Posted on 05/26/2004 8:08:53 PM PDT by blam
Sky 'fell in' on Everest
By David Derbyshire, Science Correspondent
(Filed: 27/05/2004)
The eight climbers killed on the single deadliest day on Everest may have been victims of the "sky falling in", according to a study.
An analysis of weather patterns in May 1996 suggests the mountaineers died when the stratosphere sank to the level of the summit, 29,000ft above sea level.
The freak weather caused pressure and oxygen levels to plunge within the "death zone" - the area above 26,000ft where the oxygen is extremely thin.
Normally Everest's summit lies just below the atmospheric layer. But on May 10, the day of the disaster, there were two fast-flowing air streams, called jet streaks, moving over the mountain.
Dr Kent Moore, a physicist at the University of Toronto in Canada, believes these would have pushed the stratosphere boundary down with catastrophic results.
During a similar event in 1998 a temporary weather station near the top of Everest recorded a sudden fall in pressure of 16 millibars.
"Such a drop is significant where the air is already very thin," New Scientist reports today. On Everest's summit, it would have been the equivalent to raising the mountain by around 500 yards. It would have instantly cut the amount of oxygen available to the mountaineers by around 14 per cent, Dr Moore believes.
At the summit the air already contains only a third of the oxygen it holds at sea level. The eight were members of a group who were climbing without supplementary oxygen.
Conditions had been good, with the sky free of clouds and the wind light. However, by around 4pm, the "death zone" was engulfed by storms, winds of up to 90mph and temperatures that crashed to minus 40C.
Within 24 hours, eight out of 30 climbers on the mountain were dead.
They included Scott Fischer, from Seattle, and Rob Hall, from New Zealand, the expedition leaders.
The events of May 10 1996 are being turned into a £56 million film to be directed by Stephen Daldry.
NEVER, and I mean never, fly on an airplane!
Other than that, this was so funny to read.
"climbing without supplementary oxygen"
False macho
This is so darn funny.
WOW, a total of 16 millibars!
There are 1023 millibars in 29.92 inches of mercury as a measurement of atmospheric pressure.
Every pilot knows that you will loose 1 inch of mercury for ever 1,000 feet gained in altitude.
Do the math and tell me what 16 millibars is equal to.
Sorry, but I am still laughing too hard.
I read the book "Into Thin Air" about the events mentioned in this article. It is amazing the abuse climbers put on their bodies in climbing Mt. Everest even under ideal conditions. I strongly recommend the book to anyone interested in climbing or learning about how disasters unfold.
I read the book "Into Thin Air" about the events mentioned in this article. It is amazing the abuse climbers put on their bodies in climbing Mt. Everest even under ideal conditions. I strongly recommend the book to anyone interested in climbing or learning about how disasters unfold.
Sorry about the double post. Double clicked the mouse by accident.
Not quite 500 ft.? Be patient with me and explain what you are getting at.
This seems more deadly than a decrease of O2 by 14%.
1" of mercury per 1,000 ft altitude is a rough estimate that is good for low altitudes where a small piston engine plane might fly. I learned it as a way to guesstimate my altitude if my altimeter ever failed; go to full throttle, read the manifold pressure, and subtract that from 30 to get an approximate height above mean sea level.
However, it is obviously a very poor rule of thumb at higher altitudes since it implies that the atmosphere ends at about 30,000 feet ... obviously not even close to accurate. Perhaps you've not seen the stories lately about the massive lighter-than-air craft being proposed to fly at 250,000 feet .
Actually, this story seems very believeable to me ... and not very funny.
I don't know, but since the air pressure at higher altitudes are lower I think there would be some type of exponential factor to be considered as to the force required to move Mercury.
Ok.
At sea level, 29.92 inches of mercury = 1,010 millibars.
Losing 1 in of mercury for every 1,000 feet in altitude (your numbers), then at 29,000 ft (Mt Everest summit):
29.92 inches of mercury - ( 29,000 ft / 1,000 inHg/ft)
29.92 - 29 = .92 inches of mercury at the summit.
Convert .92 inch of mercury to millibars = 31.1548 millibars at the summit.
A loss of 16 millbars from 31 millibars is a 50% loss of pressure.
Given 1/3 oxygen density at the summit and losing 50% yields an equivalent 1/6th of normal oxygen.
Cf. the standard atmosphere calculator at this Properties of the Atmosphere page.
At 29,000 feet the pressure is 31485 Pascal, and at 30,000 feet it is 30090 Pascal, for a difference of 1395 Pascal or about 14 millibars.
16 millibars takes you up to about 30200 ft. - an effective altitude difference of 1200 ft., or 400 yards, by this model.
The drop in partial pressure of oxygen would presumably be proportional to the drop in total pressure, or about 5% . Perhaps the 14% drop in "oxygen available to the mountaineers" involves some sort of physiological model.
16 millibars is around 1 meter in altitude change.
Let me say it on your behalf -- "OOPS! Excuse me."
Oops! Excuse me!
"1013 millibars is equal to 1.013 Pascals."
Google says:
"The standard atmospheric pressure at the Earth's surface of 1013.25 millibars is equal to 101,325 Pascals."
"A Pascal is a unit of force equal to one Newton / m 2 . It is describing the pressure exerted by the ... One millibar is equal to 100 Newtons / m 2"
"1 millibar = 100 Pascals"
"1 hectopascal = 100 pascal = 1 millibar"
Get the picture? You also say:
"16 millibars is around 1 meter in altitude change."
... but here you're not even paying attention yourself. If one atmosphere is 1013 millibars ( correct ) and 1 meter reduces that pressure by 16 millibars, then it's only 63 meters to the edge of space!
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