Why is the sky blue?

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.

When transmitted light such as sunlight enters our atmosphere it collides with the oxygen and nitrogen atoms. The color with the shorter wavelength is scattered more by this collision. Because violet and blue are the shortest wavelengths the sky appears to be violet / blue. But because our eyes are more sensitive to blue light than they are violet light, we perceive the sky as blue.

Our eyes contain thousand of rods and cones, which are the receptors for light. Whenever one of the 3 Stooges pokes you in the eye you see a giant blue spot. This is because the blue receptors have been activated. Blue is one of the primary colors and thus more easily activated and seen by our eyes.

Why is the sky blue: Summary
So, why is the sky blue? It is because blue light from the sun strikes the air molecules and scatters and our eyes perceive it as blue.

Why is the sky blue: Short Summary:
Why is the sky blue, you ask? Blue in sunlight collides with air molecules and our eyes see it as blue.

Why is the sky blue: Condensed
Sunlight collides with air, scatters blue wavelengths.

Why is the sky blue: Ultra-Condensed.
You are seeing things. Stop asking ;)

Answer 2

Atoms, molecules and all tiny particles re-emit light waves that shine on them like little optical tuning forks. The tinier the particle, the higher the frequency of light it will scatter. Violet has the highest frequency of the visible light frequencies and is scattered the most followed by blue, green, yellow, orange and red. Our eyes are more sensitive to blue light so the sky looks blue. The blue of the sky varies under different conditions. Where the atmosphere is more polluted and has a lot of particles other than nitrogen and oxygen, the lower frequencies of light are scattered more so the sky is a lighter blue or can even appear whitish. The higher in the atmosphere you travel, the fewer molecules are there to scatter light so the sky appears darker. On the moon, the sky is black.
The color of water is cyan (blue-green). Water will look a deep blue sometimes because it is reflecting the color of the sky, not the other way around.

Answer 3

So is air.

Air is blue, but you need to be in a big pool of it (The Earth's atmosphere) to notice the colour.

Same story with water.

Answer 4

It's the reflection of the ocean off of the sun, hence cloudy gray sky days.

Or hence the black at night.

Answer 5

think of a prism, when light goes through it, you see all the colors of the rainbow we see blue usually the entire day but at night it turns red due to the angle the light is passing through our atmosphere

Answer 6

ocean water reflects the light back onto the particles in the aptmosphere

Answer 7

because of the way the sunlight reflects off the gases in the atmosphere

Answer 8

if it were green we would know where to stop mowing.

Answer 9

because that's the way god made it

Answer 10

yes it is