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Al Barkamps
Social climber
Red Stick
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The barometric pressure at a given altitude is on average less at the poles than it is at the equator.
really? You mean sea level is lower at the poles than it is at the equator? That explains why it's further to walk out to the water in Anchorage than Mancora....
Sorry Reilly, I was under the impression that you knew the difference between breathing at altitude and flying at altitude.
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matisse
climber
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That's all I was implying - that at the same altitude as the temp rises
you get less O2 per lungful, just like an airplane engine unless it is
turbocharged. :-)
NO you don't
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matisse
climber
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really? You mean sea level is lower at the poles than it is at the equator?
the atmosphere is thicker at the equator than the poles for a variety of reasons. This means for a given elevation the barometric pressure is, on average, higher.
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matisse
climber
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here's the citation below. the full text should be free.
West got really interested in this because he had predicted, based on analysis of available data (some of which he had collected during the silver hut expedition of 1960-1961) that it would be impossible to climb Everest without supplemental oxygen. Then in 1978 Messner and Habler went out and did it leaving West to figure out how.
In 1981 he mounted AMREE the American Medical Research Expedition to Everest which culminated in Chris Pizzo getting barometric pressure measurements and an alveolar gas sample on the summit. The PO2 was higher than expected, and the PCO2 was astonishingly low (7.5 torr if memory serves, normal is 40) indicating a huge amount of hyperventilation. Importantly barometric pressure was higher than expected. That led to this piece of research:
J Appl Physiol (1985). 1996 Oct;81(4):1850-4.
Prediction of barometric pressures at high altitude with the use of model atmospheres.
West JB.
Abstract
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 Organizations 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., approximately 20%. However, the mean of the model atmospheres for latitude of 15 degrees (in all seasons) and 30 degrees (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), were h is the altitude in kilometers. 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 PB at high altitude if proper account is take of latitude and season of the year
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