1. Structure of the atmosphere
Thermosphere
Altitude (km)
Altitude (miles)
Mesosphere
Ozone Maximum
Stratosphere
Troposphere
Temperature
Ahrens 3rd Edition, p. 82

2. Atmospheric pressure decreases w/ height
Above 99.9%
Above 99%
Altitude, km
Altitude, mi
Above 90%
Above 50%
Pressure, mb
50 percent of mass of the atmosphere is within 6 km of the surface
Ahrens 4th Edition, p. 34

3. Composition of the atmosphere
78% nitrogen N2
20.6% oxygen O2
< 1% argon A
0.4% water vapor H2O
0.036% carbon dioxide CO2
traces of other gases: Ne, He, Kr, H, O3