Topic: Geography

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๐Ÿ”— River Ranking by Water Flow Rate

๐Ÿ”— Lists ๐Ÿ”— Geography ๐Ÿ”— Rivers

This article lists rivers by their average discharge measured in descending order of their water flow rate. Here, only those rivers whose discharge is more than 2,000ย m3/s (71,000ย cuย ft/s) are shown, as this list does not include rivers with a water flow rate of less than 2,000ย m3/s (71,000ย cuย ft/s). It can be thought of as a list of the biggest rivers on earth, measured by a specific metric.

For context, the volume of an Olympic-size swimming pool is 2,500 m3. The average flow rate at the mouth of the Amazon is sufficient to fill more than 83 such pools each second. The average flow of all the rivers in this list adds up to 1,192,134 m3/s.

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๐Ÿ”— Zone of Death (Yellowstone)

๐Ÿ”— Law ๐Ÿ”— Geography

The Zone of Death is the name given to the 50ย sqย mi (129.50ย km2) Idaho section of Yellowstone National Park in which, as a result of a purported loophole in the Constitution of the United States, a criminal could theoretically get away with any crime, up to and including murder.

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๐Ÿ”— Island of California

๐Ÿ”— California ๐Ÿ”— Mexico ๐Ÿ”— Geography ๐Ÿ”— Mythology ๐Ÿ”— Islands

The Island of California refers to a long-held European misconception, dating from the 16th century, that the Baja California Peninsula was not part of mainland North America but rather a large island (spelled on early maps as Cali Fornia) separated from the continent by a strait now known as the Gulf of California.

One of the most famous cartographic errors in history, it was propagated on many maps during the 17th and 18th centuries, despite contradictory evidence from various explorers. The legend was initially infused with the idea that California was a terrestrial paradise, like the Garden of Eden or Atlantis.

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๐Ÿ”— Gravity Hill

๐Ÿ”— Geography ๐Ÿ”— Mountains

A gravity hill, also known as a magnetic hill, mystery hill, mystery spot, gravity road, or anti-gravity hill, is a place where the layout of the surrounding land produces an optical illusion, making a slight downhill slope appear to be an uphill slope. Thus, a car left out of gear will appear to be rolling uphill against gravity. There are hundreds of recognized gravity hills around the world.

The slope of gravity hills is an optical illusion, although sites are often accompanied by claims that magnetic or supernatural forces are at work. The most important factor contributing to the illusion is a completely or mostly obstructed horizon. Without a horizon, it becomes difficult to judge the slope of a surface as a reliable reference is missing. Objects which one would normally assume to be more or less perpendicular to the ground, such as trees, may actually be leaning, offsetting the visual reference.

A 2003 study looked into how the absence of a horizon can skew the perspective on gravity hills by recreating a number of antigravity places in the lab to see how volunteers would react. As a conclusion, researchers from Universities of Padova and Pavia in Italy found that without a true horizon in sight, landmarks such as trees and signs actually played these tricks on the human brain.

The illusion is similar to the Ames room, in which objects can also appear to roll against gravity.

The opposite phenomenonโ€”an uphill road that appears flatโ€”is known in bicycle racing as a "false flat".

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๐Ÿ”— Null Island

๐Ÿ”— Computing ๐Ÿ”— Geography

Null Island is a name for the area around the point where the prime meridian and the equator cross, located in international waters in the Gulf of Guinea (Atlantic Ocean) off the west African coast. In the WGS84 datum, this is at zero degrees latitude and longitude (0ยฐN 0ยฐE), and is the location of a buoy. The name 'Null Island' serves as both a joke based around the suppositional existence of an island there, and also as a name to which coordinates erroneously set to 0,0 are assigned in placenames databases in order to more easily find and fix them. The nearest land is a small islet offshore of Ghana, between Akwidaa and Dixcove at 4ยฐ45โ€ฒ30โ€ณN 1ยฐ58โ€ฒ33โ€ณW, 307.8ย nmi (354.2ย mi; 570.0ย km) to the north.

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๐Ÿ”— Agloe, New York

๐Ÿ”— Geography ๐Ÿ”— New York (state) ๐Ÿ”— New York (state)/Hudson Valley

Agloe is a fictional hamlet in Colchester, Delaware County, New York, that became an actual landmark after mapmakers made up the community as a phantom settlement, an example of a "copyright trap" and similar to a trap street. Agloe was put onto the map in order to catch plagiarism as it appears only on their map and not on any others. Soon, using fictional "copyright traps" became a typical strategy in mapmaker design to thwart plagiarism. Agloe was known as a "paper town" because of this.

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๐Ÿ”— Haversine Formula

๐Ÿ”— Mathematics ๐Ÿ”— Geography

The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. Important in navigation, it is a special case of a more general formula in spherical trigonometry, the law of haversines, that relates the sides and angles of spherical triangles.

The first table of haversines in English was published by James Andrew in 1805, but Florian Cajori credits an earlier use by Josรฉ de Mendoza y Rรญos in 1801. The term haversine was coined in 1835 by James Inman.

These names follow from the fact that they are customarily written in terms of the haversine function, given by hav(ฮธ) = sin2(ฮธ/2). The formulas could equally be written in terms of any multiple of the haversine, such as the older versine function (twice the haversine). Prior to the advent of computers, the elimination of division and multiplication by factors of two proved convenient enough that tables of haversine values and logarithms were included in nineteenth and early twentieth century navigation and trigonometric texts. These days, the haversine form is also convenient in that it has no coefficient in front of the sin2 function.

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๐Ÿ”— Aosta Valley Autonomus Region

๐Ÿ”— Italy ๐Ÿ”— Geography

The Aosta Valley (Italian: Valle d'Aosta [หˆvalle daหˆษ”sta] (official) or Val d'Aosta (usual); French: Vallรฉe d'Aoste; Arpitan: Val d'Outa; Walser: Augschtalann or Ougstalland; Piedmontese: Val d'Osta) is a mountainous autonomous region in northwestern Italy. It is bordered by Auvergne-Rhรดne-Alpes, France, to the west, Valais, Switzerland, to the north, and by Piedmont, Italy, to the south and east. The regional capital is Aosta.

Covering an area of 3,263ย km2 (1,260ย sqย mi) and with a population of about 128,000 it is the smallest, least populous, and least densely populated region of Italy. The province of Aosta having been dissolved in 1945, the Aosta Valley region was the first region of Italy to abolish provincial subdivisions. Provincial administrative functions are provided by the regional government. The region is divided into 74 comuni (French: communes).

Italian and French are the official languages, though the native population also speak Valdรดtain, a dialect of Franco-Provenรงal. Italian is spoken as a mother tongue by 77.29% of population, Valdรดtain by 17.91%, and French by 1.25%. In 2009, reportedly 50.53% of the population could speak all three languages.

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๐Ÿ”— Blue iceberg

๐Ÿ”— Geography ๐Ÿ”— Antarctica ๐Ÿ”— Glaciers

A blue iceberg is visible after the ice from above the water melts, causing the smooth portion of ice from below the water to overturn. The rare blue ice is formed from the compression of pure snow, which then develops into glacial ice.

Icebergs may also appear blue due to light refraction and age. Older icebergs reveal vivid hues of green and blue, resulting from a high concentration of color, microorganisms, and compacted ice. One of the better known blue icebergs rests in the waters off Sermilik fjord near Greenland. It is described as an electric blue iceberg and is known to locals as "blue diamond".

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๐Ÿ”— Tobler's First Law of Geography

๐Ÿ”— Geography

The First Law of Geography, according to Waldo Tobler, is "everything is related to everything else, but near things are more related than distant things." This first law is the foundation of the fundamental concepts of spatial dependence and spatial autocorrelation and is utilized specifically for the inverse distance weighting method for spatial interpolation and to support the regionalized variable theory for kriging. It is a modern formulation of David Hume's principle of contiguity.

Tobler first presented his seminal idea during a meeting of the International Geographical Union's Commission on Qualitative Methods held in 1969 and later published by him in 1970. Though simple in its presentation, this idea is profound. Without it, "the full range of conditions anywhere on the Earth's surface could in principle be found packed within any small area. There would be no regions of approximately homogeneous conditions to be described by giving attributes to area objects. Topographic surfaces would vary chaotically, with slopes that were everywhere infinite, and the contours of such surfaces would be infinitely dense and contorted. Spatial analysis, and indeed life itself, would be impossible."

Less well known is his second law, which complements the first: "The phenomenon external to an area of interest affects what goes on inside".

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