|A photo Amazon.com founder Jeff Bezo’s Apr 2015 unmanned test launch of his Blue Origin, a Karman line space tourism aiming spacecraft, which flew to a height of 58 miles, four miles below the 62 mile height Karman line, where the pull of the force of earth’s gravity ends, outerspace starts, and weightlessness begins. (Ѻ)|
In 1663, Otto Guericke, in his Magdeburg Experiments on the Vacuum of Space, stated the following: 
“The air surrounding the earth presses upon itself because it is corporeal and has a certain weight. Indeed, the upper air presses down increasingly heavily on the lower. Thus, it follows that the lower air here, which surrounds us, is much denser than the upper air.”
In another place:
“Air not only becomes more and more rarefied and lighter the higher and higher one goes, but even, if one could go to a distance of 1,000 or say even 2,000 German miles, absolutely nothing more would be left of it and pure space, void of all matter would be found.”— Otto Guericke (1665), “Reply Letter to Sanislaus Lubienietzki”, Jul 22; in New Experiments on the Vacuum of Space (pg. 293)
The use of the Karman line frequently arises in attempts to quantify the earth as a system in a thermodynamic sense. The standard thermodynamics concepts of atmospheric pressure and work become blurry at the Karman line boundary, which thus requires more detailed thought in attempts of formulation. 
1. Theodore von Karman – Wikipedia.
2. (a) Thims, Libb. (2007). Human Chemistry (Volume One) (Karman line, pgs. 64, 312-14). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two) (Karman line, pg. 407).. Morrisville, NC: LuLu.
3. Guericke, Otto. (1663). The Vacuum of Space (De Spatio Vacuo). Unpublished; New Magdeburg Experiments on the Vacuum of Space (Ottonis De Guericke Experimenta Nova (ut vocantur) Magdeburgica de Vacuo Spatio) (preface, pdf) (pg. 112). Janssonius a Waesberge, 1672.
● Karman line – Wikipedia.