1.
Atlantic Ocean
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The Atlantic Ocean is the second largest of the worlds oceans with a total area of about 106,460,000 square kilometres. It covers approximately 20 percent of the Earths surface and about 29 percent of its surface area. It separates the Old World from the New World, the Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. The Equatorial Counter Current subdivides it into the North Atlantic Ocean, in contrast, the term Atlantic originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast. The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of years ago. The term Aethiopian Ocean, derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century, many Irish or British people refer to the United States and Canada as across the pond, and vice versa. The Black Atlantic refers to the role of ocean in shaping black peoples history. Irish migration to the US is meant when the term The Green Atlantic is used, the term Red Atlantic has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. Correspondingly, the extent and number of oceans and seas varies, the Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, to the east, the boundaries of the ocean proper are Europe, the Strait of Gibraltar and Africa. In the southeast, the Atlantic merges into the Indian Ocean, the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. In the 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean, the Atlantic has irregular coasts indented by numerous bays, gulfs, and seas. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23. 5% of the ocean and has a volume of 310,410,900 km3 or 23. 3%. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3, the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S, the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2000 m along most of its length, the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other
2.
Ice rafting
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Ice rafting is the transport of various materials by ice. Various objects deposited on ice may eventually become embedded in the ice, when the ice melts after a certain amount of drifting, these objects are deposited onto the bottom of the water body, e. g. onto a river bed or an ocean floor. These deposits are called ice rafted debris or ice rafted deposits, ice rafting was a primary mechanism of sediment transport during glacial episodes of the Pleistocene when sea levels were very low and much of the land was covered by large masses of ice. The rafting of various size sediments into deeper waters by icebergs became a rather important process. Ice rafting is still a process occurring today although its impact is significantly less, the melting of large icebergs deposits sediment of various sizes, usually referred to as glacial marine sediment, onto the shelf and deeper marine areas. Ice rafting may be used for analysis of ice drift pattern by matching the rafted sediment with its origin, ice rafting must also be taken into an account in archaeology and as a possible cause of displacement of archaeological artifacts
3.
Holocene
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The Holocene is the geological epoch that began after the Pleistocene at approximately 11,700 years before present. The term Recent has often used as an exact synonym of Holocene. The Holocene is part of the Quaternary period and its name comes from the Ancient Greek words ὅλος and καινός, meaning entirely recent. It has been identified with the current warm period, known as MIS1, given these, a new term, Anthropocene, is specifically proposed and used informally only for the very latest part of modern history involving significant human impact. It is accepted by the International Commission on Stratigraphy that the Holocene started approximately 11,700 years ago, the epoch follows the Pleistocene and the last glacial period. The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations, Preboreal, Boreal, Atlantic, Subboreal and they find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for Northern Europe, but the changes were claimed to occur more widely. The periods of the include a few of the final pre-Holocene oscillations of the last glacial period. Paleontologists have not defined any faunal stages for the Holocene, if subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world, climatically, the Holocene may be divided evenly into the Hypsithermal and Neoglacial periods, the boundary coincides with the start of the Bronze Age in Europe. According to some scholars, a division, the Anthropocene, has now begun. Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years, however, ice melt caused world sea levels to rise about 35 m in the early part of the Holocene. The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea, Holocene marine fossils are known, for example, from Vermont and Michigan. Other than higher-latitude temporary marine incursions associated with depression, Holocene fossils are found primarily in lakebed, floodplain. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely tectonic uplift of non-glacial origin, post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea. The region continues to rise, still causing weak earthquakes across Northern Europe, the equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to near its present boundaries. Climate has been stable over the Holocene. It appears that this was influenced by the glacial ice remaining in the Northern Hemisphere until the later date
4.
Columbia University
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Columbia University is a private Ivy League research university in Upper Manhattan, New York City. It was established in 1754 as Kings College by royal charter of George II of Great Britain, after the American Revolutionary War, Kings College briefly became a state entity, and was renamed Columbia College in 1784. Columbia is one of the fourteen founding members of the Association of American Universities and was the first school in the United States to grant the M. D. degree. The university also has global research outposts in Amman, Beijing, Istanbul, Paris, Mumbai, Rio de Janeiro, Santiago, Asunción, Columbia administers annually the Pulitzer Prize. Additionally,100 Nobel laureates have been affiliated with Columbia as students, researchers, faculty, Columbia is second only to Harvard University in the number of Nobel Prize-winning affiliates, with over 100 recipients of the award as of 2016. In 1746 an act was passed by the assembly of New York to raise funds for the foundation of a new college. Classes were initially held in July 1754 and were presided over by the colleges first president, Dr. Johnson was the only instructor of the colleges first class, which consisted of a mere eight students. Instruction was held in a new schoolhouse adjoining Trinity Church, located on what is now lower Broadway in Manhattan, in 1763, Dr. Johnson was succeeded in the presidency by Myles Cooper, a graduate of The Queens College, Oxford, and an ardent Tory. In the charged political climate of the American Revolution, his opponent in discussions at the college was an undergraduate of the class of 1777. The suspension continued through the occupation of New York City by British troops until their departure in 1783. The colleges library was looted and its sole building requisitioned for use as a hospital first by American. Loyalists were forced to abandon their Kings College in New York, the Loyalists, led by Bishop Charles Inglis fled to Windsor, Nova Scotia, where they founded Kings Collegiate School. After the Revolution, the college turned to the State of New York in order to restore its vitality, the Legislature agreed to assist the college, and on May 1,1784, it passed an Act for granting certain privileges to the College heretofore called Kings College. The Regents finally became aware of the colleges defective constitution in February 1787 and appointed a revision committee, in April of that same year, a new charter was adopted for the college, still in use today, granting power to a private board of 24 Trustees. On May 21,1787, William Samuel Johnson, the son of Dr. Samuel Johnson, was unanimously elected President of Columbia College, prior to serving at the university, Johnson had participated in the First Continental Congress and been chosen as a delegate to the Constitutional Convention. The colleges enrollment, structure, and academics stagnated for the majority of the 19th century, with many of the college presidents doing little to change the way that the college functioned. In 1857, the college moved from the Kings College campus at Park Place to a primarily Gothic Revival campus on 49th Street and Madison Avenue, during the last half of the 19th century, under the leadership of President F. A. P. Barnard, the institution assumed the shape of a modern university
5.
Petrologic
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Petrology is the branch of geology that studies the origin, composition, distribution and structure of rocks. In the petroleum industry, lithology, or more specifically mud logging, is the representation of geological formations being drilled through. As the cuttings are circulated out of the borehole they are sampled, examined and tested chemically when needed, Petrology utilizes the fields of mineralogy, petrography, optical mineralogy, and chemical analysis to describe the composition and texture of rocks. Igneous rocks include volcanic and plutonic rocks, sedimentary petrology focuses on the composition and texture of sedimentary rocks. Experiments are particularly useful for investigating rocks of the lower crust and they are also one of the prime sources of information about completely inaccessible rocks such as those in the Earths lower mantle and in the mantles of the other terrestrial planets and the Moon. The work of experimental petrologists has laid a foundation on which modern understanding of igneous, important publications in petrology Ore Soil Best, Myron G. Igneous and Metamorphic Petrology. ISBN 1-4051-0588-7 Blatt, Harvey, Tracy, Robert J. Owens, Brent, Petrology, igneous, sedimentary, ISBN 978-0-7167-3743-8 Dietrich, Richard Vincent, Skinner, Brian J. Gems, Granites, and Gravels, knowing and using rocks and minerals. ISBN 978-0-521-10722-8 Fei, Yingwei, Bertka, Constance M. Mysen, mantle Petrology, field observations and high-pressure experimentation. ISBN 0-941809-05-6 Philpotts, Anthony, Ague, Jay, Principles of Igneous and Metamorphic Petrology
6.
North Greenland Ice Core Project
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The drilling site of the North Greenland Ice Core Project is near the center of Greenland. Drilling began in 1999 and was completed at bedrock in 2003, the cores are cylinders of ice 11 centimeters in diameter that were brought to the surface in 3. 5-meter lengths. The NGRIP site was chosen to extract a long and undisturbed record stretching into the last glacial, the site was chosen for a flat basal topography to avoid the flow distortions that render the bottom of the GRIP and GISP cores unreliable. Unusually, there is melting at the bottom of the NGRIP core - believed to be due to a geothermal heat flux locally. The NGRIP record helps to resolve a problem with the GRIP, NGRIP covers 5 kyr of the Eemian, and shows that temperatures then were roughly as stable as the pre-industrial Holocene temperatures were. This is confirmed by sediment cores, in particular MD95-2042, in 2003, NGRIP recovered what seem to be plant remnants nearly two miles below the surface, and they may be several million years old. Several of the look very much like blades of grass or pine needles, said University of Colorado at Boulder geological sciences Professor James White. If confirmed, this will be the first organic material ever recovered from a deep ice-core drilling project, the original web page of the NGRIP project with field diaries and pictures. This research centre maintains a web page about ice core research, http, //www. iceandclimate. nbi. ku. dk/research/drill_analysing/history_drilling/search_eemian/
7.
Ice core
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An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the buildup of annual layers of snow, lower layers are older than upper. The properties of the ice and the recrystallized inclusions within the ice can then be used to reconstruct a record over the age range of the core. This enables the reconstruction of local records and the history of atmospheric composition. Ice cores contain an abundance of information about climate, inclusions in the snow of each year remain in the ice, such as wind-blown dust, ash, pollen, bubbles of atmospheric gas and radioactive substances. The variety of climatic proxies is greater than in any other natural recorder of climate, the length of the record depends on the depth of the ice core and varies from a few years up to 800 kyr for the EPICA core. The time resolution depends on the amount of snowfall. Upper layers of ice in a core correspond to a year or sometimes a single season. Deeper into the ice the layers thin and annual layers become indistinguishable and it is the simultaneity of these properties recorded in the ice that makes ice cores such a powerful tool in paleoclimate research. Ice sheets are formed from snow, because an ice sheet survives summer, the temperature in that location usually does not warm much above freezing. In many locations in Antarctica the air temperature is well below the freezing point of water. If the summer temperatures do get above freezing, any ice core record will be degraded or completely useless. The surface layer is snow in various forms, with air gaps between snowflakes, as snow continues to accumulate, the buried snow is compressed and forms firn, a grainy material with a texture similar to granulated sugar. Air gaps remain, and some circulation of air continues, as snow accumulates above, the firn continues to densify, and at some point the pores close off and the air is trapped. Because the air continues to circulate until then, the ice age and the age of the gas enclosed are not the same, the gas age–ice age difference is as great as 7 kyr in glacial ice from Vostok. Under increasing pressure, at depth the firn is compressed into ice. This depth may range between a few to tens of meters to typically 100 m for Antarctic cores. Below this level material is frozen in the ice, Ice may appear clear or blue
8.
Asia
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Asia covers an area of 44,579,000 square kilometres, about 30% of Earths total land area and 8. 7% of the Earths total surface area. The continent, which has long been home to the majority of the population, was the site of many of the first civilizations. Asia is notable for not only its large size and population. In general terms, Asia is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean, the western boundary with Europe is a historical and cultural construct, as there is no clear physical and geographical separation between them. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of the Caucasus Mountains, China and India alternated in being the largest economies in the world from 1 to 1800 A. D. The accidental discovery of America by Columbus in search for India demonstrates this deep fascination, the Silk Road became the main East-West trading route in the Asian hitherland while the Straits of Malacca stood as a major sea route. Asia has exhibited economic dynamism as well as robust population growth during the 20th century, given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may actually have more to do with human geography than physical geography. Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties, the boundary between Asia and Africa is the Red Sea, the Gulf of Suez, and the Suez Canal. This makes Egypt a transcontinental country, with the Sinai peninsula in Asia, the border between Asia and Europe was historically defined by European academics. In Sweden, five years after Peters death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia, the Russians were enthusiastic about the concept, which allowed them to keep their European identity in geography. Tatishchev announced that he had proposed the idea to von Strahlenberg, the latter had suggested the Emba River as the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century, the border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects. The border between the Black Sea and the Caspian is usually placed along the crest of the Caucasus Mountains, the border between Asia and the loosely defined region of Oceania is usually placed somewhere in the Malay Archipelago. The terms Southeast Asia and Oceania, devised in the 19th century, have had several different geographic meanings since their inception. The chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the possessions of the various empires there. Lewis and Wigen assert, The narrowing of Southeast Asia to its present boundaries was thus a gradual process, Asia is larger and more culturally diverse than Europe. It does not exactly correspond to the borders of its various types of constituents. From the time of Herodotus a minority of geographers have rejected the three-continent system on the grounds there is no or is no substantial physical separation between them
9.
Monsoon
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Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. The term is sometimes used for locally heavy but short-term rains. The major monsoon systems of the world consist of the West African and Asia-Australian monsoons, the inclusion of the North and South American monsoons with incomplete wind reversal has been debated. The south-west monsoon winds are called Nairutya Maarut in India, the English monsoon came from Portuguese monção, ultimately from Arabic mawsim and/or Hindi mausam, perhaps partly via early modern Dutch monsun. Strengthening of the Asian monsoon has been linked to the uplift of the Tibetan Plateau after the collision of the Indian sub-continent and Asia around 50 million years ago. Because of studies of records from the Arabian Sea and that of the wind-blown dust in the Loess Plateau of China, testing of this hypothesis awaits deep ocean sampling by the Integrated Ocean Drilling Program. The monsoon has varied significantly in strength since this time, largely linked to climate change. A study of marine plankton suggested that the Indian Monsoon strengthened around 5 million years ago, then, during ice periods, the sea level fell and the Indonesian Seaway closed. When this happened, cold waters in the Pacific were impeded from flowing into the Indian Ocean and it is believed that the resulting increase in sea surface temperatures in the Indian Ocean increased the intensity of monsoons. Five episodes during the Quaternary at 2.22 Ma,1.83 Ma,0.68 Ma,0.45 Ma and 0.04 Ma were identified which showed a weakening of Leeuwin Current. The weakening of the LC would have an effect on the sea surface temperature field in the Indian Ocean, thus these five intervals could probably be those of considerable lowering of SST in the Indian Ocean and would have influenced Indian monsoon intensity. The impact of monsoon on the weather is different from place to place. In some places there is just a likelihood of having a more or less rain. In other places, quasi semi-deserts are turned into green grasslands where all sorts of plants. The Indian Monsoon turns large parts of India from a kind of semi-desert into green lands, see photos only taken 3 months apart in the Western Ghats. In places like this it is crucial for farmers to have the right timing for putting the seeds on the fields, Monsoons are large-scale sea breezes which occur when the temperature on land is significantly warmer or cooler than the temperature of the ocean. These temperature imbalances happen because oceans and land absorb heat in different ways, in contrast, dirt, sand, and rocks have lower heat capacities, and they can only transmit heat into the earth by conduction and not by convection. Therefore, bodies of water stay at an even temperature
10.
Middle East
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The Middle East is a transcontinental region centered on Western Asia and Egypt. The corresponding adjective is Middle-Eastern and the noun is Middle-Easterner. The term has come into usage as a replacement of the term Near East beginning in the early 20th century. Arabs, Turks, Persians, Kurds, and Azeris constitute the largest ethnic groups in the region by population. Indigenous minorities of the Middle East include Jews, Assyrians and other Arameans, Baloch, Berbers, Copts, Druze, Lurs, Mandaeans, Samaritans, Shabaks, Tats, in the Middle East, there is also a Romani community. European ethnic groups form a diaspora in the region include Albanians, Bosniaks, Circassians, Crimean Tatars, Franco-Levantines. Among other migrant populations are Bengalis as well as other Indians, Chinese, Filipinos, Indonesians, Pakistanis, the history of the Middle East dates back to ancient times, with the importance of the region being recognized for millennia. Most of the countries border the Persian Gulf have vast reserves of crude oil. The term Middle East may have originated in the 1850s in the British India Office, however, it became more widely known when American naval strategist Alfred Thayer Mahan used the term in 1902 to designate the area between Arabia and India. During this time the British and Russian Empires were vying for influence in Central Asia, Mahan realized not only the strategic importance of the region, but also of its center, the Persian Gulf. Mahan first used the term in his article The Persian Gulf and International Relations, published in September 1902 in the National Review, a British journal. The Middle East, if I may adopt a term which I have not seen, will some day need its Malta, as well as its Gibraltar, it does not follow that either will be in the Persian Gulf. The British Navy should have the facility to concentrate in force if occasion arise, about Aden, India, mahans article was reprinted in The Times and followed in October by a 20-article series entitled The Middle Eastern Question, written by Sir Ignatius Valentine Chirol. During this series, Sir Ignatius expanded the definition of Middle East to include regions of Asia which extend to the borders of India or command the approaches to India. After the series ended in 1903, The Times removed quotation marks from subsequent uses of the term, in the late 1930s, the British established the Middle East Command, which was based in Cairo, for its military forces in the region. After that time, the term Middle East gained broader usage in Europe, the description Middle has also led to some confusion over changing definitions. Before the First World War, Near East was used in English to refer to the Balkans and the Ottoman Empire, while Middle East referred to Iran, the Caucasus, Afghanistan, Central Asia, and Turkestan. The first official use of the term Middle East by the United States government was in the 1957 Eisenhower Doctrine, the Associated Press Stylebook says that Near East formerly referred to the farther west countries while Middle East referred to the eastern ones, but that now they are synonymous
11.
Heinrich event
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A Heinrich event is a natural phenomenon in which large armadas of icebergs break off from glaciers and traverse the North Atlantic. First described by marine geologist Hartmut Heinrich, they occurred during five of the last seven glacial periods or ice ages over the past 640,000 years, Heinrich events are particularly well documented for the last glacial period but notably absent from the penultimate glaciation. The icebergs contained rock mass, which has been eroded by the glaciers, and as they melted, the icebergs melting caused extensive amounts of fresh water to be added to the North Atlantic. Such inputs of cold and fresh water may well have altered the density-driven, thermohaline circulation patterns of the ocean, other northern hemisphere ice sheets were potentially involved as well. However, the cause of this instability is still debated. By extension, the name Heinrich events can also refer to the associated climatic anomalies registered at other places around the globe, at approximately the same time periods. The events are rapid, they last probably less than a millennium, a duration varying from one event to the next, some identify the Younger Dryas event as a Heinrich event, which would make it event H0. However, difficulties in synchronising marine sediment cores and Greenland ice cores to the time scale cast aspersions on the accuracy of that statement. Heinrichs original observations were of six layers in ocean sediment cores with extremely high proportions of rocks of continental origin, lithic fragments, the signature of the events in sediment cores varies considerably with distance from the source region. During Heinrich events, huge volumes of water flow into the ocean. H3 and H6 do not share such a suite of Heinrich event symptoms as events H1, H2, H4, and H5. Bonds suggestion of Heinrich events fitting into a 7, 000-year cycle suspect, several lines of evidence suggest that H3 and H6 were somehow different from the other events. Lithic peaks, a far smaller proportion of lithics is observed in H3 and H6, foram dissolution, Foraminifera tests appear to be more eroded during H3 and H6. That may indicate an influx of nutrient-rich, hence corrosive, Antarctic Bottom Water by a reconfiguration of oceanic circulation patterns, ice rafted debris distribution, Sediment transported by ice does not extend as far East during H3/6. As with so many climate related issues, the system is far too complex to be assigned to a single cause. There are several drivers, which fall into two categories. This model suggests that factors internal to ice sheets cause the disintegration of major ice volumes. The gradual accumulation of ice on the Laurentide ice sheet led to a increase in its mass
12.
8.2 kiloyear event
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During the event, atmospheric methane concentration decreased by 80 ppb or an emission reduction of 15%, by cooling and drying at a hemispheric scale. A rapid cooling around 6200 BCE was first identified by Swiss botanist Heinrich Zoller in 1960 and it is also known as Finse event in Norway. Bond et al. argued that the origin of the 8.2 kiloyear event is linked to a 1, 500-year climate cycle and it is less evident in ice cores from Antarctica and in South American indices. The effects of the cold snap were global, however, most notably in changes in sea level during the relevant era, the same type of action produced the Missoula floods that created the Channeled scablands of the Columbia River basin. The melt-water pulse may have affected the North Atlantic thermohaline circulation, reducing northward heat transport in the Atlantic, estimates of the cooling vary and depend somewhat on the interpretation of the proxy data, but drops of around 1 to 5 °C have been reported. In Greenland, the event started at 8175 BP, and the cooling was 3.3 °C in less than 20 years, the coldest period lasted for about 60 years, while the total duration was about 150 years. The melt-water causation theory is, however, thrown in to speculation due to inconstancies with its onset, researchers suggest the discharge was probably superimposed upon a longer episode of cooler climate lasting up to 600 years, and merely one contributing factor to the event as a whole. Further afield, some records report a 3 °C cooling from cores drilled into an ancient coral reef in Indonesia. The event also caused a global CO2 decline of ≈25 ppm over ≈300 years, however, dating and interpretation other tropical sites are more ambiguous than the North Atlantic sites. In addition, climate modeling work shows that not only the amount of meltwater, drier conditions were notable in North Africa while East Africa suffered five centuries of general drought. In West Asia and especially Mesopotamia, the 8, however, multi-centennial changes around the same period are difficult to link specifically to the approximately 100-year abrupt event as recorded most clearly in the Greenland ice cores. The initial meltwater pulse caused between 0.5 and 4 m of sea-level rise, based on estimates of lake volume and decaying ice cap size, values of 0. 4–1.2 m circulate. Based on sea-level data from the Mississippi Delta, the final stage of the Lake Agassiz–Ojibway drainage occurred at 8.31 to 8.18 ka. The sea-level data from the Rhine–Meuse Delta indicate a 2–4 m of near-instantaneous rise at 8. 54–8.2 ka, meltwater pulse sea-level rise was experienced fully at great distance from the release area. Gravity and rebound effects associated with the shifting of water meant that the sea-level fingerprint was smaller in areas closer to the Hudson Bay. The Mississippi delta records ≈20%, northwest Europe records ≈70% and Asia records ≈105% of the globally averaged amount, the cooling of the 8.2 kiloyear event was a temporary feature, however, the sea-level rise of the meltwater pulse was permanent. In 2003, the Office of Net Assessment at the United States Department of Defense was commissioned to produce a study on the likely and potential effects of a modern climate change. Bond event Antarctic Cold Reversal Little Ice Age Older Peron Piora Oscillation Sahara pump theory Younger Dryas Current sea level rise 5.9 kiloyear event 4.2 kiloyear event Storegga Slide
13.
Anno Domini
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The terms anno Domini and before Christ are used to label or number years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means in the year of the Lord, There is no year zero in this scheme, so the year AD1 immediately follows the year 1 BC. This dating system was devised in 525 by Dionysius Exiguus of Scythia Minor, the Gregorian calendar is the most widely used calendar in the world today. Traditionally, English followed Latin usage by placing the AD abbreviation before the year number, however, BC is placed after the year number, which also preserves syntactic order. The abbreviation is widely used after the number of a century or millennium. Because BC is the English abbreviation for Before Christ, it is sometimes concluded that AD means After Death. However, this would mean that the approximate 33 years commonly associated with the life of Jesus would not be included in either of the BC, astronomical year numbering and ISO8601 avoid words or abbreviations related to Christianity, but use the same numbers for AD years. The Anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate the years in his Easter table. His system was to replace the Diocletian era that had used in an old Easter table because he did not wish to continue the memory of a tyrant who persecuted Christians. The last year of the old table, Diocletian 247, was followed by the first year of his table. Thus Dionysius implied that Jesus Incarnation occurred 525 years earlier, without stating the year during which his birth or conception occurred. Blackburn & Holford-Strevens briefly present arguments for 2 BC,1 BC, There were inaccuracies in the list of consuls There were confused summations of emperors regnal years It is not known how Dionysius established the year of Jesuss birth. It is convenient to initiate a calendar not from the day of an event. For example, the Islamic calendar begins not from the date of the Hegira, at the time, it was believed by some that the Resurrection and end of the world would occur 500 years after the birth of Jesus. The old Anno Mundi calendar theoretically commenced with the creation of the based on information in the Old Testament. It was believed that, based on the Anno Mundi calendar, Anno Mundi 6000 was thus equated with the resurrection and the end of the world but this date had already passed in the time of Dionysius. The Anglo-Saxon historian the Venerable Bede, who was familiar with the work of Dionysius Exiguus, used Anno Domini dating in his Ecclesiastical History of the English People, completed in 731. e. On the continent of Europe, Anno Domini was introduced as the era of choice of the Carolingian Renaissance by the English cleric and scholar Alcuin in the late eighth century
14.
Kiloannus
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A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earths axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the globe, four seasons are recognized, spring, summer, autumn. In tropical and subtropical regions several geographical sectors do not present defined seasons, but in the seasonal tropics, a calendar year is an approximation of the number of days of the Earths orbital period as counted in a given calendar. The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a year of 366 days, as do the Julian calendars. For the Gregorian calendar the average length of the year across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a to represent a year of either 365 or 366 days, in English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time, it is defined as 365.25 days of exactly 86400 seconds, totalling exactly 31557600 seconds in the Julian astronomical year. The word year is used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year. Similarly, year can mean the period of any planet, for example. The term can also be used in reference to any long period or cycle, west Saxon ġēar, Anglian ġēr continues Proto-Germanic *jǣran. Cognates are German Jahr, Old High German jār, Old Norse ár and Gothic jer, all the descendants of the Proto-Indo-European noun *yeh₁rom year, season. Cognates also descended from the same Proto-Indo-European noun are Avestan yārǝ year, Greek ὥρα year, season, period of time, Old Church Slavonic jarŭ, Latin annus is from a PIE noun *h₂et-no-, which also yielded Gothic aþn year. Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, the Greek word for year, ἔτος, is cognate with Latin vetus old, from the PIE word *wetos- year, also preserved in this meaning in Sanskrit vat-sa- yearling and vat-sa-ras year. Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc. per annum means each year, anno Domini means in the year of the Lord. No astronomical year has an number of days or lunar months. Financial and scientific calculations often use a 365-day calendar to simplify daily rates, in the Julian calendar, the average length of a year is 365.25 days. In a non-leap year, there are 365 days, in a year there are 366 days
15.
Little Ice Age
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The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period. Although it was not an ice age, the term was introduced into scientific literature by François E. Matthes in 1939. It has been defined as a period extending from the 16th to the 19th centuries. Climatologists and historians working with local records no longer expect to agree on either the start or end dates of the period, which varied according to local conditions. The NASA Earth Observatory notes three particularly cold intervals, one beginning about 1650, another about 1770, and the last in 1850, at most, there was modest cooling of the Northern Hemisphere during the period. Hemispherically, the Little Ice Age can only be considered as a modest cooling of the Northern Hemisphere during this period of less than 1°C relative to late twentieth century levels. The IPCC Fourth Assessment Report of 2007 discusses more recent research and it states that when viewed together, the currently available reconstructions indicate generally greater variability in centennial time scale trends over the last 1 kyr than was apparent in the TAR. Given that the confidence levels surrounding all of the reconstructions are wide, the major differences between the various proxy reconstructions relate to the magnitude of past cool excursions, principally during the twelfth to fourteenth, seventeenth and nineteenth centuries. There is no consensus regarding the time when the Little Ice Age began, in the 13th century, pack ice began advancing southwards in the North Atlantic, as did glaciers in Greenland. Anecdotal evidence suggests expanding glaciers almost worldwide, in contrast, a climate reconstruction based on glacial length shows no great variation from 1600 to 1850 but strong retreat thereafter. The Little Ice Age ended in the half of the 19th century or early in the 20th century. The Little Ice Age brought colder winters to parts of Europe, farms and villages in the Swiss Alps were destroyed by encroaching glaciers during the mid-17th century. Canals and rivers in Great Britain and the Netherlands were frequently frozen deeply enough to support ice skating, freezing of the Golden Horn and the southern section of the Bosphorus took place in 1622. In 1658, a Swedish army marched across the Great Belt to Denmark to attack Copenhagen, Sea ice surrounding Iceland extended for miles in every direction, closing harbors to shipping. The population of Iceland fell by half, but that may have been caused by skeletal fluorosis after the eruption of Laki in 1783, Iceland also suffered failures of cereal crops and people moved away from a grain-based diet. Greenland was largely cut off by ice from 1410 to the 1720s, in Lisbon, Portugal, snowstorms were much more frequent than today, one winter in the 17th century produced eight snowstorms. Many springs and summers were cold and wet but with great variability between years and groups of years, crop practices throughout Europe had to be altered to adapt to the shortened, less reliable growing season, and there were many years of dearth and famine. According to Elizabeth Ewan and Janay Nugent, Famines in France 1693–94, Norway 1695–96, in Estonia and Finland in 1696–97, losses have been estimated at a fifth and a third of the national populations, respectively
16.
Migration Period
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The Migration Period was a time of widespread migrations within or into Europe in the middle of the first millennium AD. It has also been termed the Völkerwanderung and, from the Roman, many of the migrations were movements of Germanic, Slavic, and other peoples into the territory of the then Roman Empire, with or without accompanying invasions or war. Although immigration was common throughout the time of the Roman Empire, later invasions, also had significant effects, however, they are outside the scope of the Migration Period. Germanic peoples moved out of southern Scandinavia and Germany to the adjacent lands between the Elbe and Oder after 1000 BC. The first wave moved westward and southward, moving into southern Germany up to the Roman provinces of Gaul and Cisalpine Gaul by 100 BC and it is this western group which was described by the Roman historian Tacitus and Julius Caesar. A later wave of Germanic tribes migrated eastward and southward from Scandinavia between 600 and 300 BC to the opposite coast of the Baltic Sea, moving up the Vistula near the Carpathians, the Barbarian Invasions may be divided into two phases. The first phase, occurring between AD300 and 500, is documented by Greek and Latin historians but difficult to verify archaeologically. It puts Germanic peoples in control of most areas of what was then the Western Roman Empire, the Tervingi entered Roman territory in 376. Some time thereafter in Marcianopolis, the escort to Fritigern was killed while meeting with Lupicinus, fending off challenges from the Allemanni, Burgundians, and Visigoths, the Frankish kingdom became the nucleus of what would later become France and Germany. The initial Anglo-Saxon settlement of Britain occurred during the fifth century, the Burgundians settled in North Western Italy, Switzerland and Eastern France in the fifth century. The second phase took place between 500 and 700 and saw Slavic tribes settling in central and eastern Europe, gradually making it predominantly Slavic, additionally, Turkic tribes such as the Avars became involved in this phase. In 567, the Avars and the Lombards destroyed much of the Gepid Kingdom, the Lombards, a Germanic people, settled in Italy with their Herulian, Suebian, Gepid, Thuringian, Bulgarian, Sarmatian and Saxon allies in the 6th century. They were later followed by the Bavarians and the Franks, who conquered and ruled most of Italy, during the Khazar–Arab Wars, the Khazars stopped the Arab expansion into Europe across the Caucasus. At the same time, the Moors invaded Europe via Gibraltar and these battles broadly demarcated the frontiers between Christendom and Islam for the next millennium. The following centuries saw the Muslims successful in conquering most of Sicily from the Christians by 902, the Hungarian conquest of the Carpathian Basin from around 895, and the Viking expansion from the late 8th century conventionally mark the last large movements of the period. Christianity gradually converted the non-Islamic newcomers and integrated them into the medieval Christian order, a number of contemporary historical references worldwide refer to an extended period of extreme weather during 535–536. Evidence of this period is also found in dendrochronology and ice cores. The consequences of this period are debated
17.
Late Bronze Age collapse
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The palace economy of the Aegean Region and Anatolia that characterised the Late Bronze Age broke down to the isolated village cultures of the Greek Dark Ages. In the first phase of period, almost every city between Pylos and Gaza was violently destroyed, and many abandoned, examples include Hattusa, Mycenae. A very few states, particularly Assyria and Elam, were largely unaffected by the Bronze Age collapse. Before the Bronze Age collapse, Anatolia was dominated by a number of Indo-European peoples, Luwians, Hittites, Mitanni, and Mycenaean Greeks, together with the Semitic Assyrians, and Hurrians. From the 17th century BC, the Mitanni formed a ruling class over the Hurrians, similarly, the Hittites absorbed the Hattians, a people speaking a language that may have been of the North Caucasian group or a Language Isolate. Hattusas, the Hittite capital, was burned, abandoned, karaoğlan, near the present day city of Ankara, was burned and the corpses left unburied. Many other sites that were not destroyed were abandoned, the Hittite Empire was destroyed by the Indo-European-speaking Phrygians and by the Semitic-speaking Aramaeans. Troy was destroyed at least twice, before being abandoned until Roman times, other groups of Indo-European warriors followed into the region, most prominently the Lydians, the Cimmerians, and Scythians. The Semitic Arameans, Kartvelian-speaking Colchians, and Hurro-Urartuans also made an appearance in parts of the region, during the reign of the Hittite king Tudhaliya IV, the island was briefly invaded by the Hittites, either to secure the copper resource or as a way of preventing piracy. Shortly afterwards, the island was reconquered by his son around 1200 BC, some towns show traces of destruction at the end of LCII. Whether or not this is really an indication of a Mycenean invasion is contested, originally, two waves of destruction in c.1230 BC by the Sea Peoples and c.1190 BC by Aegean refugees have been proposed. The smaller settlements of Ayios Dhimitrios and Kokkinokremnos, as well as a number of sites, were abandoned. Kokkinokremos was a settlement, where various caches concealed by smiths have been found. That no one returned to reclaim the treasures suggests that they were killed or enslaved. Recovery occurred only in the Early Iron Age with Phoenician and Greek settlement and these sites in Cyprus show evidence of the collapse, Palaeokastro Kition Sinda Enkomi Ancient Syria had been initially dominated by a number of indigenous Semitic-speaking peoples. The East Semitic speaking Eblaites, the Canaanites language speaking Amorites, Syria during this time was known as The land of the Amurru. Levantine sites previously showed evidence of links with Mesopotamia, Egypt. Evidence, at Ugarit, shows that the destruction there occurred after the reign of Merneptah, the last Bronze Age king of the Semitic state of Ugarit, Ammurapi, was a contemporary of the Hittite king Suppiluliuma II
18.
4.2 kiloyear event
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The 4.2 kiloyear BP aridification event was one of the most severe climatic events of the Holocene period. Starting in about 2200 BC, it lasted the entire 22nd century BC. The drought may have initiated southeastward habitat tracking within the Indus Valley Civilization, however, this theory has been criticised by archaeologists, with political causes for the collapse of these polities thought to be more probable. A phase of intense aridity about 4.2 ka BP is recorded across North Africa, the Middle East, the Red Sea, the Arabian peninsula, the Indian subcontinent, glaciers throughout the mountain ranges of western Canada advanced at about this time. Evidence has also found in an Italian cave flowstone, the Kilimanjaro Ice sheet. The onset of the aridification in Mesopotamia about 4100 BP also coincided with an event in the North Atlantic. Despite this, evidence for the 4.2 kyr event in northern Europe is ambiguous, suggesting the origin, in c.2150 BC the Old Kingdom was hit by a series of exceptionally low Nile floods. It has been suggested that this may have impacted the collapse of the government in ancient Egypt at this time. Contemporary texts claim that famines, social disorder, and fragmentation subsequently occurred, after a phase of rehabilitation and restoration of order in various provinces, Egypt was eventually reunified within a new paradigm of kingship. The process of recovery depended on capable provincial administrators, a more formalised justice system, irrigation projects, the headwaters of the Tigris and Euphrates Rivers are fed by elevation-induced capture of winter Mediterranean rainfall. The Akkadian Empire in 2300 BC was the civilization to subsume independent societies into a single state. It has been claimed that the collapse of the state was influenced by a wide-ranging, centuries-long drought, archaeological evidence documents widespread abandonment of the agricultural plains of northern Mesopotamia and dramatic influxes of refugees into southern Mesopotamia around 2170 BC. A 180-km-long wall, the Repeller of the Amorites, was built across central Mesopotamia to stem nomadic incursions to the south. Around 2150 BC, the Gutian people, who inhabited the Zagros Mountains, defeated the demoralized Akkadian army, took Akkad. Widespread agricultural change in the Near East is visible at the end of the third millennium BC, resettlement of the northern plains by smaller sedentary populations occurred near 1900 BC, three centuries after the collapse. In the Persian Gulf region, there is a change in settlement pattern, style of pottery. The 22nd century BC drought marks the end of the Umm an-Nar Culture, on the Iberian peninsula, the construction of Motillas type settlements in the period after 2200 BCE is believed to be the consequence of severe aridification that affected this area. These were built during the Climatic Event 4.2 ka cal BP in a time of stress due to a period of severe
19.
Akkadian Empire
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The empire united all the Akkadian and Sumerian speakers under one rule. The Akkadian Empire controlled Mesopotamia, the Levant, and eastern and southern parts of Anatolia and Iran, sending military expeditions as far south as Dilmun and Magan in the Arabian Peninsula. During the 3rd millennium BC, there developed an intimate cultural symbiosis between the Sumerians and the Akkadians, which included widespread bilingualism. Akkadian gradually replaced Sumerian as a spoken language somewhere between the 3rd and the 2nd millennia BC, the Akkadian Empire reached its political peak between the 24th and 22nd centuries BC, following the conquests by its founder Sargon of Akkad. Under Sargon and his successors, the Akkadian language was imposed on neighboring conquered states such as Elam. Akkad is sometimes regarded as the first empire in history, though there are earlier Sumerian claimants, the Bible refers to Akkad in Genesis 10,10, which states that the beginning of Nimrods kingdom was in the land of Akkad. Nimrod is a Hebrew name not attested in Mesopotamians sources, many have pointed out similarities with the legend of Gilgamesh who founded Uruk, which is said to be the city Nimrod came to power. Today, some 7,000 texts from the Akkadian period alone are known, many later texts from the successor states of Assyria and Babylonia also deal with the Akkadian Empire. Understanding of the Akkadian Empire continues to be hampered by the fact that its capital Akkad has not yet been located, likewise, material that is thought to be Akkadian continues to be in use into the Ur III period. Many of the recent insights on the Akkadian Empire have come from excavations in the Upper Khabur area in modern northeastern Syria which was to become a part of Assyria after the fall of Akkad. For example, excavations at Tell Mozan brought to light a sealing of Taram-Agade, an unknown daughter of Naram-Sin. The excavators at nearby Tell Leilan have used the results from their investigations to argue that the Akkadian Empire came to an end due to a sudden drought, the so-called 4.2 kiloyear event. The impact of this event on Mesopotamia in general, and on the Akkadian Empire in particular. The Akkadian Period is contemporary with, EB IV, EB IVA and EJ IV, the absolute dates of their reigns are approximate. The Akkadian Empire takes its name from the region and city of Akkad, although the city of Akkad has not yet been identified on the ground, it is known from various textual sources. Among these is at least one text predating the reign of Sargon, together with the fact that the name Akkad is of non-Akkadian origin, this suggests that the city of Akkad may have already been occupied in pre-Sargonic times. Sargon of Akkad defeated and captured Lugal-Zage-Si in the Battle of Uruk, the earliest records in the Akkadian language date to the time of Sargon. Sargon was claimed to be the son of Laibum or Itti-Bel, a humble gardener, One legend related of Sargon in Assyrian times says that My mother was a changeling, my father I knew not
20.
Old Kingdom of Egypt
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The term itself was coined by eighteenth-century historians and the distinction between the Old Kingdom and the Early Dynastic Period is not one which would have been recognized by Ancient Egyptians. The Old Kingdom is most commonly regarded as the period from the Third Dynasty through to the Sixth Dynasty, many Egyptologists also include the Memphite Seventh and Eighth Dynasties in the Old Kingdom as a continuation of the administration centralized at Memphis. During the Old Kingdom, the king of Egypt became a god who ruled absolutely and could demand the services. Under King Djoser, the first king of the Third Dynasty of the Old Kingdom, the capital of Egypt was moved to Memphis. A new era of building was initiated at Saqqara under his reign, King Djosers architect, Imhotep is credited with the development of building with stone and with the conception of the new architectural form—the Step Pyramid. Indeed, the Old Kingdom is perhaps best known for the number of pyramids constructed at this time as burial places for Egypts kings. For this reason, the Old Kingdom is frequently referred to as the Age of the Pyramids, the first king of the Old Kingdom was Djoser of the third dynasty, who ordered the construction of a pyramid in Memphis necropolis, Saqqara. An important person during the reign of Djoser was his vizier and it was in this era that formerly independent ancient Egyptian states became known as nomes, under the rule of the king. The former rulers were forced to assume the role of governors or otherwise work in tax collection, Egyptians in this era worshipped their king as a god, believing that he ensured the annual flooding of the Nile that was necessary for their crops. Egyptian views on the nature of time during this period held that the worked in cycles. They also perceived themselves as a specially selected people, the Old Kingdom and its royal power reached a zenith under the Fourth Dynasty, which began with Sneferu. Using more stones than any king, he built three pyramids, a now collapsed pyramid in Meidum, the Bent Pyramid at Dahshur. However, the development of the pyramid style of building was reached not at Saqqara. Sneferu was succeeded by his son, Khufu who built the Great Pyramid of Giza, after Khufus death, his sons Djedefra and Khafra may have quarrelled. The latter built the pyramid and the Sphinx in Giza. Recent reexamination of evidence has led Egyptologist Vassil Dobrev to propose that the Sphinx had been built by Djedefra as a monument to his father Khufu, alternatively, the Sphinx has been proposed to be the work of Khafra and Khufu himself. There were military expeditions into Canaan and Nubia, with Egyptian influence reaching up the Nile into what is today the Sudan, the later kings of the Fourth Dynasty were king Menkaure, who built the smallest pyramid in Giza, Shepseskaf and, perhaps, Djedefptah. The Fifth Dynasty began with Userkaf and was marked by the importance of the cult of sun god Ra
21.
5.9 kiloyear event
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The 5.9 kiloyear event was one of the most intense aridification events during the Holocene Epoch. It is associated with the last round of the Sahara pump theory, a model by Claussen et al. suggested rapid desertification, associated with vegetation-atmosphere interactions following a cooling event, Bond event 4. For some reason, all the earlier events were followed by recovery. However, it appears that the 5.9 kiloyear event was followed by a recovery at best. The 5.9 kiloyear event was recorded as a cold event in the Erhai Lake sediments. In the eastern Arabian Peninsula, the 5.9 kiloyear event may have contributed to an increase in relatively greater social complexity and have corresponded to an end of the local Ubaid period, timeline of environmental history Bond event 4.2 kiloyear event 8.2 kiloyear event
22.
Glacier
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A glacier is a persistent body of dense ice that is constantly moving under its own weight, it forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs and they also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice, between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earths land surface, continental glaciers cover nearly 13,000,000 km2 or about 98 percent of Antarcticas 13,200,000 km2, with an average thickness of 2,100 m. Greenland and Patagonia also have huge expanses of continental glaciers, Glacial ice is the largest reservoir of fresh water on Earth. Within high altitude and Antarctic environments, the temperature difference is often not sufficient to release meltwater. A large piece of compressed ice, or a glacier, appears blue as large quantities of water appear blue and this is because water molecules absorb other colors more efficiently than blue. The other reason for the color of glaciers is the lack of air bubbles. Air bubbles, which give a color to ice, are squeezed out by pressure increasing the density of the created ice. The word Glaceon is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, the processes and features caused by or related to glaciers are referred to as glacial. The process of establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology, Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, and behavior, cirque glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier, a large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have a less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called ice sheets or continental glaciers, several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces, the only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of water, enough that if both melted, global sea levels would rise by over 70 m
23.
Norway
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The Antarctic Peter I Island and the sub-Antarctic Bouvet Island are dependent territories and thus not considered part of the Kingdom. Norway also lays claim to a section of Antarctica known as Queen Maud Land, until 1814, the kingdom included the Faroe Islands, Greenland, and Iceland. It also included Isle of Man until 1266, Shetland and Orkney until 1468, Norway has a total area of 385,252 square kilometres and a population of 5,258,317. The country shares a long border with Sweden. Norway is bordered by Finland and Russia to the north-east, Norway has an extensive coastline, facing the North Atlantic Ocean and the Barents Sea. King Harald V of the Dano-German House of Glücksburg is the current King of Norway, erna Solberg became Prime Minister in 2013, replacing Jens Stoltenberg. A constitutional monarchy, Norway divides state power between the Parliament, the Cabinet and the Supreme Court, as determined by the 1814 Constitution, the kingdom is established as a merger of several petty kingdoms. By the traditional count from the year 872, the kingdom has existed continuously for 1,144 years, Norway has both administrative and political subdivisions on two levels, counties and municipalities. The Sámi people have an amount of self-determination and influence over traditional territories through the Sámi Parliament. Norway maintains close ties with the European Union and the United States, the country maintains a combination of market economy and a Nordic welfare model with universal health care and a comprehensive social security system. Norway has extensive reserves of petroleum, natural gas, minerals, lumber, seafood, the petroleum industry accounts for around a quarter of the countrys gross domestic product. On a per-capita basis, Norway is the worlds largest producer of oil, the country has the fourth-highest per capita income in the world on the World Bank and IMF lists. On the CIAs GDP per capita list which includes territories and some regions, from 2001 to 2006, and then again from 2009 to 2017, Norway had the highest Human Development Index ranking in the world. It also has the highest inequality-adjusted ranking, Norway ranks first on the World Happiness Report, the OECD Better Life Index, the Index of Public Integrity and the Democracy Index. Norway has two names, Noreg in Nynorsk and Norge in Bokmål. The name Norway comes from the Old English word Norðrveg mentioned in 880, meaning way or way leading to the north. In contrasting with suðrvegar southern way for Germany, and austrvegr eastern way for the Baltic, the Anglo-Saxon of Britain also referred to the kingdom of Norway in 880 as Norðmanna land. This was the area of Harald Fairhair, the first king of Norway, and because of him
24.
Younger Dryas
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The Younger Dryas is a geological period from c.12,900 to c.11,700 calendar years ago. It is named after a genus, the alpine-tundra wildflower Dryas octopetala. Leaves of Dryas octopetala are occasionally abundant in the Late Glacial, often minerogenic-rich, the Younger Dryas saw a sharp decline in temperature over most of the northern hemisphere, at the end of the Pleistocene epoch, immediately preceding the current warmer Holocene. It was the most recent and longest of several interruptions to the warming of the Earths climate since the severe Last Glacial Maximum. The Younger Dryas was a period of change, but the effects were complex. In the southern hemisphere, and some areas of the such as southeastern North America. The presence of a cold period at the end of the Late Glacial interval has been known for a long time. Paleobotanical and lithostratigraphic studies of Swedish and Danish bog and lake sites, e. g. the Allerød clay pit in Denmark, first recognized and described the Younger Dryas. The Younger Dryas is the youngest and longest of three stadials that resulted from typically abrupt climatic changes that took place over the last 16,000 calendar years. This is not securely dated, and estimates vary by 400 years, in northern Scotland the glaciers were thicker and more extensive than during the Younger Dryas. The Older Dryas, in turn, is preceded by another warmer stage and this stadial is often, but not always, known as the Oldest Dryas. The Oldest Dryas occurred approximately 1,770 calendar years before the Younger Dryas, according to the GISP2 ice core from Greenland, the Oldest Dryas occurred between about 15,070 and 14,670 calendar years BP. In Ireland, the Younger Dryas has also known as the Nahanagan Stadial. In the Greenland Summit ice core chronology, the Younger Dryas corresponds to Greenland Stadial 1, the preceding Allerød warm period is subdivided into three events, Greenland Interstadial-1c to 1a. This drastic change in vegetation is typically interpreted to be an effect of a decrease in temperature. In sharp contrast to the warming of the preceding Older Dryas interstadial and it has been inferred that its end occurred over a period of a decade or so, but the onset may have been faster. Thermally fractionated nitrogen and argon isotope data from Greenland ice core GISP2 indicate that the summit of Greenland was approximately 15 °C colder during the Younger Dryas than today. Nothing of the size, extent, or rapidity of this period of climate change has been experienced since its end
25.
Boreal (age)
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In peat bog sediments, the Boreal is also recognized by its characteristic pollen zone. It was preceded by the Younger Dryas, the last cold snap of the Pleistocene, and followed by the Atlantic, the Boreal, transitional between the two periods, varied a great deal, at times comprising within it climates like todays. Subsequent to the original Blytt-Sernander scheme, the first stage of the Boreal was divided off as a Pre-boreal transitional phase, some current schemes based on pollen zones also distinguish a pre-Boreal, an early Boreal and a late Boreal. The generally accepted date for the end of the Younger Dryas, the start of the period is relatively sharply defined by a rise of 7 °C in 50 years. The date is based fairly solidly on Greenland ice cores, which give 11,640 BP for the late Younger Dryas and 11,400 BP for the early Pre-Boreal, but estimates of other dates vary by up to 1000 years, for a number of reasons. First, Boreal can identify a paleoclimate, a zone or a temporally-fixed chronozone. Second, different dating methods obtain different dates, the underlying problem is that climate and pollen vary somewhat from region to region. The scientists of each use the methods available in their region, whether lake varves. Standardization has become of increasing concern to scientists everywhere, dates from many methods continue to multiply as paleoclimatologists seek higher resolution. But it is unclear whether regional variation will allow high-resolution standardization, yet, there are some solid dates of the Pre-Boreal and Boreal. The Saksunarvatn tephra is dated in Greenland ice to 10, 180±60 BP, in deposits at Krakenes in Norway, to 10, 010–9,980 years BP calibrated, in northwest German lakes. The tephra occurs in early Boreal contexts, so, it seems certain that the early Boreal includes the year 10,000 BP. Similarly, the late Boreal includes the Kilian/Vasset tephra of Swiss and southwest German lakes at 8200 BP, but the borders are less certain. Studies of bogs in northwest Russia are the basis for a division of the PreBoreal into PB-1,10, 000-9800, the scheme goes on to divide the Boreal into BO-1, 9300–9000, BO-2, 9000–8500, and BO-3, 8500–8000, incal. CalPal used on these dates suggests overall boundaries of 11,500 and 10,500 BP for the Pre-Boreal, dates given recently are usually earlier than those given more than 10 years ago. For example, Iverson and Rud give dates of 10, 000–9000 BP for the PreBoreal and 9000–8000 BP for the Boreal, presumably, more-recent dates are more accurate, as technology improves with time, often quite rapidly. Yet, pollen and climate phases also to some degree may depend on latitude, scientists look for the overall pattern of the dates, but that technique is not 100% reliable, either. Large numbers of herbivores wandered in herds over vast distances, the blanket teemed with small, rapidly reproducing species, which supported food chains of larger predators
26.
Ice-sheet dynamics
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Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose activity is controlled by two main variable factors, the temperature and strength of their bases. A number of processes alter these two factors, resulting in cyclic surges of activity interspersed with periods of inactivity, on both hourly and centennial time scales. Ice-sheet dynamics are of interest in modelling future sea level rise, the main cause of flow within glaciers can be attributed to an increase in the surface slope, brought upon by an imbalance between the amounts of accumulation vs. ablation. This imbalance increases the stress on a glacier until it begins to flow. The flow velocity and deformation will increase as the line between these two processes is approached, but are also affected by the slope of the ice, the ice thickness. When the amount of strain is proportional to the stress being applied, at this point the glacier will begin to deform under its own weight and flow across the landscape. Velocity increases inward toward the line and upward, as the amount of deformation decreases. The highest flow velocities are found at the surface, representing the sum of the velocities of all the layers below. Glaciers may also move by sliding, where the base of the glacier is lubricated by meltwater. Meltwater may be produced by pressure-induced melting, friction or geothermal heat, the more variable the amount of melting at surface of the glacier, the faster the ice will flow. The top 50 meters of the form the fracture zone. Cracks form as the glacier moves over irregular terrain, which may penetrate the depth of the fracture zone. Most of the important processes controlling glacial motion occur in the ice-bed contact—even though it is only a few meters thick, glaciers will move by sliding when the basal shear stress drops below the shear resulting from the glaciers weight. τD = ρgh sin α where τD is the driving stress, τB is the basal shear stress, a function of bed temperature and softness. τF, the stress, is the lower of τB. It controls the rate of flow, as per the figure. For a given glacier, the two variables are τD, which varies with h, the depth of the glacier, and τB, the basal shear stress is a function of three factors, the beds temperature, roughness and softness
27.
PubMed Identifier
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PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine at the National Institutes of Health maintains the database as part of the Entrez system of information retrieval, from 1971 to 1997, MEDLINE online access to the MEDLARS Online computerized database primarily had been through institutional facilities, such as university libraries. PubMed, first released in January 1996, ushered in the era of private, free, home-, the PubMed system was offered free to the public in June 1997, when MEDLINE searches via the Web were demonstrated, in a ceremony, by Vice President Al Gore. Information about the journals indexed in MEDLINE, and available through PubMed, is found in the NLM Catalog. As of 5 January 2017, PubMed has more than 26.8 million records going back to 1966, selectively to the year 1865, and very selectively to 1809, about 500,000 new records are added each year. As of the date,13.1 million of PubMeds records are listed with their abstracts. In 2016, NLM changed the system so that publishers will be able to directly correct typos. Simple searches on PubMed can be carried out by entering key aspects of a subject into PubMeds search window, when a journal article is indexed, numerous article parameters are extracted and stored as structured information. Such parameters are, Article Type, Secondary identifiers, Language, publication type parameter enables many special features. As these clinical girish can generate small sets of robust studies with considerable precision, since July 2005, the MEDLINE article indexing process extracts important identifiers from the article abstract and puts those in a field called Secondary Identifier. The secondary identifier field is to store numbers to various databases of molecular sequence data, gene expression or chemical compounds. For clinical trials, PubMed extracts trial IDs for the two largest trial registries, ClinicalTrials. gov and the International Standard Randomized Controlled Trial Number Register, a reference which is judged particularly relevant can be marked and related articles can be identified. If relevant, several studies can be selected and related articles to all of them can be generated using the Find related data option, the related articles are then listed in order of relatedness. To create these lists of related articles, PubMed compares words from the title and abstract of each citation, as well as the MeSH headings assigned, using a powerful word-weighted algorithm. The related articles function has been judged to be so precise that some researchers suggest it can be used instead of a full search, a strong feature of PubMed is its ability to automatically link to MeSH terms and subheadings. Examples would be, bad breath links to halitosis, heart attack to myocardial infarction, where appropriate, these MeSH terms are automatically expanded, that is, include more specific terms. Terms like nursing are automatically linked to Nursing or Nursing and this important feature makes PubMed searches automatically more sensitive and avoids false-negative hits by compensating for the diversity of medical terminology. The My NCBI area can be accessed from any computer with web-access, an earlier version of My NCBI was called PubMed Cubby
28.
Science (journal)
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Science, also widely referred to as Science Magazine, is the peer-reviewed academic journal of the American Association for the Advancement of Science and one of the worlds top academic journals. It was first published in 1880, is circulated weekly and has a print subscriber base of around 130,000. Because institutional subscriptions and online access serve an audience, its estimated readership is 570,400 people. Unlike most scientific journals, which focus on a field, Science. According to the Journal Citation Reports, Sciences 2015 impact factor was 34.661, although it is the journal of the AAAS, membership in the AAAS is not required to publish in Science. Papers are accepted from authors around the world, competition to publish in Science is very intense, as an article published in such a highly cited journal can lead to attention and career advancement for the authors. Fewer than 7% of articles submitted are accepted for publication, Science is based in Washington, D. C. United States, with an office in Cambridge, England. Science was founded by New York journalist John Michels in 1880 with financial support from Thomas Edison, however, the journal never gained enough subscribers to succeed and ended publication in March 1882. Entomologist Samuel H. Scudder resurrected the journal one year later and had some success while covering the meetings of prominent American scientific societies, however, by 1894, Science was again in financial difficulty and was sold to psychologist James McKeen Cattell for $500. In an agreement worked out by Cattell and AAAS secretary Leland O. Howard, after Cattell died in 1944, the ownership of the journal was transferred to the AAAS. After Cattells death in 1944, the journal lacked a consistent editorial presence until Graham DuShane became editor in 1956. In 1958, under DuShanes leadership, Science absorbed The Scientific Monthly, physicist Philip Abelson, a co-discoverer of neptunium, served as editor from 1962 to 1984. Under Abelson the efficiency of the process was improved and the publication practices were brought up to date. During this time, papers on the Apollo program missions and some of the earliest reports on AIDS were published, biochemist Daniel E. Koshland, Jr. served as editor from 1985 until 1995. From 1995 until 2000, neuroscientist Floyd E. Bloom held that position, biologist Donald Kennedy became the editor of Science in 2000. Biochemist Bruce Alberts took his place in March 2008, geophysicist Marcia McNutt became editor-in-chief in June 2013. During her tenure the family of journals expanded to include Science Robotics and Science Immunology, jeremy M. Berg became editor-in-chief on July 1,2016
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International Standard Serial Number
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An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication. The ISSN is especially helpful in distinguishing between serials with the same title, ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization international standard in 1971, ISO subcommittee TC 46/SC9 is responsible for maintaining the standard. When a serial with the content is published in more than one media type. For example, many serials are published both in print and electronic media, the ISSN system refers to these types as print ISSN and electronic ISSN, respectively. The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers, as an integer number, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a check digit. Formally, the form of the ISSN code can be expressed as follows, NNNN-NNNC where N is in the set, a digit character. The ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, for calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, the modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, ISSN codes are assigned by a network of ISSN National Centres, usually located at national libraries and coordinated by the ISSN International Centre based in Paris. The International Centre is an organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, at the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept, where ISBNs are assigned to individual books, an ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an identifier associated with a serial title. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change, separate ISSNs are needed for serials in different media. Thus, the print and electronic versions of a serial need separate ISSNs. Also, a CD-ROM version and a web version of a serial require different ISSNs since two different media are involved, however, the same ISSN can be used for different file formats of the same online serial
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Geology (journal)
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Geology is a publication of the Geological Society of America. The GSA claims that it is the most widely read journal in the field of earth science. It is published monthly, with each issue containing 20 or more articles, one of the goals of the journal is to provide a forum for shorter articles and less focus on pure academic research type articles. List of scientific journals List of scientific journals in earth and atmospheric sciences Official website Archives Table of contents for current edition
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Climate oscillation
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A climate oscillation or climate cycle is any recurring cyclical oscillation within global or regional climate, and is a type of climate pattern. They are not perfectly periodic and a Fourier analysis of the data does not give a sharp spectrum, records of past climate conditions are recovered through geological examination of proxies, found in glacier ice, sea bed sediment, tree ring studies or otherwise. Many oscillations on different time-scales are hypothesized, although the causes may be unknown, the Interdecadal Pacific Oscillation –15 to 30 years. The Arctic oscillation – no particular periodicity the North Atlantic Oscillation – no particular periodicity the North Pacific Oscillation –. In the case of volcanoes, large eruptions such as Mount Tambora in 1816, around 70000 years ago the Toba supervolcano eruption created an especially cold period during the ice age, leading to a possible genetic bottleneck in human populations. However, outgassing from large igneous provinces such as the Permian Siberian Traps can input carbon dioxide into the atmosphere, triggering of other mechanisms, such as methane clathrate deposits as during the Paleocene-Eocene Thermal Maximum, increased the rate of climatic temperature change and oceanic extinctions. Another longer-term near-millennial oscillation involves the Daansgard-Oeschger cycles, occurring on roughly 1 and they may be related to the Holocene Bond events, and may involve factors similar to those responsible for Heinrich events. There are close correlations between Earths climate oscillations and astronomical factors, and modes of heat distribution between the climate system. Shorter-term climate oscillations typically do not directly result in climate change in temperatures. Collapses of past civilizations such as the Maya may be related to cycles of precipitation, especially drought, one example of possible correlations between factors affecting the climate and global events, popular with the media, is a 2003 study on the correlation between wheat prices and sunspot numbers. Radiative forcings and other factors in a climate oscillation must obey the laws of atmospheric thermodynamics, however, because Earths climate is inherently a complex system, simple Fourier analysis or climate modelling often does not create a perfect replication of the observed or inferred conditions. No climate cycle is found to be periodic, although the Milankovich cycles are quite close to being periodic. One difficulty in detecting climate cycles is that the Earths climate has been changing in non-cyclic ways over most paleoclimatological timescales, for instance, we are now in a period of global warming that appears anthropogenic. During warm periods, temperature fluctuations are often of a lesser amplitude, the Pleistocene period, dominated by repeated glaciations, developed out of more stable conditions in the Miocene and Pliocene climate. Holocene climate has been relatively stable, all of these changes complicate the task of looking for cyclical behavior in the climate. Most climatologists recognize the existence of various tipping points that push small forcings beyond a threshold that makes the change irreversible while the forcings are still in place. Various climate forcings are typically in flux throughout geologic time, however, the absence of plant cover to absorb atmospheric CO2 emitted by volcanoes meant that the greenhouse gas could accumulate in the atmosphere. There was also an absence of exposed rocks, which use CO2 when they undergo weathering
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Arctic oscillation
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When the AO index is positive, surface pressure is low in the polar region. This helps the middle latitude jet stream to blow strongly and consistently from west to east, when the AO index is negative, there tends to be high pressure in the polar region, weaker zonal winds, and greater movement of frigid polar air into middle latitudes. This zonally symmetric seesaw between sea level pressures in polar and temperate latitudes was first identified by Edward Lorenz and named in 1998 by David W. J. Thompson, over most of the past century, the Arctic Oscillation alternated between its positive and negative phases. Starting in the 1970s the oscillation has trended to more of a phase when averaged using a 60-day running mean. In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, weather patterns in the negative phase are in general opposite to those of the positive phase. Climatologists are now routinely invoking the Arctic Oscillation in their official public explanations for extremes of weather, a very persistent, strong ridge of high pressure, or blocking system, near Greenland allowed cold Arctic air to slide south into Europe. Europe was not the region in the Northern Hemisphere affected by the Arctic Oscillation. A large snow storm and frigid temperatures affected much of the Midwest United States on December 10–13, a further, quite graphic illustration of the effects of the negative phase of the oscillation occurred in February 2010. In that month, the Arctic Oscillation reached its most negative monthly mean value, −4.266 and that month was characterized by three separate historic snowstorms that occurred in the mid-Atlantic region of the United States. The first storm dumped 25 inches on Baltimore, Maryland, on February 5–6, in New York City, a separate storm deposited 20.9 inches on February 25–26. This kind of activity is as anomalous and extreme as the negative AO value itself. Similarly, the greatest negative value for the AO since 1950 in January was −3.767 in 1977, Baltimore, and many other mid-Atlantic locations in that span of time. And though the January AO has been negative only 60. 6% of the time between 1950 and 2010,9 of the 10 coldest Januarys in New York City since 1950 have coincided with negative AOs. However, the correlation between sharply negative Arctic Oscillations and excessive winter cold and snow in regions vulnerable in that way to these negative AOs should not be overstated and it is by no means a simple, one-to-one equivalence. An extreme Arctic Oscillation does not necessarily mean extreme weather will occur, for example, since 1950, eight out of the 10 coldest Januarys in New York did not coincide with the 10 lowest January AO values. And the fourth warmest January there since 1950 coincided with one of those 10 most negative AOs, further, the precise value of the AO index only imperfectly reflects the severity of the weather associated with it
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Atlantic multidecadal oscillation
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The Atlantic Multidecadal Oscillation is a climate cycle that affects the sea surface temperature of the North Atlantic Ocean based on different modes on multidecadal timescales. The Atlantic Multidecadal Oscillation was identified by Schlesinger and Ramankutty in 1994, the AMO signal is usually defined from the patterns of SST variability in the North Atlantic once any linear trend has been removed. This detrending is intended to remove the influence of greenhouse gas-induced global warming from the analysis, however, if the global warming signal is significantly non-linear in time, variations in the forced signal will leak into the AMO definition. Consequently, correlations with the AMO index may mask effects of global warming, several methods have been proposed to remove the global trend and ENSO influence over the North Atlantic SST. Ting et al. however argue that the forced SST pattern is not spatially uniform, they separated the forced, van Oldenborgh et al. derived an AMO index as the SST averaged over the extra-tropical North Atlantic minus the regression on global mean temperature. Guan and Nigam removed the non stationary global trend and Pacific natural variability before applying an EOF analysis to the residual North Atlantic SST, in models, AMO-like variability is associated with small changes in the North Atlantic branch of the Thermohaline Circulation. However, historical oceanic observations are not sufficient to associate the derived AMO index to present-day circulation anomalies, the Atlantic Multidecadal Oscillation is important for how external forcings are linked with North Atlantic SSTs. The AMO index is correlated to air temperatures and rainfall over much of the Northern Hemisphere, in particular in the climate in North America. Through changes in circulation, the AMO can also modulate spring snowfall over the Alps. Rainfall patterns are affected in North Eastern Brazilian and African Sahel and it is also associated with changes in the frequency of North American droughts and is reflected in the frequency of severe Atlantic hurricane activity. Recent research suggests that the AMO is related to the past occurrence of droughts in the US Midwest. When the AMO is in its phase, these droughts tend to be more frequent or prolonged. Two of the most severe droughts of the 20th century occurred during the positive AMO between 1925 and 1965, The Dust Bowl of the 1930s and the 1950s drought, Florida and the Pacific Northwest tend to be the opposite—warm AMO, more rainfall. Climate models suggest that a phase of the AMO strengthens the summer rainfall over India and Sahel. Paleoclimatologic studies have confirmed this pattern—increased rainfall in AMO warmphase, decreased in cold phase—for the Sahel over the past 3,000 years, in viewing actual data on a short time horizon, sparse experience would suggest the frequency of major hurricanes is not strongly correlated with the AMO. During warm phases of the AMO, the number of minor hurricanes saw a modest increase, the hurricane activity index is found to be highly correlated with the Atlantic multidecadal oscillation. If there is an increase in hurricane activity connected to global warming, the AMO alternately obscures and exaggerates the global increase in temperatures due to human-induced global warming. Based on the duration of negative and positive phases of the AMO
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Axial tilt
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In astronomy, axial tilt, also known as obliquity, is the angle between an objects rotational axis and its orbital axis, or, equivalently, the angle between its equatorial plane and orbital plane. At an obliquity of zero, the two axes point in the direction, i. e. the rotational axis is perpendicular to the orbital plane. Over the course of an orbit, the obliquity usually does not change considerably, and this causes one pole to be directed more toward the Sun on one side of the orbit, and the other pole on the other side — the cause of the seasons on the Earth. Earths obliquity oscillates between 22.1 and 24.5 degrees on a 41, 000-year cycle, the mean obliquity is currently 23°26′13. 4″. There are two methods of specifying tilt. The IAU also uses the rule to define a positive pole for the purpose of determining orientation. Using this convention, Venus is tilted 177° and it is denoted by the Greek letter ε. Earth currently has a tilt of about 23. 4°. This value remains about the relative to a stationary orbital plane throughout the cycles of axial precession. But the ecliptic due to planetary perturbations, and the obliquity of the ecliptic is not a fixed quantity. At present, it is decreasing at a rate of about 47″ per century, Earths obliquity may have been reasonably accurately measured as early as 1100 BC in India and China. The ancient Greeks had good measurements of the obliquity since about 350 BC, about 830 AD, the Caliph Al-Mamun of Baghdad directed his astronomers to measure the obliquity, and the result was used in the Arab world for many years. It was widely believed, during the Middle Ages, that both precession and Earths obliquity oscillated around a value, with a period of 672 years. Earths axis remains tilted in the direction with reference to the background stars throughout a year. This means that one pole will be directed away from the Sun at one side of the orbit and this is the cause of Earths seasons. Summer occurs in the Northern hemisphere when the pole is directed toward the Sun. Variations in Earths axial tilt can influence the seasons and is likely a factor in climate change. The exact angular value of the obliquity is found by observation of the motions of Earth, from 1984, the Jet Propulsion Laboratorys DE series of computer-generated ephemerides took over as the fundamental ephemeris of the Astronomical Almanac
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Diurnal temperature variation
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Atmospheric temperature range is the numerical difference between the minimum and maximum values of temperature observed in a given location during a period of time or the average. The variation in temperature occurs from the highs of the day to the cool of nights is called diurnal temperature variation. Average yearly temperature is 22.4 degrees Celsius, ranging from a minimum of 12.2 degrees to a maximum of 29.9 degrees. The average temperature range is 11.4 degrees, variability along the year is small. It is easy to see in the graph another typical phenomenon of temperature ranges, in Campinas, for example, the daily temperature range in July may vary between typically 10 and 24 degrees Celsius, while in January, it may range between 20 and 30 degrees Celsius. The effect of latitude, tropical climate, constant gentle wind and sea-side locations show smaller average temperature ranges, smaller variations of temperature, average maximum yearly temperature is 28.7 degrees Celsius and average minimum is 21.9. The average temperature range is 5.7 degrees only, temperature variation along the year in Aracaju is very damped. Most of the places with these characteristics are located in the transition between temperate and tropical climates, approximately around the tropics, particularly in the Southern hemisphere, the minimum temperature at night does not occur on the ground but few tens of centimeters above the ground. The phenomenon is attributed to the interaction of radiation effects on atmospheric aerosols
. PMID 18772385.