Prediction of barometric pressures at high altitudes with the use of model atmospheres

Abstract

West, John B. Prediction of barometric pressures at high altitudes with the use of model atmospheres. J. Appl. Physiol. 81(4): 1850–1854, 1996.—It would be valuable to have model atmospheres that allow barometric pressures (Pb) to be predicted at high altitudes. Attempts to do this in the past using the International Civil Aviation Organization or United States 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, i.e., ∼20%. However, the mean of the model atmospheres for latitude of 15° (in all seasons) and 30° (in the summer) predicts Pb at many locations of interest at high altitude very well, with predictions within 1%. The equation is Pb(Torr) = exp (6.63268 − 0.1112 h − 0.00149 h2), where h is the altitude in kilometers. The predictions are good because many high mountain sites are within 30° of the equator and also many studies are made during the summer. Other models should be used for latitudes of 45° and above. Model atmospheres have considerable value in predicting Pb at high altitude if proper account is taken of latitude and season of the year.