Or is it an optical illusion?

In my lifetime I have seen many balloons floating up into the sky... But where do they go?

@ what speed would I need to fly heading west to be able to keep looking @ a sunset.....(what speed is the night time shadow across the earth)

What makes the sky change colour at different angles and directions?

a: Where does the sky get its colours/gradient come from?

b: Why is the sky blue above and red towards the horizon? Why not the other way around?

Thanks!

Likewise why is the air hazy and clouds melt into one another as well as appear more diffuse?

On the first night of heavy snow - tues 5th Jan - it was cloudy but the sky was  a very light sepia tone all night - enough to see clearly by. It was much more light than on the subsequent nights which have been partially cloudy with a visible moon. On these nights there was the same amount of snow cover, but less cloud. 

On the sepia night it was lighter than if there had been a full moon.

Do we all perceive color the same way ? for example do we all see the same color green or is the word green or red or blue just names to tag how we perceive those color. If I switched eyes with someone he might see the grass the same way as I perceive the sky but still call it green even though for me it would be blue.

The same goes for colorblind people (those unfortunate to mix up colors) if they were brought up seeing the grass as we would see it red. He would say green to everything red if we were able to see through his eyes. It would rely on education then.

Do I make sense ?