Re: Speed of sound at altitude and temp

[David Dockstader <DRDOCK00@UKCC.UKY.EDU>]

The formula Brian gives addresses temp, but not altitude.
I looked up speed of sound in the index of my CRC Handbook of Chem & Physic
(48th ed, hopefully in newer ed too) and found a neat graph of the speed of
sound vs altitude for the real earth (I assume this is empirical but am not
sure of this) At 35,000 ft it is 335m/s.  Interesting related graphs are
Mean free path vs altitude and Collision Frequency vs Altitude.


On Sat, 12 Jul 1997 12:19:15 brian whatcott said:
> At 09:48 7/11/97 -0400, you wrote:
>
> > I was curious about what the speed of sound would be at 35,000 feet annd
> > -62 degrees Fahrenheit.  Is there a convenient table or formula that
> > would let me figure that out. ...
> >        Jim Braunsdorf
> Enc Brit ( 14th edition, "sound") offers this empirical formula:
> c = 331.3 x root(1 + t/273)
>
> c in meters/sec, temp in degC
>
> This is c = 741 x root(0.935 + 0.002t)
>
> c in mph, t in degF
>
> It works reasonably well for dry air not far from ambient.
>
> Regards
> brian whatcott <inet@intellisys.net>
> Altus OK