Quick Math Question... (Pressure conversion)

EDIT: Forget about this… i found the solution here:

(This post can be deleted)

I am trying to convert absolute pressure values to atmospheric pressure.

I found this on the net, but can’t get it to accurately compute… I might not be understanding how to implement the equation in the program…

here’s the equation:

My question is : What to do with the 5.25?? Should it be multiplied?

this is how I am computing it:

P = (P0× (1−(h / 44330.77)))

Then convert from Pascals to inH:
AP = (P÷100)×0.02953

With inputs of:
h = 448
p0 = 100900

I should get: 29.78 Atmospheric Pressure

I am getting: 29.47 Which is close. But not close enough.

I am inputing values from my local airport reports… So I know the WUnderground conversions are correct… So it’s an issue on my part. If I multiple the (5.25) outside the brackets I get values WAY off… So… Any help would be welcomed!

The 5.255876 is an exponent, not a multiplier. You need to take the expression you calculated to the power of 5.255876. (Not difficult to do with Excel or a scientific calculator).

You can perhaps use this link to verify your calculations.

Thanks… I found I can use the pow function in the “math.h” include!

1 Like