Compare and Contrast how it used to be and how it is now?

Question

Can somebody here provide me with links about the sky (earth's blue sky) I want 2 pics..just two

1) A Clean Blue Sky

&

2) A polluted sky

I want to see both, to compare them and see all the stuff about global warming and greenhouse gasses and whatsoever.

So lets make this clear:

Best pictures = Best Answer

Best Answer = Best feedback

You get it ;)

Thanks! :D

Answer 1

Deveral of clear skies.

http://images.search.yahoo.com/search/im...

Several of pollution.

http://images.search.yahoo.com/search/im...