1.
Salt Lake City
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Salt Lake City, often shortened to Salt Lake or SLC, is the capital and the most populous municipality of the U. S. state of Utah. With an estimated population of 190,884 in 2014, the city lies at the core of the Salt Lake City metropolitan area, Salt Lake City is further situated within a larger metropolis known as the Salt Lake City-Ogden-Provo Combined Statistical Area. This region is a corridor of contiguous urban and suburban development stretched along an approximately 120-mile segment of the Wasatch Front and it is one of only two major urban areas in the Great Basin. The city was founded in 1847 by Brigham Young, Isaac Morley, George Washington Bradley and numerous other Mormon followers, who extensively irrigated and cultivated the arid valley. Due to its proximity to the Great Salt Lake, the city was originally named Great Salt Lake City—the word great was dropped from the name in 1868 by the 17th Utah Territorial Legislature. Today, however, less than half the population of Salt Lake City proper are members of the LDS Church. It was traversed by the Lincoln Highway, the first transcontinental highway, in 1913, Salt Lake City has since developed a strong outdoor recreation tourist industry based primarily on skiing, and hosted the 2002 Winter Olympics. It is the banking center of the United States. Before Mormon settlement, the Shoshone, Ute, and Paiute had dwelt in the Salt Lake Valley for thousands of years. The land was treated by the United States as public domain, the first U. S. explorer in the Salt Lake area is believed to be Jim Bridger in 1825, although others had been in Utah earlier, some as far north as the nearby Utah Valley. Frémont surveyed the Great Salt Lake and the Salt Lake Valley in 1843 and 1845, the Donner Party, a group of ill-fated pioneers, had traveled through the Great Salt Lake Valley in August 1846. The first permanent settlements in the date to the arrival of the Latter-day Saints on July 24,1847. Upon arrival at the Salt Lake Valley, president of the church Brigham Young is recorded as stating, This is the right place, Brigham Young claimed to have seen the area in a vision prior to the wagon trains arrival. They found the broad valley empty of any human settlement, four days after arriving in the Salt Lake Valley, Brigham Young designated the building site for the Salt Lake Temple, which would eventually become a famous Mormon and Salt Lake City landmark. The Salt Lake Temple, constructed on the block that would later be called Temple Square, construction started in 1853, and the temple was dedicated on 6 April 1893. The temple has become an icon for the city and serves as its centerpiece, in fact, the southeast corner of Temple Square is the initial point of reference for the Salt Lake Meridian, and for all addresses in the Salt Lake Valley. The Mormon pioneers organized a new state called Deseret and petitioned for its recognition in 1849, the United States Congress rebuffed the settlers in 1850 and established the Utah Territory, vastly reducing its size, and designated Fillmore as its capital city. Great Salt Lake City replaced Fillmore as the capital in 1858
2.
University of Utah
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The University of Utah is a public coeducational space-grant research university in Salt Lake City, Utah, United States. As the states flagship university, the university more than 100 undergraduate majors. The university is classified in the highest ranking, R-1, Doctoral Universities – Highest Research Activity by the Carnegie Classification of Institutions of Higher Education, the Carnegie Classification also considers the university as selective, which is its second most selective admissions category. Quinney College of Law and the School of Medicine, Utahs only medical school, as of Fall 2015, there are 23,909 undergraduate students and 7,764 graduate students, for an enrollment total of 31,673. The university was established in 1850 as the University of Deseret by the General Assembly of the provisional State of Deseret and it received its current name in 1892, four years before Utah attained statehood, and moved to its current location in 1900. The university ranks among the top 50 U. S. universities by total research expenditures with over $486 million spent in 2014, in addition, the universitys Honors College has been reviewed among 50 leading national Honors Colleges in the U. S. The university has also ranked the 12th most ideologically diverse university in the country. The universitys athletic teams, the Utes, participate in NCAA Division I athletics as a member of the Pac-12 Conference and its football team has received national attention for winning the 2005 Fiesta Bowl and the 2009 Sugar Bowl. A Board of Regents was organized by Brigham Young to establish a university in the Salt Lake Valley, early classes were held in private homes or wherever space could be found. The university closed in 1853 due to lack of funds and lack of feeder schools, the university moved out of the council house into the Union Academy building in 1876 and into Union Square in 1884. Additional Fort Douglas land has granted to the university over the years. Upon his death in 1900, Dr. John R. Park bequeathed his fortune to the university. One third of the faculty resigned in protest of these dismissals, the controversy was largely resolved when Kingsbury resigned in 1916, but university operations were again interrupted by World War I, and later The Great Depression and World War II. Student enrollment dropped to a low of 3,418 during the last year of World War II, ray Olpin made substantial additions to campus following the war, and enrollment reached 12,000 by the time he retired in 1964. Growth continued in the decades as the university developed into a research center for fields such as computer science. During the 2002 Winter Olympics, the university hosted the Olympic Village, the University of Utah Asia Campus opened as an international branch campus in the Incheon Global Campus in Songdo, Incheon, South Korea in 2014. Three other European and American universities are also participating, the Asia Campus was funded by the South Korean government. Campus takes up 1,534 acres, including the Health Sciences complex, Research Park and it is located on the east bench of the Salt Lake Valley, close to the Wasatch Range and approximately 2 miles east of downtown Salt Lake City
3.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
4.
Western United States
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The Western United States, commonly referred to as the American West, the Far West, or simply the West, traditionally refers to the region comprising the westernmost states of the United States. Because European settlement in the U. S. expanded westward after its founding, prior to about 1800, the crest of the Appalachian Mountains was seen as the western frontier. Since then, the frontier moved westward and eventually lands west of the Mississippi River came to be referred to as the West. The West contains several major biomes, the Western U. S. is the largest region of the country, covering more than half the land area of the United States. Given this expansive and diverse geography it is no wonder the region is difficult to specifically define, a majority of the historian respondents placed the eastern boundary of the West east of the Census definition out on the eastern edge of the Great Plains or on the Mississippi River. The survey respondents as a whole showed just how little agreement there was on the boundaries of the West, within a region as large and diverse as the Western United States, smaller areas with more closely shared demographics and geography have developed as subregions. Meanwhile, the states of Idaho, Montana, Oregon and Washington can be considered part of the Northwest or Pacific Northwest, West Texas in the Chihuahuan Desert may be considered as part of the Western U. S. Fort Worth has long laid claim to be Where the West Begins, the West is still one of the most sparsely settled areas in the United States with 49.5 inhabitants per square mile. Only Texas with 78.0 inhabitants/sq mi, Washington with 86.0 inhabitants/sq mi. and California with 213.4 inhabitants/sq mi. exceed the national average of 77.98 inhabitants/sq mi. The entire Western region has also strongly influenced by European, Hispanic or Latino, Asian and Native Americans. African and European Americans, however, continue to wield a stronger political influence because of the rates of citizenship and voting among Asians. The West also contains much of the Native American population in the U. S. particularly in the reservations in the Mountain. The Western United States has a sex ratio than any other region in the United States. Because the tide of development had not yet reached most of the West when conservation became an issue, agencies of the federal government own. National parks are reserved for activities such as fishing, camping, hiking, and boating, but other government lands also allow commercial activities like ranching, logging. The largest city in the region is Los Angeles, located on the West Coast, Other West Coast cities include San Diego, San Bernardino, San Jose, San Francisco, Oakland, Bakersfield, Sacramento, Seattle, Tacoma, and Portland. Prominent cities in the Mountain States include Denver, Colorado Springs, Phoenix, Tucson, Albuquerque, Las Vegas, Salt Lake City, Boise, El Paso, and Cheyenne. Along the Pacific Ocean coast lie the Coast Ranges, which and they collect a large part of the airborne moisture moving in from the ocean
5.
Chemical substance
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A chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical methods, i. e. without breaking chemical bonds. Chemical substances can be chemical elements, chemical compounds, ions or alloys, Chemical substances are often called pure to set them apart from mixtures. A common example of a substance is pure water, it has the same properties. Other chemical substances commonly encountered in pure form are diamond, gold, table salt, however, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical. Chemical substances exist as solids, liquids, gases, or plasma, Chemical substances may be combined or converted to others by means of chemical reactions. Forms of energy, such as light and heat, are not matter, a chemical substance may well be defined as any material with a definite chemical composition in an introductory general chemistry textbook. According to this definition a chemical substance can either be a chemical element or a pure chemical compound. But, there are exceptions to this definition, a substance can also be defined as a form of matter that has both definite composition and distinct properties. The chemical substance index published by CAS also includes several alloys of uncertain composition, in geology, substances of uniform composition are called minerals, while physical mixtures of several minerals are defined as rocks. Many minerals, however, mutually dissolve into solid solutions, such that a rock is a uniform substance despite being a mixture in stoichiometric terms. Feldspars are an example, anorthoclase is an alkali aluminium silicate. In law, chemical substances may include both pure substances and mixtures with a composition or manufacturing process. For example, the EU regulation REACH defines monoconstituent substances, multiconstituent substances and substances of unknown or variable composition, the latter two consist of multiple chemical substances, however, their identity can be established either by direct chemical analysis or reference to a single manufacturing process. For example, charcoal is a complex, partially polymeric mixture that can be defined by its manufacturing process. Therefore, although the chemical identity is unknown, identification can be made to a sufficient accuracy. The CAS index also includes mixtures, polymers almost always appear as mixtures of molecules of multiple molar masses, each of which could be considered a separate chemical substance. However, the polymer may be defined by a precursor or reaction
6.
Jon Huntsman Jr.
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He has served in the administrations of five U. S. Presidents and was a candidate for the 2012 Republican presidential nomination. In January 2014, Huntsman was named Chairman of the Washington-based foreign policy think-tank the Atlantic Council and it has been reported he was chosen to be the next Ambassador to Russia in March 2017. Huntsman has served in every administration since Ronald Reagan. He began his career as a White House staff assistant for Ronald Reagan, later as Deputy U. S. Trade Representative under George W. Bush, he launched global trade negotiations in Doha in 2001 and guided the accession of China into the World Trade Organization. He also served as CEO of his family-owned Huntsman Corporation and chairman of the Huntsman Cancer Foundation, in 2009, he was appointed United States Ambassador to China by Barack Obama. While Governor, he was named Chairman of the Western Governors Association, under his leadership, Utah was named the best managed state in America by the Pew Center on the States. He won re-election in 2008 with nearly 78% of the vote, Huntsman was born March 26,1960 in Redwood City, California. His mother is Karen Huntsman, daughter of LDS Church apostle David B, haight, and his father is billionaire businessman and philanthropist Jon Huntsman Sr. of the Huntsman Corporation. Through his father, Huntsman Jr. is the great-great-great-grandson of early LDS Church leader Parley P. Pratt, at age 15 in 1975, Huntsman earned the rank of Eagle Scout, the highest rank of the Boy Scouts of America. Huntsman attended Highland High School in Salt Lake City, but dropped out before graduating to pursue his passion as a player in a rock band called Wizard. Huntsman later obtained a G. E. D. and enrolled at the University of Utah, where he became, like his father, a member of the Sigma Chi fraternity. Huntsman served as a Mormon missionary in Taiwan for two years and later transferred to the University of Pennsylvania, where he received a Bachelor of Arts in international politics in 1987. While visiting the White House in 1971 during his fathers service as Special Assistant to the President and he worked as a White House staff assistant in President Ronald Reagans administration in 1983. From 1987 to 1988, Huntsman and his family lived and worked in Taipei, in the 1988 presidential election, he was a state delegate at the 1988 Republican National Convention. Under President George H. W. Bush, Huntsman was deputy assistant secretary in the International Trade Administration from 1989 to 1990 and he subsequently served as Deputy Assistant Secretary of Commerce for trade development and commerce for East Asian and Pacific Affairs, serving from 1990 to 1991. In June 1992, Bush appointed Huntsman to become U. S. Ambassador to Singapore and he became the youngest U. S. Ambassador to serve in over 100 years. In January 2001, after George W. Bush took office as President, in March, he reportedly turned down the nomination to be the U. S. Ambassador to Indonesia. On March 28, Bush appointed Huntsman to be one of two Deputy United States Trade Representatives in his administration, he served in this role from 2001 to 2003, in March 2003, Huntsman resigned his post in the Bush administration
7.
Vivint Smart Home Arena
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Vivint Smart Home Arena is an indoor arena located in Salt Lake City, Utah. The building is owned by Jazz Basketball Investors, Inc. the estate of Larry H. Miller and it seats 19,911 for basketball, has 56 luxury suites, and 668 club seats. Opened in 1991, the arena was known as the Delta Center, under a naming deal with Delta Air Lines which has a hub at Salt Lake City International Airport. Salt Lake City-based EnergySolutions purchased the rights in November 2006. From 2006 to 2015 it was known as EnergySolutions Arena, on October 26,2015, the arena was renamed as part of a 10-year naming rights contract with the Provo, Utah-based home security system provider Vivint. On September 21,2016, the Utah Jazz announced plans to renovate, the arena was also home to the figure skating and short track speed skating competitions of the 2002 Winter Olympics, where it was referred to as the Salt Lake Ice Center. The arena was originally imagined as 20, 000-seat home for the Utah Jazz and Salt Lake Golden Eagles to replace the arena of the Salt Palace. Under the leadership and private financing of Utah businessman Larry H, the Eagles had also played the inaugural game in the Salt Palace arena when it opened on October 10,1969. The Eagles, which were purchased by Miller in 1990, lost nearly a million dollars annually, the first basketball game played in the arena was a Jazz pre-season loss against Patrick Ewing and the New York Knicks, 101–95. In addition to sports, the arena was intended to host large music concerts, on October 24,1991, Oingo Boingo became the first headlining act to rock the Delta Center. The 1993–95 Western Athletic Conference mens basketball tournaments were held at the facility, the Delta Center also hosted games of the 1997 and 1998 NBA Finals between the Jazz and Chicago Bulls. The arenas roof was damaged by severe winds associated with the Salt Lake City Tornado of August 11,1999, the facility played host to the 1999 US Figure Skating Championships. The arena was home to the figure skating and short track speed skating competitions of the 2002 Winter Olympics. Notably, on June 8,1996, the Delta Center hosted what was then the largest crowd in the history of American minor league hockey,17,381 fans attended Game 4 of the 1996 Turner Cup Finals. The Grizzlies won 3–2 in overtime, completing a sweep of the Orlando Solar Bears. In 2002, the arena upgraded its system with ribbon display technology and auxiliary scoreboards from Brookings. The movie Legally Blonde 2 was partially filmed in the arena, dan Roberts serves as the official Vivint Smart Home Arena public address voice for the Jazz. He has been the Jazzs home game announcer since before the arena was built, Vivint Smart Home Arena is well known for being one of the hardest places to play for visiting teams in the NBA
8.
Elevation
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GIS or geographic information system is a computer system that allows for visualizing, manipulating, capturing, and storage of data with associated attributes. GIS offers better understanding of patterns and relationships of the landscape at different scales, tools inside the GIS allow for manipulation of data for spatial analysis or cartography. A topographical map is the type of map used to depict elevation. In a Geographic Information System, digital models are commonly used to represent the surface of a place. Digital terrain models are another way to represent terrain in GIS, USGS is developing a 3D Elevation Program to keep up with growing needs for high quality topographic data. 3DEP is a collection of enhanced elevation data in the form of high quality LiDAR data over the conterminous United States, Hawaii, there are three bare earth DEM layers in 3DEP which are nationally seamless at the resolution of 1/3,1, and 2 arcseconds. This map is derived from GTOPO30 data that describes the elevation of Earths terrain at intervals of 30 arcseconds and it uses color and shading instead of contour lines to indicate elevation. Hypsography is the study of the distribution of elevations on the surface of the Earth, the term originates from the Greek word ὕψος hypsos meaning height. Most often it is used only in reference to elevation of land, related to the term hypsometry, the measurement of these elevations of a planets solid surface are taken relative to mean datum, except for Earth which is taken relative to the sea level. In the troposphere, temperatures decrease with altitude and this lapse rate is approximately 6.5 °C/km. S
9.
NCAA Division I Men's Basketball Tournament
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The tournament was created in 1939 by the National Association of Basketball Coaches, and was the idea of Ohio State University coach Harold Olsen. Played mostly during March, it has one of the most famous annual sporting events in the United States. The tournament teams include champions from 32 Division I conferences, and 36 teams which are awarded at-large berths, the 68 teams are divided into four regions and organized into a single-elimination bracket, which pre-determines, when a team wins a game, which team it will face next. Each team is seeded, or ranked, within its region from 1 to 32, after an initial four games between eight lower-ranked teams, the tournament occurs during the course of three weekends, at pre-selected neutral sites across the United States. The Final Four is usually played during the first weekend of April and these four teams, one from each region, compete in a pre-selected location for the national championship. The tournament has been at least partially televised since 1969, currently, the games are broadcast by CBS, TBS, TNT, and truTV under the trade-name NCAA March Madness. Since 2011, all games are available for viewing nationwide and internationally, such as in the Philippines, as television coverage has grown, so too has the tournaments popularity. Currently, millions of Americans fill out a bracket, attempting to predict the outcome of all 67 games of the tournament. With 11 national titles, UCLA has the record for the most NCAA Mens Division I Basketball Championships, the University of Kentucky is second, with eight national titles. The University of North Carolina is in place, with six titles, while Duke University. The University of Connecticut is sixth with four national titles, the University of Kansas and University of Louisville are tied with three championships. During that time Villanova, Michigan, UNLV, Duke, Arkansas, Arizona, Connecticut, Maryland, Syracuse, the NCAA has changed the tournament format several times since its inception, most often representing an increase of the number of teams. This section describes the tournament as it has operated since 2011, for changes during the course of its history, and to see how the tournament operated during past years, go to Format history, below. A total of 68 teams qualify for the tournament played during March, thirty-two teams earn automatic bids as their respective conference champions. Of the 32 Division I all-sports conferences, all 32 currently hold championship tournaments to determine which team receives the automatic qualification. The Ivy League was the last Division I conference that did not conduct a tournament, through the 2015–16 season, if two or more Ivies shared a regular-season championship, a one-game playoff was used to decide the tournament participant. Since 2017, the league conducts their own postseason tournament, the committee also determines where all sixty-eight teams are seeded and placed in the bracket. The tournament is divided into four regions and each region has at least sixteen teams, the committee is charged with making each of the four regions as close as possible in overall quality of teams from wherever they come from
10.
Pac-12 Conference
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The Pac-12 Conference is a collegiate athletic conference that operates in the Western United States. It participates in 22 NCAA sports in the NCAAs Division I, its teams compete in the Football Bowl Subdivision. The conferences 12 members are located in Arizona, California, Colorado, Oregon, Utah and they include each states flagship public university, four additional public universities, and two private research universities. It became the Pac-12 in 2011 with the addition of the University of Colorado, with Arizona States softball title in 2011, the conference won its 400th NCAA Championship. The current commissioner of the conference is Larry Scott, Scott replaced Thomas C, hansen, who retired in July 2009 after 26 years in that position. Prior to joining the Pac-10, Scott was Chairman and CEO of the Womens Tennis Association, the Pac-12 has twelve full member institutions. Football currently is the sport where the conference is divided evenly into two geographic divisions, the North Division and the South Division. The Pac-12 spans six states in the Western United States, Arizona, California, Colorado, Oregon, Utah, and Washington. Unusual for a conference, the Pac-12s members are spread evenly between 3 regions, with 4 schools each in California, the Pacific Northwest, and the Four Corners region. The Pac-12 has four affiliate member institutions, three in California and Boise State University in Idaho, the school will maintain its Pac-12 affiliation in wrestling, which the WAC does not sponsor. No school has left the Pac-12 since its founding as the AAWU in 1959, two members of the PCC were not invited to join the AAWU or its successors. As private schools, Stanford and USC are not obligated to publish employees salaries, Eight of the twelve member schools are members of the Association of American Universities, including all of the conferences California schools. The only FBS conference with more AAU members is the Big Ten with 13 out of 14 member institutions having AAU membership, in 2014, of the twelve member schools, nine were ranked in the top 100 universities in the world. Total revenue includes ticket sales, contributions and donations, rights/licensing, student fees, school funds and all sources including TV income, camp income, food. Updated to show institutional reporting to the Department of Education as shown on the DOE Equity in Athletics website for the 2013-14 academic year, the national ranking of revenue is based on 2075 institutions reporting to the Department of Education that year. The roots of the Pac-12 Conference go back to December 2,1915, charter members were the University of California, the University of Washington, the University of Oregon, and Oregon Agricultural College. The conference began play in 1916, one year later, Washington State College joined the league, followed by Stanford University in 1918. In 1922, the PCC expanded to eight teams with the admission of USC, Montana joined the Conference in 1924, and in 1928, the PCC grew to 10 members with the addition of UCLA
11.
Utah Jazz
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The Utah Jazz are an American professional basketball team based in Salt Lake City, Utah. The Jazz compete in the National Basketball Association as a club of the leagues Western Conference Northwest Division. Since 1991, the team has played its games at Vivint Smart Home Arena. The franchise began play in 1974 as the New Orleans Jazz, a team based in New Orleans. The Jazz were one of the least successful teams in the league in their early years, although 10 seasons elapsed before the Jazz qualified for their first playoff appearance in 1984, they did not miss the playoffs again until 2004. During the late 1980s, John Stockton and Karl Malone arose as the players for the team. Both Stockton and Malone moved on in 2003, after missing the playoffs for three consecutive seasons the Jazz returned to prominence under the on-court leadership of point guard Deron Williams. However, partway through the 2010–11 NBA season, the Jazz began restructuring after Sloans retirement, the team has made the playoffs once since then, in 2012 under coach Tyrone Corbin. Quin Snyder was hired as coach in June 2014. Valued in 2015 at $850 million by Forbes, the Jazz rank as the 20th most valuable franchise in the NBA ahead of the Indiana Pacers, on June 7,1974, the New Orleans Jazz were admitted as an expansion franchise into the National Basketball Association. Team officials selected the name because of its definition in the dictionary, the team began its inaugural season in New Orleans in the 1974–75 season. Maravich struggled with injuries from that season onward. Venue issues were a problem for the team while it was based in New Orleans. Later, they played games in the cavernous Louisiana Superdome, but things were no better, due to demand for the stadium, onerous lease terms. Years later, founding owner Sam Battistone claimed that there was no plan in case the Jazz ever qualified for the playoffs. The pick would have been the Jazzs had they not traded it to acquire Gail Goodrich two years earlier, despite being barely competitive, the Jazz drew well during their first five years. However, by 1979 the franchise was sinking financially, barry Mendelson, the teams executive vice president for most of the early years, said one factor in the financial trouble was an 11 percent amusement tax, highest in the U. S. at the time. The team also could not attract much local corporate support—an important factor even in those days—or local investors, Battistone concluded that the franchise could not be viable in New Orleans and decided to move elsewhere
12.
Sea level
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Mean sea level is an average level of the surface of one or more of Earths oceans from which heights such as elevations may be measured. A common and relatively straightforward mean sea-level standard is the midpoint between a low and mean high tide at a particular location. Sea levels can be affected by factors and are known to have varied greatly over geological time scales. The careful measurement of variations in MSL can offer insights into ongoing climate change, the term above sea level generally refers to above mean sea level. Precise determination of a sea level is a difficult problem because of the many factors that affect sea level. Sea level varies quite a lot on several scales of time and this is because the sea is in constant motion, affected by the tides, wind, atmospheric pressure, local gravitational differences, temperature, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point, for example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. One measures the values of MSL in respect to the land, hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates. In the UK, the Ordnance Datum is the sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the datum was MSL at the Victoria Dock, in Hong Kong, mPD is a surveying term meaning metres above Principal Datum and refers to height of 1. 230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and it is used for a part of continental Europe and main part of Africa as official sea level. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001, height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum. It is also used in aviation, where some heights are recorded and reported with respect to sea level, and in the atmospheric sciences. An alternative is to base height measurements on an ellipsoid of the entire Earth, in aviation, the ellipsoid known as World Geodetic System 84 is increasingly used to define heights, however, differences up to 100 metres exist between this ellipsoid height and mean tidal height. The alternative is to use a vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, the elevation of a mountain denotes the highest point or summit and is typically illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, for one such case, see Amsterdam Airport Schiphol
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