When flying over most of the country it is easy to spot many types of infrastructure, both man made and natural. Streams become rivers become oceans and driveways become routes become highways. These infrastructures, for the most part lay ON grade. Many view the electrical system as hanging above us, but it is also still grounded on the earth via production and transportation. There has been recent study and interest taken upon underground infrastructures, pipes and tunnels that run underneath New York or Chicago carrying the heavy burden of water and sewage for their respective populations. These infrastructures listed above, are either man made or natural, yes there are some intersections, i.e. canals. But I can not think of a more integrated infrastructure between existing natural conditions and man-made needs than air travel. Air travel is directly dependent on natural jet streams and wind patterns which can not be paved or contained in a pipe. As many have witnessed, when a plane does not directly coincide with these patterns, turbulence occurs. If you look at the infrastructures of the earth and its atmosphere in section, do we integrate farther as we reach high elevations? or is this a unique condition to air travel?