NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Table A4 + elevation?
From: Paul Hirose
Date: 2003 May 2, 09:53 -0700
From: Paul Hirose
Date: 2003 May 2, 09:53 -0700
George Huxtable wrote: > > Vaguely remembering (or maybe misremembering?) the density (relative to > water) of air as 1/830 and of Mercury as 13.6, it seems to me that at > Doug's height of 2100 ft. the atmospheric pressure will be reduced by 7.5% > below what it is at ground level. (Somebody please check!) If that's > correct, then the local pressure will reduce to 935 millibars, compared > with its "standard" sea-level value of 1010. That takes it well outside the > realms of the diagram that goes with table A4, which goes no further down > than 970. At 2100 feet in the 1976 U.S. Standard Atmosphere, pressure is .92641 of sea level. Multiplying that by 1010 mb gives 935.7 mb. Pretty good estimate, George.
