Talk:Land and water hemispheres

Merge

I boldly merged the articles Water hemisphere and Land hemisphere as they were essentially talking about the same topic. --LukeSurl ^{t c} 18:01, 18 February 2014 (UTC)

OPPOSE Since the other four hemispheres (Northern, Southern, Western, and Eastern) all have their own articles, I reckon Land and Water hemispheres should have their own articles as well. 120.16.160.49 (talk) 01:59, 10 July 2017 (UTC)

There is nothing to talk about regarding these hemispheres other than their definition. These hemispheres aren't concepts that are ever actually used (unlike the NSEW ones). It's borderline whether these are even notable at all, and having separate articles for land and water would simply duplicate this content unnecessarily. --LukeSurl ^{t c} 20:31, 10 July 2017 (UTC)

That 7/8 figure generates a discrepancy

The 'land hemisphere' if it contained exactly 7/8 of the land surface (87.5%) works out to 51% land. (130 000 000 km2) But the included comment is that it is still more than 50% water, which suggests that it is closer to 85% of the total land than 87.5%. — Preceding unsigned comment added by 174.73.22.113 (talk) 13:46, 28 May 2014 (UTC)

I believe it's a rounding issue, the figures of eighths are only approximate (the text actually says "just under seven-eighths"). Would need to check source to be sure, but I reckon very few people will be able to access the full text of that paper for free.--LukeSurl ^{t c} 14:57, 28 May 2014 (UTC)

A clue is found in the differentiation of the earth's surface into water, land and polar ice cap. If the 9% of earth's surface that is Antarctica is excluded from the total surface area of the world, that is what allows the 7/8 figure to come out right. If all of Antarctica is included in the world's land area, the figure is that only 4/5 of the world's land area is in the land hemisphere. This is based on my calculations using a program that examined an equal-area map of the world.

I used a Gall equal-area map of the world at

http://www.progonos.com/furuti/MapProj/Normal/ProjCyl/ProjCEA/projCEA.html

which uses the image

http://www.progonos.com/furuti/MapProj/Normal/ProjCyl/ProjCEA/Img/mp_EqACyl-s75-p45.png

which shows water in blue and land in a yellow-green. There were about 1300 pixels neither color, out of 72792 on the map altogether, used for grid lines, but even this small number come out of both land and water proportionately and the same with hemispheres. For comparison, it identifies 29.3% of the counted (land or water) pixels as being land, in agreement with accepted figures of 29.1% or 29.2%.

I counted 20951 land pixels altogether, with 16686 of them falling within a 90° radius of either of the center points given in the text--that is regardless of which of the points is used. The distance was based on applying spherical trig to the latitude based on the arcsine of the proportional distance from the mapping of the equator. That amounts to only 79.6% or about 80% of the earth's land mass falling within the land hemisphere or 4/5, rather than 7/8. But if the area of Antarctica (9% of landmass based on the Continents article in Wikipedia) is subtracted from the total landmass, the 7/8 becomes correct.

This also suggests that the full extent of Antarctica was excluded from the total land area of the earth rather than just the smaller part that was apparently counted as "ice cap". — Preceding unsigned comment added by Chasklue (talk • contribs) 19:43, 8 June 2018 (UTC)

Some figures, converted to millions of square km:

Land: 150 (including 14 for Antarctica)

Land in land hemisphere: 119

Water: 360

Water in water hemisphere: 223 (leaving 32 for land including Antarctica's 14)

Total of Earth: 510

A hemisphere is 255 million km; 119/255 or 47% of land hemisphere is land.

The 119 of land that are in the land hemisphere account for 119/(119+32) or about 80% of the total land.

If Antarctica is excluded from the total land the 119 million km accounts for 119/(119+18) or about 87% of the total land. — Preceding unsigned comment added by Chasklue (talk • contribs) 21:14, 8 June 2018 (UTC)

Based on the above, the paragraph stating "The Water Hemisphere has only about one-eighth of the world's land,[1] including Australia, New Zealand, Antarctica, Hawaii, the Maritime Southeast Asia, and the Southern Cone of the Americas." is discrepant. The 1/8 value is dependent on not counting Antarctica as land. When it's included, the Water Hemisphere contains fully 1/5 of the world's land area--it's the 5% (14/255) of the hemisphere that's ice cap rather than land or water and would be 7.5% of the world's land area. — Preceding unsigned comment added by Chasklue (talk • contribs) 19:47, 9 June 2018 (UTC)

Examining the azimuthal equal-area maps in the article itself verifies the figures.

The Land Hemisphere map has 1,587,411 pixels within the black boundary circle, of which 740,754 are white (land), and the Water Hemisphere map has 1,585,342 pixels within the circular boundary, of which 172,207 are white (land).

Altogether land constitutes 28.8% of the pixels. Land also constitutes 46.6% of the Land Hemisphere and the land in the land hemisphere constitutes 81.1% of the total land pixels. This is the limit of accuracy given the 3-significant figure agreement in total pixel count between the two maps.

The article itself has been changed accordingly. — Preceding unsigned comment added by Chasklue (talk • contribs) 18:04, 10 June 2018 (UTC)

Hello Chasklue. You calculations here are interesting, however we cannot include them in the article as this would violate Wikipedia:No original research, one of Wikipedia's key policies. --LukeSurl ^{t c} 15:47, 11 June 2018 (UTC)

While my first research was on a Gall projection map found elsewhere, I did not post the revision onto the article itself until I actually only did a pixel count on the Lambert equal area maps already found within this Wikipedia article. Can this article itself (that is, the illustrative maps in it) be considered a source? Could the Gall projection map found elsewhere be considered a source, and be footnoted. It would seem a shame to let the fiction that only 1/8 of the world's land area is found in the water hemisphere become a quasi-fact like the trope that we only use 10% of our brains. I do not have access to the cited reference 1, but even the existing article states that the water hemisphere contains 5% polar ice cap to make up the 100% of that hemisphere, so reference 1 must have made the exclusion of Antarctica explicit, and the current version that claims Antarctica is included in the land area must be erroneous in its use of the cited material. — Preceding unsigned comment added by Chasklue (talk • contribs) 16:41, 11 June 2018 (UTC)

I shall use figures from reference 2 (Berget), which fortunately is not behind a pay wall, and publish when I educate myself on the table format used in Wikipedia. Berget seems to be more authoritative on the subject than Boggs, who was more interested in showing different types of dividing the earth into hemispheres than in describing this specific division. I managed to find a copy of Boggs' paper on microfilm at the local university library and he devotes only 1 page out of a 10 1/3 page paper to the land/water hemispheres; and within that section he specifically excludes Antarctica (In the caption for Fig. 1, available even before the pay wall, he states, "About 6 per cent of the world's population lives here [water hemisphere] on 12 per cent of the world's land area (excluding Antarctica).", so I am right now going to reinstate that portion of what I had previously said. The portion giving the actual percent, including Antarctica will come in a few days, when I can cite Berget's figures. — Preceding unsigned comment added by Chasklue (talk • contribs) 11:16, 13 June 2018 (UTC)

Population hemisphere

I was interested in the concept of, the hemisphere of the Earth that contains the highest population. I thought it would have have been called population hemisphere if anything. I couldn't find any on Wikipedia about it, but after searching the web, I found this page. That page calls it the human hemisphere, and it's very similar in position to the land hemisphere as one would expect, but not exactly aligned. The centre of this hemisphere contains 92.9% of the world population and is centred on western Switzerland. I thought I would share it here in case anyone else was curious, as I looked here first hoping to find something on this. Someone could use this or other sources to start an article on it if they wanted, it's mildly interesting but not very notable, but then again it's about the same level of notability as land and water hemisphere so, maybe?  Carlwev  11:59, 10 December 2016 (UTC)

Hi Carlwev. Talk:Hemispheres_of_the_Earth would probably be a better location for this discussion. Ultimately, having an article on this topic would depend on whether there were multiple decent sources discussing the concept. --LukeSurl ^{t c} 15:06, 12 December 2016 (UTC)

Carlwev: I've added human hemisphere info into this article. It's coincidence with the Land hemisphere is interesting. Thank you for finding this. --LukeSurl ^{t c} 16:13, 12 December 2016 (UTC)

The population hemisphere could probably have its own article as well as the other less populated side. But what would the hemisphere with the least population be called? Redgro (talk) 20:10, 29 September 2017 (UTC)