Sunday, January 8, 2017

atmospheric science - Pressure at a given altitude?


I am trying to find out the pressure at a given altitude but have been disappointed to find the following equation does not work at all: (h = height in meters)


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Where



  • sea level standard atmospheric pressure p0 = 101325 Pa

  • sea level standard temperature T0 = 288.15 K

  • Earth-surface gravitational acceleration g = 9.80665 m/s2.


  • temperature lapse rate L = 0.0065 K/m

  • universal gas constant R = 8.31447 J/(mol·K)

  • molar mass of dry air M = 0.0289644 kg/mol


( from Wikipedia )


Upon completion of the equation, which I think spits out Pascal values, they don't match what a pressure would realistically look like at that altitude (comparing the output value to one from Wolfram). Any idea what the issue with this equation is?


EDIT: inaccuracy alone isn't the problem, it's not giving the right values for anything. I saw a value of 101800 or so for an altitude of 800ft, which is completely wrong, and then the output starts turning into negatives around 100,000ft. I do need something to work at that height, perhaps this isn't the equation for me?




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