Calibration was accomplished by observing the drop in transducer output as the capsule ascended. In the standard atmosphere, the air pressure drops by a factor of two every 18,000 foot increase in altitude. The change in transducer voltages between altitudes of 18,000, 36,000, 54,000, and 72,000 where averaged. This average is then subtracted from the voltage at 18,000 feet to determine the base voltage of the transducer, which becomes the Y intercept in a transducer voltage to pressure function.
Becasue of weight, an environmental sounder was not flown on this mission. However the data from the insect cabins can be used to characterize the temperature and pressure of the atmosphere as a function of altitude.
The lowest air temperature encountered in a near space balloon flight occurs
at the troposphere-stratosphere boundary, or at the tropopause. The altitude
of the tropopause lowers in the winter and rises in the summer. It
also changes as a function of lattitude. In the above graph you can see that the
tropopause occurs at an altitude of 45,000 feet.
The above graph illustrates that the air pressure drops as a logrithic curve.
How can we be certain that we're seeing a logrithmic curve here? In the next
graph I plotted the same data (actually the spreadsheet did the plotting)
but on a log-linear scale. The graph now shows a near-straight line.
