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alisoncc
20th Jul 2011, 07:58
Auntie Beeb are reporting that Nepal is re-measuring Mt Everest

BBC News - Nepal to re-measure Mount Everest to end China row (http://www.bbc.co.uk/news/world-south-asia-14213137)

Beside the obvious requests ' Who's going to hold the end of the tape", where do they measure it from.

Sea Level - but the sea level where? The last time I looked Mt Everest was an awfully long way inland. And as the article would suggest that the Chinese say it should be the height of the rock, whereas the Nepalese say it should be the snow height, whether the tide is in or out could make a difference too.

Keef
20th Jul 2011, 08:58
I don't know why they're arguing about it. It's a long way up - further than I'm ever going to walk!

sitigeltfel
20th Jul 2011, 09:00
If you saw the Earth documentary last night, the Hamster explained it was growing by 5mm per year and was now a foot taller than when it was first scaled. Make your mind up, metric or imperial!

MadsDad
20th Jul 2011, 09:07
I remember being told when young (and it has been on QI since so it must be right) that when the height was originally surveyed the height was measured at exactly 29,000 feet. The surveyor thought that no-one would believe this, far too 'round' a number, so added the 29 feet to make it sound better.

tony draper
20th Jul 2011, 09:09
Imperial of course it were named after a Englishman.:rolleyes:
Incidently it should be pronounced "Eve-er rest",as that is how the good Sir George pronounced his family name.
:)

G-CPTN
20th Jul 2011, 09:13
the height was measured at exactly 29,000 feet
The figure that springs to my mind was 29,002 ft from the announcement in June 1953 when Edmund Hillary and Sherpa Tensing first reached the top. I think that that was later amended to 29,029 ft.

I believe that the Earth isn't a perfect sphere, or even a perfect oblate spheroid - for a start there are lumps and bumps (as well as dimples), so establishing a baseline for accurate measurement of the height of a mountain might be arbitrary.
An aneroid barometer is subject to atmospheric pressure variations.
A GPS device might provide an accepted figure - but then the heights of other mountains would need to be measured against the same system.

tony draper
20th Jul 2011, 09:19
The underlying base of Everest floats in the Earths mantle like a cork with a turd sitting on it floating in a puddle so when bits wear off the top, ie the turd, less weight is pressing down and the entire edifice rises a bit,tiz called Isostatic equlibrium.
You can tell one once read a book.
:rolleyes:

MadsDad
20th Jul 2011, 09:31
like a cork with a turd sitting on it floating in a puddle

Ah, the poetry of the English language.

G-CPTN
20th Jul 2011, 09:31
In 1856, the Great Trigonometric Survey of British India established the first published height of Everest, then known as Peak XV, at 29,002 ft (8,840 m).
The elevation of 8,848 m (29,029 ft) was first determined by an Indian survey in 1955, made closer to the mountain, also using theodolites. It was subsequently reaffirmed by a 1975 Chinese measurement 8,848.13 m (29,029.30 ft). In both cases the snow cap, not the rock head, was measured.
In May 1999 an American Everest Expedition, directed by Bradford Washburn, anchored a GPS unit into the highest bedrock. A rock head elevation of 8,850 m (29,035 ft), and a snow/ice elevation 1 m (3 ft) higher, were obtained via this device.
On 9 October 2005, after several months of measurement and calculation, the Chinese Academy of Sciences and State Bureau of Surveying and Mapping officially announced the height of Everest as 8,844.43 m (29,017.16 ft) with accuracy of 0.21 m (0.69 ft). They claimed it was the most accurate and precise measurement to date. This height is based on the actual highest point of rock and not on the snow and ice covering it. The Chinese team also measured a snow/ice depth of 3.5 m (11 ft), which is in agreement with a net elevation of 8,848 m (29,029 ft).
From:- Mount Everest - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Mount_Everest#Measurement)

tony draper
20th Jul 2011, 09:40
I seem to recall there is a limit to how high a mountain can become due to the Earth Gravity dont recal what it is now but frinstance we could never have a hill ten miles high,nature wont allow it.
:)

G-CPTN
20th Jul 2011, 09:46
List of highest mountains - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/List_of_highest_mountains#The_list)

Exascot
20th Jul 2011, 09:51
...the Chinese say it should be the height of the rock, whereas the Nepalese say it should be the snow height.


For once I think that I will support the Chinese on this one.

However the elevation has to be defined as AMSL. They tell us that the oceans are rising every year. Surely that means that the mountains are actually shrinking :confused:

arcniz
20th Jul 2011, 10:31
http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/Geoid_height_red_blue.png/350px-Geoid_height_red_blue.png

The reasonable thing would be to reference the elevation to the global GEOID map, which is recently updated and can be readily correlated with Sea-level and other heights and depths throughout the planet.

Discussion of Geoid can be found HERE (http://en.wikipedia.org/wiki/Geoid).

The most recent Geoid update has been produced this year by ESA. A pic with exaggerated proportions looks like this:

http://news.softpedia.com/newsImage/ESA-Releases-GOCE-s-Geoid-Model-2.jpg/

http://i1-news.softpedia-static.com/images/news2/ESA-Releases-GOCE-s-Geoid-Model-2.jpg

Rossian
20th Jul 2011, 10:49
...when did they stop using a bar in the harbour wall at Newlyn, Cornwall as the ref point for "sea level"? And did they have permission??

The Ancient Mariner

G-CPTN
20th Jul 2011, 10:56
Mean sea level is not constant over the surface of the Earth. For instance, mean sea level at the Pacific end of the Panama Canal stands 20 cm (7.9 in) higher than at the Atlantic end. From:- Sea level - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Sea_level#Difficulties_in_utilization)http://www.qtl.co.il/img/copy.pnghttp://www.google.com/favicon.ico (http://www.google.com/search?q=Mean%20sea%20level%20is%20not%20constant%20over%20t he%20surface%20of%20the%20Earth.%20For%20instance,%20mean%20 sea%20level%20at%20the%20Pacific%20end%20of%20the%20Panama%2 0Canal%20stands%2020%20cm%20%287.9%20in%29%20higher%20than%2 0at%20the%20Atlantic%20end.%20%5B/quote%5DFrom:-%20Sea%20level%20-%20Wikipedia,%20the%20free%20encyclopedia)http://www.qtl.co.il/img/trans.png

Storminnorm
20th Jul 2011, 11:07
Them Chinese are fiendish!!!
Who else would DREAM of having a 30,000 ft tapemeasure!!!!

FLCH
20th Jul 2011, 11:37
Let's not forget to include that Hillary Clinton claimed to have been named after Sir Edmund's surname, six years after she was born.... ;)

SpringHeeledJack
20th Jul 2011, 12:22
Whilst I can see the logic in measuring the upper limit of the rock as the height, the simple fact is that the 'snow' on top is incredibly compacted and to all intents and purposes solid and permanent. Perhaps it's a bit like building a wooden shed in yer garden and because it's deemed as a temporary structure, it doesn't need planning permission, but is as good as permanent :p If this starts a precedent, a good many mountains around the planet are going to be revised altitude wise by the surveyors and cartographers.



SHJ

G-CPTN
20th Jul 2011, 12:37
List of mountains in Greenland - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/List_of_mountains_in_Greenland)

Carry0nLuggage
20th Jul 2011, 12:59
Sea level II

a bar in the harbour wall at Newlyn, Cornwall

Does this mean we have to unscrew this bar and lend it to Nepal? :confused:

Exascot
20th Jul 2011, 13:11
The reasonable thing would be to reference the elevation to the global GEOID map

Geoid - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Geoid) Don't worry about the formulas - I didn't :confused:

That is interesting so do we know if they do this or not. Never heard of it before.

Sailor Vee
20th Jul 2011, 13:42
a bar in the harbour wall at Newlynshouldn't 'in' be replaced with 'on'? That way we'll know whether they was pished when they made the decision.

radeng
20th Jul 2011, 13:57
You could build a bar into a wall, in the same way as the 'Hole in the Wall' at Waterloo is built into a railway viaduct.

G-CPTN
20th Jul 2011, 14:03
There is a bar called the Hole in the Wall in Bristol, but I think it is a few feet above MSL.

Rossian
20th Jul 2011, 16:07
....I sent an e-mail to the harbour master at Newlyn to confirm my suspicions. He replied (or his minion did) and said that until a few years ago the chart datum was measured at the end of the Stone Pier every 15 mins, all day, every day.

The Ancient Mariner

MadsDad
20th Jul 2011, 16:19
Does this mean we have to unscrew this bar and lend it to Nepal?

Well please let me know when this is going to happen as I don't want to be supping in there at the time. :zzz: