Re: correct air pressure

["Otto G. Raabe" <ograabe@ucdavis.edu>]

March 26, 1998
Davis, CA

The barometric pressures reported by meteorological services throughout the
United States are not true absolute barometric pressures and cannot be
directly used for any scientific purpose. To avoid public confusion they
are all corrected to the value that they would have been IF the reporting
location had been at sea level. 

Here in Davis, CA, our altitude is only 55 feet above sea level, so the
reported barometric pressures are nearly identical to those I measure with
my mercury barometer (29.9 inches Hg = 76 cm Hg [at 0 C] = 101.3 kPa [SI]).
When I worked in Albuquerque, NM, my laboratory altitude was 5555 feet
above sea level. At that altitude the true barometric pressure was about 62
cm Hg when the weather bureau was reporting 30 inches Hg. Special mercury
barometers have to be constructed to operate at higher altitudes.

Otto
		*****************************************************
		Prof. Otto G. Raabe, Ph.D., CHP
                [President, Health Physics Society, 1997-1998]
		Institute of Toxicology & Environmental Health (ITEH)
		     (Street address: Old Davis Road)
		University of California, Davis, CA 95616
		Phone: 530-752-7754  FAX: 530-758-6140 [NEW AREA CODE]
		E-mail ograabe@ucdavis.edu