High Altitude Effects
Life in the Sky

Copyright ©2001 by John Cawley III. This document may be freely copied, distributed and archived provided it is copied entire and unmodified and this copyright statement remains intact.

Last updated: 2003-05-04

The current version of this document is obtainable at http://www.Thistlehaven.net/J3. Email comments and questions about this document to j3@pobox.com.

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What Is High Altitude?

Anecdote: I moved to Flagstaff, AZ and soon thereafter was cooking some pudding. The directions on the box gave special high altitude instructions for any place over 3500 feet. It struck me then that Flagstaff was twice as high as that.

So what is "high altitude"?

• Is it when special steps have to be taken while cooking (ie 2500-3500 feet)?
• Is it when potato chip bags look like over-inflated balloons ready to explode and saline solution for contacts siiiiggghhhs the first time you open the container (certainly by 7000 feet)?
• Is it when HAPE and HACE can fill your lungs with fluid or compress your brain against your own skull (!!!)?
• Is it when it really doesn't matter whether the oxygen masks drop down should the airplane cabin lose pressure, as you'll suffocate anyway (since there is not enough air pressure to force even pure oxygen across your lungs and into your bloodstream, at 40_000-45_000 feet)?

Illustration 1: Plate Carée projection (similar to equirectangular) based upon etopo-5 data with 256 shades of grey, each representing 60 meters.

Above is a map showing the elevations of the world (higher=whiter, lower=darker; click on it for the larger version). There are several interesting points to note (some slightly off the subject, of course):

• Florida: the entire state is so close to sea level (the highest point in the state is some 300 feet above sea level) that many browsers will show it the same color as the ocean (this illustration has 256 shades of grey, but many browser / monitor configurations render some of them the same)
  
  Anecdote: When I lived in Georgia, I had a friend that would go fishing in the Gulf of Mexico with a set of those rubber overalls. He would wade out from the shore quite a bit more than a half mile, but the whole area there is so flat that the water never rose above chest level the entire time, so he never got his shirt wet.
• Northeast India, Tibet and Southwest China: note the huge white area between India and China -- this is where the Himalayas and the highest peaks in the world are. The Indian subcontinent has been colliding into Asia for the last 24 million years. This is what happens when continents butt heads.
• Australia: note the dark greys there -- sort of the short-man continent, which it makes up for with its spectacular geology
• Greenland and Antarctica: much of the elevation here comes from the ice sheets, which hold large quantities of the world's fresh water in frozen form

Diagram 2: yellow arrows represent ascents from approximate trailheads / basecamps to summits

Above is a diagram comparing a number of elevations and altitudes. Again, there are a number of salient points to note:

• Florida: again, note Florida's highest point. Florida is actually the very flat top of a mesa that tops almost exactly at sea level

Here is the Gulf of Mexico:

Here is the Gulf of Mexico without water:

Here is a profile view of the Florida peninsula a little north of Port Charlotte:

• High altitude level: 10_000 feet or 3000 meters is generally considered the point above which high altitude sickness can develop in at least mild forms
  
  Nowhere on the east cost of the US does the elevation exceed 10_000 feet, though numerous places west of the central plains do. I had always known that the Appalachian mountains were lower than the Rocky mountains, but never realized the extent until one day that I charted a cross section of the US:
  
  This is a cross-section of the United States at latitude 39N (about the latitude of Washington DC). Note that greater height of the Rockies as compared to the Appalachians. On a side note, the southern half is mostly covered in shadow cast by the higher northlands.

• "Death zone": above 26_000 feet (7900 meters), humans can exist for only a short time
• K2 and Everest: note the difference between these peaks and the other peaks below; the Himalayas represent the spectacular "squishing up" of Asia as India collides into it 
  
  The collision of India into Asia is still continuing -- 1999.11 measurements placed the elevation of Everest at 29_035 feet (8850 meters). This was 7 feet (2 meters) higher than the 1954 measurement. Although margins of error account for some of the difference, a portion of it is likely due to an actual rise. Also, Everest seems to be moving northeast at about 2.5 inches (6 cm) per year.
• Highest altitude for humans without oxygen: note that this line is essentially at the same height as Everest; indeed, current opinion of the scientific community is that Everest happens to be right at the human limit to ascend without oxygen assistance, and that even weather conditions there can affect air pressure enough to make the difference between an unassisted ascent  being possible or not
• Highest altitude for humans with oxygen: this is an altitude above which even a pure oxygen atmosphere will not result in enough oxygen crossing the lungs and saturating the blood in sufficient quantities to sustain life
  
  Nelson Demille and Thomas H Block wrote a fascinating book, Mayday, about a high altitude jet losing air pressure for several minutes before descending by autopilot, after which our hero must deal with "passengers of the living dead", so to speak -- the other passengers had been partially or completely suffocated despite oxygen masks, inducing varying degrees of brain damage.

Physical Effects

TBD

Physiological Effects

TBD

Culinary Effects (ie High Altitude Cooking)

TBD