Atmospheric Pressure  where
-  = pressure at altitude
 
-  = standard pressure at sea level (101325 Pa)
 
-  = Temperature lapse rate (0.0065 K/m)
 
-  = The altitude in question
 
-  = standard temperature at sea level (288.15 K)
 
- = Earth surface gravitational acceleration (9.80665)
 
-  = Molar mass of dry air (0.0289644 kg/mol)
 
-  = Universal gas constant (8.31447 J/(mol•K))
 
Terminal Velocity  where
-  = velocity at the specified altitude
 
-  = Mass of falling object
 
-  = gravitational acceleration
 
-  = projected area of the object
 
-  = Coefficient of drag of the object
 
-  = Density of the fluid through which the object is falling
 
Density of Air  where
-  = Absolute pressure
 
-  = Specific gas constant for dry air (287.058 J/(kg·K))
 
-  = Absolute temperature
 
Gravity at Altitude  where
-  = Gravity at elevation
 
-  = Gravity at surface
 
-  = Mean radius of the Earth
 
-  = Elevation in question
 
Will need to combine these four functions over time and altitude (third order diff-eq?) to get the result.
Sources: