Incidentally and aside from its aëronautic interest, the composition of the atmosphere may be presented in fuller detail, showing the wide variations from level to level, and the manifold complexity of the fluid we daily breathe, not to mention the myriads of motes and germs inhabiting every inch of it. The gaseous components and their distribution are well exhibited in the following table,[57] which represents an average condition: TABLE I _Percentage Distribution of Gases in the Atmosphere_ Key: HT = Height in Kilometers. A = Argon. N = Nitrogen. WV = Water Vapor. O = Oxygen. CD = Carbon Dioxide. HY = Hydrogen. HE = Helium. TP = Total Pressure in Millimeters. ----+--------------------------------------------------+-------- | GASES. | HT +------+-------+------+------+------+-------+------+ TP | A | N | WV | O | CD | HY | HE | ----+------+-------+------+------+------+-------+------+-------- 150 | | | | | | 99.73 | 0.27 | 0.0043 140 | | | | | | 99.70 | 0.30 | 0.0048 130 | | 0.02 | | | | 99.64 | 0.34 | 0.0054 120 | | 0.10 | | | | 99.52 | 0.38 | 0.0060 110 | | 0.40 | | 0.02 | | 99.16 | 0.42 | 0.0067 100 | | 1.63 | | 0.07 | | 97.84 | 0.46 | 0.0076 90 | | 6.57 | | 0.32 | | 92.62 | 0.49 | 0.0090 80 | | 22.70 | | 1.38 | | 75.47 | 0.45 | 0.0123 70 | 0.02 | 53.73 | | 4.0 | | 41.95 | 0.27 | 0.0248 60 | 0.04 | 78.16 | | 7.32 | | 14.33 | 0.15 | 0.0810 50 | 0.08 | 86.16 | |10.01 | | 3.72 | 0.03 | 0.466 40 | 0.16 | 86.51 | |12.45 | | 0.88 | | 1.65 30 | 0.22 | 84.48 | |15.10 | | 0.20 | | 8.04 20 | 0.55 | 81.34 | |18.05 | 0.01 | 0.05 | | 39.6 15 | 0.74 | 79.56 | |19.66 | 0.02 | 0.02 | | 88.2 11 | 0.94 | 78.02 | 0.01 |20.99 | 0.03 | 0.01 | |168 5 | 0.94 | 77.89 | 0.18 |20.95 | 0.03 | 0.01 | |405 0 | 0.93 | 77.08 | 1.20 |20.75 | 0.03 | 0.01 | |760 ----+------+-------+------+------+------+-------+------+--------