retina of the human eye respond most strongly to red, green and blue wavelengths, giving us our colour vision

When we look up at the sky, the red cones respond to the small amount of scattered red light, but also less strongly to orange and yellow wavelengths. The green cones respond to yellow and the more strongly-scattered green and green-blue wavelengths. The blue cones are stimulated by colours near blue wavelengths which are very strongly scattered. If there were no indigo and violet in the spectrum, the sky would appear blue with a slight green tinge. However, the most strongly scattered indigo and violet wavelengths stimulate the red cones slightly as well as the blue, which is why these colours appear blue with an added red tinge. The net effect is that the red and green cones are stimulated about equally by the light from the sky, while the blue is stimulated more strongly. This combination accounts for the pale sky blue colour. It may not be a coincidence that our vision is adjusted to see the sky as a pure

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.

Why is the sky blue?

Blue sky: short explanation

Blue light gets scattered (spread) around much more than all the other colors from the sun, causing the sky to appear blue.

Blue sky: a more detailed explanation

Light is made up of electromagnetic waves.

The distance between 2 crests in this wave is called the wavelength.

White light contains all the colors of the rainbow.

The amount of light scattered for any given colour depends on the wavelength of that colour.

All the colors in white light have different wavelengths.

Red light has the longest wavelength.

The wavelength of blue light is about half that of red light.

This difference in wavelength causes blue light to be scattered nearly ten times more than red light. Lord Rayleigh studied this phenomena in detail. It is caused the Tyndall effect or Rayleigh scattering.

Lord Rayleigh also calculated that even without smoke and dust in the atmosphere, the oxygen and nitrogen molecules would still cause the sky to appear blue because of scattering.

When blue light waves try to go straight through an oxygen and nitrogen molecules, its light is scattered in all directions because of this collision.

This scattered blue light is what makes the sky blue.

All other colors (with longer wavelengths than blue light) are scattered too.

Blue light's short wavelength causes it to be scattered the most.

(The shorther the wavelength of the color, the more that color gets scattered by the atmosphere)

Actually, violet has the shortest wavelength of all colors. Violet is scattered even more than blue light. However, our eyes are much more sensitive to see blue than violet, therefore we see the sky as blue.

Very little visible light is absorbed by the atmosphere.

Blue sky: summary

Blue light's short wavelength causes it to get scattered around 10 times more by oxygen and nitrogen molecules than the longer wavelengths (like red) of the other colors visible to us.

The blue in the sky we see is scattered blue light.

Take these short online quizzes to test your understanding of this blue sky explanation

Why the Sky is Blue, a Poem by John Ciardi

I don't suppose you happen to know

Why the sky is blue? It's because the snow

Takes out the white. That leaves it clean

For the trees and grass to take out the green.

Then pears and bananas start to mellow,

And bit by bit they take out the yellow.

The sunsets, of course, take out the red

And pour it into the ocean bed

Or behind the mountains in the west.

You take all that out and the rest

Couldn't be anything else but blue.

Look for yourself. You can see it's true.

The sky is blue because of a process called Rayleigh scattering. Light arriving from the Sun hits the atmosphere, hitting all the molecules in the air and is scattered in all directions. The amount of scattering depends on the frequency of the light (the colour). Blue light which has a higher frequency is scattered more than red light and in the middle of the day this appears as blue as the background colour of the sky.

At sunset the light has to pass through more air due to the angle it arrives and we see more orange and reds getting through.

The white light from the sun is composed of a spectrum of light, including from reds to blues. The sky is blue because blue light is scattered far more easily than red light. Less blue light go straight down to the ground, than red light.

The tecnical explanation can be found in the link below. Notice that the scattering of light varies inversely with the FOURTH power of frequency. So that, for example, if blue light is 2 times the frequency of red light, then 16 times as much blue light would be scattered than red light.

The Earth's atmosphere acts as a prism, so when light hits it it separates. The wavelength absorbed by the atmosphere is about 475 nanometres which, when it enters our eye, makes the sky appear blue

Because of all the chemicals that fly around in the atmophere make the sky blue. If its grey then that means there is alot of rain in the clouds (H2O). If its red than it means that the sun is giving off a reflection of another chemical.

If you haven't learned this in high school science yet, you will. It's a matter of wavelengths based on gases in the atmosphere (sky) affecting how the sun's light rays are filtered. It's the same science that determines how we see any colors at all.

The sky isn't actually blue. It is black but the sunlight makes it look as though it is blue.