On a nice day why is the sky blue and why is it black at night?

Answer 1

During the day, light from the Sun is scattered by our atmosphere. The process is called Raleigh scattering. In this process, the shortest wavelengths of light are scattered the most, meaning that violet, blue, and green light get scattered more strongly, while yellow, orange, and red light do not.

At night, there is no sunlight being scattered and the sky is dark.

Note that the color of the sky has nothing to do with ozone, or oxygen, or water vapor. Even if the sky was made of helium or carbon dioxide, it would still appear blue in the daytime. This is because Raleigh scattering is based on the size of the molecules in the air, not what it is made of.

Answer 2

I was going to answer but aichip_mark2 got there first.
Just to head of some of the inevitable wrong answers the sky is not blue because of the sea, the sea is blue because of the sky.

Actually I just reread aichip_mark2's reply. Don't be so sure that atmospheric composition has nothing to do with the colour. I have not done the sums but I would be surprised if rayleigh scattering from hydrogen produces the same spectra as from CO2.

Answer 3

aichip_mark2 is almost on the mark except for the constitution part. The constitution of the sky will affect slightly, not much but it will. The effect will be the hues of the blue colour you see. The only time the constituents can have a drastic effect is if there is a large no. of particulate matter in the atmoshphere. If its only gases you will see bule in all skies of all planets as long as you have a thick enough atmosphere to scatter the rays.

Answer 4

someone said that water is not blue.
well, it is. its pretty translucent though so when viewed through a cup you dont see any colour.

its correct to say its reflected light to a degree but its also the brightness of the sun which hides the blackness of space.

think of the sun as a spotlight. when its on us we see, when the earth turns on its axis we go out of the spotlight and into darkness.

the days are longer in the summer in the uk because as the earth goes around the sun its not on a circular path. so in the summer its slightly closer to the sun than in winter.

the light you see from the moon is also reflected sunlight. it gives off no light of its own.

same is for all the other planets in the solar ystem too.

this is also the reason why it is difficult for astronomers to spot planets going around other stars.
they have to watch the stars and see if they blink. this might indicate that something is passing between us and the distand star.

most stars appear to blink to us though through our atmosphere.

if you really want to see what the night sky looks like you have to get away from cities and into the countryside. the light from towns and cities filter out starlight in a similar way to the sun.

get out in the country on a moonless night and its amazing.

you cant help but wonder is there anyone out there when you see all those stars.

Answer 5

For me, the above answers are wrong.


Have you ever went to a sea and saw the water there? If yes, what colour was it? Blue! If you transfered it to a cup, see its colour now!

Ozone Layer is blue. What you see is ozone layer, as far as I know.
At night the sunlight is on the other side of the world the most! So if you put a blue paper as ozone under light, what color would you see?

Try it in a dark room, isn't it black?



This is my answer, even if it is question(s)!!!

Answer 6

The sun, shining through our atmosphere, reflecting off the water droplets makes the sky appear blue. At night, the sun's shining on the other side of the Earth, so the sky loses its blue hue and all you see is space....which is black.

Answer 7

Its blue because the sun has just got up.Its black at night because its gone to bed and turned the light out.

Answer 8

The reason it gets dark at night is because the last person going to bed turns the lights out!

Answer 9

sometimes its a dark blue sky at night

but what happens when you turn off a light in a room?
whoa blackness, silly me, there's no source of light.

Blueness at daytime is a result of raleigh scattering of sunlight off atmospheric molecules.

And the redness at sunset is scattering off atmospheric dust in the lower atmosphere.

Answer 10

Ha Ha Ha Ha Ha Ha, get your mom to read you a bedtime story