The world is a big place. The marriage of landscape and sky always yields an awesome spectacle. These landscapes represent four continents (North and South America, Africa and Australia). On the macro level one sees how small man is. However, on closer examination you can witness our impact, even on this seemingly impervious environment.
As big as they are, each of these scenes represents a fragile ecosystem. We (i.e. mankind) have developed the capability to put our indelible mark on the environment. They are scenes that may not exist in 100 years as mankind continues to exploit the planet. Enjoy them now. They may not be here for our great-grandchildren.