Altitude and torr

[Vipers]

OK guys, I have given up googling, maybe someone here knows what I need.

I want to convert metres of altitude, ie 200 metres above sea level, to torr, ie mmhg, ie millibars.

I can find a site where you enter a fixed figure and it shows the answer, (for example enter 400 meters above sea level, and it shows 727 millibars, or torr),but I just cannot find the formulae, with the formula, I can generate an exel spreadsheet to produce a chart.

C'mon guys, show me as usual this is THE site for all knoweldge? (hopefully)

[MarkwG]

Can I just check: are you talking about a method of measuring the distance above the planet by using atmospheric pressure? I ask because you're using some terms I understand but others I have no clue about.

[Vipers]

OK, what I am trying to achieve, is to be able to put a programme in exell, showing metres above sea level, ie 200 msw, and the corresponding pressure in millibars, or mmhg, or torr, (all one and the same).

Unlike converting metres to feet by multiplying by 3.281, it is what I think they call it expotential, (Not sure that means anyway), the fact I have found a site where I can put in a distance in mtrs above sealevel, ie 200 and get a pressure in millibars of 743, or at 3000 metres a pressure of 537 millibars, there must be a formulae to calculae it.

Thats what I am after, jus the formulae to calculate pressure in mmhg, or millibars at altitude.

[tubbystu]

I'm a bit confused as to how height above sea level is directly convertible to a pressure as a standard calculation without additional parameters, but hey if its anywhere try here;

Convert just about anything to anything else

This is the pressures page

[Vipers]

tubbystu said:

I'm a bit confused as to how height above sea level is directly convertible to a pressure as a standard calculation without additional parameters, but hey if its anywhere try here;

Convert just about anything to anything else

This is the pressures page

Thanks for that, but what I want is the formulae. If you were to produce an excell work sheet showing Feet of seawater into Metres, you would just use 1 mtr = 3.281 feet of seawater, but as you go up the way, it is not that simple.

Basically as you ascend up a mountain, the air gets thinner, the barometric pressure reduces, at sea level its 760 millibars of pressure, at 1600 metres its 643 millibars, and at 3000 metres its 537 millibars, so there must be a formulae to calculat this out.

As I said I have found a site where you can enter a single altitude in metres, and it shows the corresponding pressure in millibars, but what I want is the formulae to work it out.



P.S. Anyway off to bed, early shift tomorrow, will log in again tomorrw night, thanks for input so far, cheers guys.

[RDE]

I don't know how it's done, but in my degree we always used a Standard Atmosphere Table:

http://www.digitaldutch.com/atmoscalc/table.htm

Like most things in engineering though, it puts the standard pressure setting at sea level, so if the QNH was anything other than 1013 you'll get the wrong pressure for a given altitude.

At work we use 1 mb = 28 ft, which is rounded, so once you extrapolate that you might get pretty innacurate results.

[AlexB]

I don't know if these pages help...
http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic...
http://en.wikipedia.org/wiki/Atmospheric_pressure#...

[Overhaulin]

This should help
http://wapedia.mobi/en/Barometric_formula.

googled atmospheric pressure formulae