Why the sky is blue and not green?

Question

Why the sky is blue and not green?

Answer 1

Transmitted light (from the sun, light bulbs, fire, etc) is made up of a spectrum of colors. The longest wavelengths of light are on the red end of the spectrum and the shortest wavelengths are on the blue/violet end of the spectrum.

There is a puzzle of why it is not violet.

http://math.ucr.edu/home/baez/physics/Ge...

Answer 2

Cause its not purple :)

Answer 3

Because light from the sun is scattering by atoms and molecules in the atmosphere.

Light scattering by particles depends on the relative "sizes" of the photons and the particles.

In the case of visible light, molecules are much smaller than the wavelength of light, so blue light gets scattered much more than red light.

So as light from the sun enters the atmosphere, more blue photons get reflected (not absorbed) by molecules than red photons - but then the blue photons get reflected again and again until they reach us. So the blue light comes from all over, the red light comes almost straight from the sun.

This is also why the sun looks redder at sunrise and sunset - the light's path through the atmosphere is longer when the sun is on the horizon than when it is high in the sky.

Interaction of light with the atmosphere does all sorts of weird and wonderful things that physics can explain:

http://hyperphysics.phy-astr.gsu.edu/Hba...

Answer 4

Because Oxygen reflects blue light, and not the wavelengths that make up green light. It's the same reason water is blue. The upper atmosphere is mostly ozone, which is oxygen.

Answer 5

OMG i'm going to sound like such a dork for answering this, okay so visable light, UV, and IR come from the sun. basicly the 7 colors are scattered, the blue, green and violet, have the shortest wave lenghths and our eyes only pick up the blue for some reason.

Answer 6

can you give me an example why it should be green?

i don't really know the answer but...

maybe the color of the solar system is dark blue and because of the light coming from the sun the dark blue became blue..

Answer 7

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.

Tyndall Effect

The first steps towards correctly explaining the colour of the sky were taken by John Tyndall in 1859.  He discovered that when light passes through a clear fluid holding small particles in suspension, the shorter blue wavelengths are scattered more strongly than the red.  This can be demonstrated by shining a beam of white light through a tank of water with a little milk or soap mixed in.  From the side, the beam can be seen by the blue light it scatters; but the light seen directly from the end is reddened after it has passed through the tank.  The scattered light can also be shown to be polarised using a filter of polarised light, just as the sky appears a deeper blue through polaroid sun glasses.

This is most correctly called the Tyndall effect, but it is more commonly known to physicists as Rayleigh scattering--after Lord Rayleigh, who studied it in more detail a few years later.  He showed that the amount of light scattered is inversely proportional to the fourth power of wavelength for sufficiently small particles.  It follows that blue light is scattered more than red light by a factor of (700/400)4 ~= 10.

Answer 8

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 colors 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 colors of the rainbow.  This was demonstrated by Isaac Newton, who used a prism to separate the different colors and so form a spectrum.  The colors 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 color receptors in the retina of the human eye respond most strongly to red, green and blue wavelengths, giving us our color vision.

Answer 9

Its blue because as light passes through the Earth's atmosphere the blue part of the spectrum is bent the most so we see blue. Same reason the Sun looks orange or reddish during a sun set or sun rise because red light bends the least so it bends around the edge of the Earth.That is also why during a lunar eclipse the moon appears red.

Answer 10

because thats just the way it is lol...just live life happy :)