# The Earth's three highest mountains - by three definitions

#### steve_bank

##### Contributor
Diapers? Those astronaught diapers should be sturdy enough.

Hilary and Norgay did the Everest first ascent in the 50s with crude equipment and clothes by today's standards. I don't think they used O2.

#### lpetrich

##### Contributor
I'd earlier calculated the geopotential height as
$$\displaystyle{ \frac{g}{g_0} h }$$

But that is a first-order approximation, and I must be more careful. The gravitational potential is (-G*M/r) for gravitational constant G, mass M, and distance from the center r. Adding h to r and expanding in a series in h gives us
$$\displaystyle{ \frac{g}{g_0} h - \frac{GM}{r^3} h^2 + \text{higher-order terms, overall O(h**3), nonspherical O(h**2)} }$$

For Ötzi, this additional correction is -1.65 m, and for Everest, -12.29 m, giving 3208 m and 8823.09 m.

#### steve_bank

##### Contributor

By setting 29.92 inHg/1013.4 mb, the altimeter will immediately read pressure altitude. If no altimeter is handy, a simple math formula will provide the same answer. Pressure altitude = { (Sea Level Pressure – 29.92) x 1,000} + true altitude (or field elevation if on the ground) Pressure Altitude Versus Density Altitude

In aviation, pressure altitude is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the atmosphere is 29.921 inches of mercury (1,013.2 mbar; 14.696 psi) as measured by a barometer.[2] It indicates altitude obtained when an altimeter is set to an agreed baseline pressure under certain circumstances in which the aircraft’s altimeter would be unable to give a useful altitude readout. Examples would be landing at a high altitude or near sea level under conditions of exceptionally high air pressure. Old altimeters were typically limited to displaying the altitude when set between {\displaystyle 950~\mathrm {mb} }
and {\displaystyle 1030~\mathrm {mb} }
. Standard pressure, the baseline used universally, is {\displaystyle 1013.25}
hectopascals ({\displaystyle \mathrm {hPa} }
), which is equivalent to {\displaystyle 1013.25~\mathrm {mb} }
or {\displaystyle 29.92}
inches of mercury ({\displaystyle \mathrm {inHg} }
). This setting is equivalent to the atmospheric pressure at mean sea level (MSL) in the ISA. Pressure altitude is primarily used in aircraft-performance calculations and in high-altitude flight (i.e., above the transition altitude).

The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the density altitude is the air density given as a height above mean sea level. The density altitude can also be considered to be the pressure altitude adjusted for a non-standard temperature.

Both an increase in the temperature and a decrease in the atmospheric pressure, and, to a much lesser degree, an increase in the humidity, will cause an increase in the density altitude. In hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.

In aviation, the density altitude is used to assess an aircraft's aerodynamic performance under certain weather conditions. The lift generated by the aircraft's airfoils, and the relation between its indicated airspeed (IAS) and its true airspeed (TAS), are also subject to air-density changes. Furthermore, the power delivered by the aircraft's engine is affected by the density and composition of the atmosphere.

#### T.G.G. Moogly

Diapers? Those astronaught diapers should be sturdy enough.

Hilary and Norgay did the Everest first ascent in the 50s with crude equipment and clothes by today's standards. I don't think they used O2.

They did. The first recorded ascent without supplemental oxygen was Messner in 1978.

#### steve_bank

##### Contributor
Sounds like climbing stairs up a tall building breathing trough a straw with a bag over your head.

#### lpetrich

##### Contributor
How Nirmal Purja scaled the world's tallest peaks in record time
“Don’t be afraid to dream big,” Nirmal “Nims” Purja says in the opening voiceover of the new Netflix documentary “14 Peaks: Nothing Is Impossible,” out now. Purja, a 38-year-old mountaineer, didn’t dream big so much as he dreamed tall.

The doc chronicles his attempt to climb all 14 peaks in the world that are over 8,000 meters in seven months. The previous record for such a feat was seven years. Climbing a single eight-thousander is a huge endeavor that can take months, inflict a significant toll on the body and requires a good degree of luck in terms of weather and conditions.

“Anything above 8,000 meters is in ‘the death zone,’ ” filmmaker and fellow mountaineer Jimmy Chin, known for the Oscar-winning climbing documentary “Free Solo,” says in the movie. “You’re breathing about one-third of the amount of oxygen that you would at sea level.”
14 Highest Mountains in the World - Project Base8000
Climbing to the summit of all 14 eight-thousanders is regarded as a mountaineering challenge and as at 2019 only 40 mountaineers have achieved this. The Himalayan Database captures many of these ascents.

...
October 2019 update: Nirmal ‘Nims’ Purja has just broken the world record for summiting these mountains in record time. His ‘Project Possible‘ achieved this Herculean feat in 6 months and 6 days! We were lucky to meet Nims on our trek to Cho Oyu Advance Base Camp.

The Himalayan Database, The Expedition Archives of Elizabeth Hawley

8000ers.com, Statistics, News and Stories about the 14 highest mountains of the world

Everest - The eight-thousanders - shows 3D models of these mountains in webpages

#### lpetrich

##### Contributor

The highest ones are in a strip between the Indian subcontinent and Central Asia. From west to east, Hindu Kush - Pamirs - Karakoram - Himalayas / Transhimalayas - Hangduan. All 14 peaks are in this strip, including champion Mt. Everest at 8848 m.

They are the result of the Indian plate running into the Eurasian plate.

North of the Himalayas is the Tibetan Plateau, and north of it is the Kunlun Mountains (highest: Liushi Shan, 7167 m). Further north is the Tarim Basin, a low spot, and then the Tian Shan mountains (highest: Jengish Chokusu, 7439 m)

These mountains are part of the a.k.a the Alpine-Himalayan orogenic belt or the Tethyan orogenic belt. Its western part is the produced by the African and the Arabian plates running into the Eurasian plate.

This is a long strip of mountain ranges that extends along the southern border of the Eurasian plate, extending southern Europe - northern Middle East - southern Central Asia - Southeast Asia - western and southern Malaysia / Indonesia

-

Outside of that long strip, the mountain ranges with the highest mountains are in the a long strip of mountain ranges that extends western North America - Central America - western South America. Its highest peak is Aconcagua in the Andes, at 6962 m. It was produced by the collision of the Pacific plate and some smaller plates on one side, and the Atlantic plate and some smaller plates on the other side.

#### steve_bank

##### Contributor
8000 feet is like climbing about 10 Empire Ste Buildings.