Sky
From Simple English Wikipedia, the free encyclopedia
The sky Is what we call the appearance of a hemisphere over our heads. On a clear day it appears blue. The depth of the "blueness" increases as we move from the horizon to the point above our head. The reason the sky is blue is due to Raleigh scattering - a phenomenon which defines the amount of scattering of light rays. Since all colors of the rainbow create a white light we ought to see white skies, but in fact blue light scatters much more than red and therefore that is why the sky appears blue ( on a cloudless day) In all cases I am assuming a clear sky in daylight.
The reason we see beautiful red sunsets is the same in reverse. The rays of the setting sun in the artificial hemishphere - have to travel further through the atmosphere. Since the blue light is scattered more it does not reach our eyes and the red light which is scatted much less does reach our eyes.
In fact the famous question all children ask their parents = why is the sky blue Daddy? is actually meaningless! It all depends what you mean. If you could take of vertically for 8 miles ( 40000 ft) you would notice the sky was a somewhat deeper blue even in the day. If you flew Concorde at say 60-65000 ft the sky would be noticeably darker and if you were an astronaut it would go from deep indigo to jet back as you traveled from 100 mls to say 300 miles up. So what we see when we look up is not really "there"
