What Causes the Color of the Sky and the Behavior of Light?

[humanbeing]

abou light...

hi,

I have some question about light.
In the earth, we can see the sky as blue during the day.
In the outerspace, we can see the universe as black, although the sun is nearby.
Why?

In a dark room, we can see a light pass through.
In a street, we can't see the light passing through from the lamp.
Is the distance between the lamp and ground effect? Or the other light cover the light of the lamp?

In the morning, the light appear before the sun rise.
But the light haven't reflect by anything.
Why we can see the light?
Is the light reflect by the air? Or the air is one of the media of light to spread?

 

[G01]

hi,

I have some question about light.
In the earth, we can see the sky as blue during the day.
In the outerspace, we can see the universe as black, although the sun is nearby.
Why?

The sky is blue due to Raleigh scattering. The blue light from the sun gets scattered and dispersed more than the red light. Thus, we see blue light coming at us from all directions and thus the sky appears blue.

In the evening, the sun is at an angle such that it passes through more atmosphere and the blue light is scattered so much that little of it makes it to our eyes. Thus, the sun appears red/orangish at sunset.

In a dark room, we can see a light pass through.
In a street, we can't see the light passing through from the lamp.
Is the distance between the lamp and ground effect? Or the other light cover the light of the lamp?

Perhaps you can elaborate on your question? I'm not sure what your asking.

In the morning, the light appear before the sun rise.
But the light haven't reflect by anything.
Why we can see the light?
Is the light reflect by the air? Or the air is one of the media of light to spread?

This effect is also caused by the scattering of sunlight by the atmosphere.

 

[humanbeing]

sorry,

for question 2:
In a dark room, we open the flashlight, and we can see a light passing through.
But, how the light reflect to our eyes?
In the street, we can't see that.
Why?

 

[JaredJames]

for question 2:
In a dark room, we open the flashlight, and we can see a light passing through.
But, how the light reflect to our eyes?
In the street, we can't see that.
Why?

You can only 'see' the path of the light if there is something to reflect it back - in other words, dust.

Generally, a house will have more dust floating around than external sources, so you're more likely to see the beam whilst inside.

However, if you are in a clean room with little dust in the air, you will not see the beam.

A good example is to think about a foggy night. On those nights, you can see the beam of light.

 

[humanbeing]

thanks

 

[humanbeing]

And...

For question one,
We can see the sky as blue during the day, although we don't see directly to the sun.
But, we can see the universe as black in the outerspace, when we don't see directly to the sun.
Why?

 

[dacruick]

And...

For question one,
We can see the sky as blue during the day, although we don't see directly to the sun.
But, we can see the universe as black in the outerspace, when we don't see directly to the sun.
Why?

The atmosphere is scatters the light, but in space there is no atmosphere. This means that there is nothing to change the direction of the light, or disperse the light. You see black simply because there is nothing reflecting or refracting light from that direction.

 

[humanbeing]

When I back to the sun, how does the light scattering to my eyes?

 

[JaredJames]

When I back to the sun, how does the light scattering to my eyes?

If the light doesn't reflect off something, you don't see it.

 

[mishrashubham]

sorry,

for question 2:
In a dark room, we open the flashlight, and we can see a light passing through.

Its the Tyndall Effect
http://en.wikipedia.org/wiki/Tyndall_effect

 

[DaveC426913]

You can only 'see' the path of the light if there is something to reflect it back - in other words, dust.

Generally, a house will have more dust floating around than external sources, so you're more likely to see the beam whilst inside.

However, if you are in a clean room with little dust in the air, you will not see the beam.

A good example is to think about a foggy night. On those nights, you can see the beam of light.

Note one other important difference between a flashlight and a streetlight. A flashlight is a directed beam - it has a well-defined edge between lit an unlit areas. A streetlight is, for practical purposes, an omnidirectional light source, meaning its light is cast in all directions. Essentially there is no edge of beam to see.

 

[DaveC426913]

When I back to the sun, how does the light scattering to my eyes?

The atmosphere is pretty effective at scattering. The atmo looks pretty much as bright no matter what direction you are looking, meaning pretty much the same amount of light is being scattered in any given direction.

However, now that you know to look for subtleties, you can start to see where this is not quite so. Look for differences between near the horizon and near the zenith, as well as toward the sun and away from it.