Prediction of barometric pressures at high altitudes using model
atmospheres.
West, John B.
Department of Medicine, University of California San Diego, La
Jolla CA 92093-0623
APStracts 3:0283A, 1996.
It would be valuable to have model atmospheres that allow barometric
pressures to be predicted at high altitudes. Attempts to do this in
the past using the ICAO or U.S. Standard Atmosphere model have
brought such models into disrepute because the predicted pressures at
high altitudes are usually much too low. However other model
atmospheres have been developed by geophysicists. The critical
variable is the change of air temperature with altitude, and
therefore model atmospheres have been constructed for different
latitudes and seasons of the year. These different models give a
large range of pressures at a given altitude. For example, the
maximum difference of pressure at an altitude of 9 km is from 206 to
248 torr, that is about 20%. However the mean of the model
atmospheres for latitude 15 degrees (in all seasons) and 30 degrees
(in the summer) predicts the barometric (PB) at many locations of
interest at high altitude very well with predictions being within 1%.
The equation is PB (torr) = exp (6.63268 - 0.1112 h - 0.00149 h2)
where h is the altitude in km. The predictions are good because many
high mountain sites are within 30 degrees of the equator, and also
many studies are made during the summer. Other models should be used
for latitudes of 45 degrees and above. Model atmospheres have
considerable value in predicting barometric pressure at high altitude
if proper account is taken of latitude and season of the year.
Received 5 February 1996; accepted in final form 21 May 1996.
APS Manuscript Number A127-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96