The Physics
Factbook
An encyclopedia of scientific essays

Pressure on Earth, Lowest

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Bibliographic Entry Result
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Standardized
Result
Barometer. World Book Online Americas. AOL, 2001. "For example, the average air pressure drops from 1,013 mb at sea level to about 700 mb at an altitude of 10,000 ft and to about 300 mb at 30,000 ft." 30 kPa
Sengupta, Debangsu, Wisselinkm Simon, Chengm Yain. Himalayas- Where the Earth meets the Sky. ThinkQuest. 1997 "The atmospheric pressure at the summit of Mt. Everest is about a third that at sea level" 33.7 kPa
CRC Press. Handbook of Chemistry and Physics. 61st Ed. 1981. [Using a Pressure v. Altitude chart, 29,000 meters high was shown to have 30 kPa.] 30 kPa
Dempsey, Dave. Atmospheric Pressure and Imaginary Air Columns. San Francisco State University. Spring 2001. "Levels in the atmosphere. The summit of Mt. Everest, the highest elevation on earth, where the pressure averages around 300 mb." 30 kPa

Located at 28 degrees north, Mount Everest has been recorded for having the highest elevation on earth. In the 1950s, the height was recorded at 29,000 feet high. However, this number was slightly wrong. Using the technology of radar and satellites, the height of Mount Everest has been shown to be 29,028 feet high. The summit of Mount Everest has an average pressure around 30 kPa. Why is pressure on top of Mount Everest a factor for mountaineers to consider before they embark on an adventure of a lifetime? Because so few climbers would be able to reach the summit by breathing natural air.

The pull of air by earth's gravitational field was discovered in the Seventeenth Century by pioneering scientists. Evangelista Torricelli once said, "We live submerged at the bottom of an ocean of the element air."This pull is called atmospheric pressure. Torricelli went to develop the mercury barometer, which is an instrument used to measure atmospheric pressure. A barometer also measures variations in atmospheric pressure.

As altitude increases, the air becomes thinner, the density of air decreases, and the pressure of the air decreases as well. As the air becomes becomes less dense, the air contains less gases per unit of volume, and therefore less oxygen. This information is used by physiologists to predict the deprivation of oxygen a mountaineer will face at high altitudes. Atmospheric pressure is affected by other factors. Water molecules have less mass than all other molecules in the air so as the water vapor increases, the density of the air will decrease. Temperature affects the density of the air, so as the temperature increases and the density decreases, the atmospheric pressure will descend.

So, what causes such a death toll on top of Mount Everest? Mountaineers are affected by altitude sickness, frostbite, hypothermia, and snow blindness. As mountaineers climb the mountain, the climbers bodies are being deprived of oxygen because of the atmospheric pressure. The body overcompensates for this by breathing more vigorously. This causes the body to exhale too much carbon dioxide which eventually upsets the bloods pH level. The blood becomes more alkaline than usual and the mountaineer becomes nauseated and dizzy.

Jared Goldberger -- 2001