- Pokémon Detective Pikachu (film by Letterman [2019])
Ryan Reynolds: Hollywood career: >Pokémon Detective Pikachu (2019). Exhibiting his skill for self-mockery, he played himself in an episode of Seth MacFarlane’s series Family Guy (2011) and made memorable cameo appearances in MacFarlane’s feature comedies Ted (2012) and A Million Ways to Die in the West (2014).
- Pokémon GO (mobile electronic game)
Pokémon: The mobile application Pokémon GO was a blockbuster success upon its release in 2016. Developed by Niantic Labs, a former division of Google, the game used GPS data and the mobile device’s camera to create an “augmented reality” that allowed users to capture Pokémon from real-life locations.
- poker (card game)
poker, card game, played in various forms throughout the world, in which a player must call (i.e., match) the bet, raise (i.e., increase) the bet, or concede (i.e., fold). Its popularity is greatest in North America, where it originated. It is played in private homes, in poker clubs, in casinos,
- poker (fire tool)
fireplace: The poker, designed to break burning coal into smaller pieces, did not become common until the 18th century. Coal scuttles appeared early in the 18th century and were later adapted into usually ornamental wood boxes or racks for fire logs. The fire screen was developed early…
- poker dice (dice game)
poker dice, game involving five dice specially marked to simulate a playing-card deck’s top six cards (ace, king, queen, jack, 10, 9). The object is to throw a winning poker hand, with hands ranking as in poker except that five of a kind is high and there are no flushes. After a player’s first
- Poker Face (song by Lady Gaga)
Lady Gaga: Success: The Fame and The Fame Monster: …other singles off The Fame—“Poker Face,” “LoveGame,” and “Paparazzi”—also reached number one on the radio chart, making Lady Gaga the first artist in the 17-year history of that chart to have four number ones from a debut album. The Fame was well received critically and proved enormously successful commercially,…
- poker machine (gambling device)
slot machine, gambling device operated by dropping one or more coins or tokens into a slot and pulling a handle or pushing a button to activate one to three or more reels marked into horizontal segments by varying symbols. The machine pays off by dropping into a cup or trough from two to all the
- pokeweed (plant)
pokeweed, (Phytolacca americana), strong-smelling plant with a poisonous root resembling that of a horseradish. Pokeweed is native to wet or sandy areas of eastern North America. The berries contain a red dye used to colour wine, candies, cloth, and paper. Mature stalks, which are red or purplish
- pokeweed family (plant family)
Phytolaccaceae, the pokeweed family of flowering plants, comprising 18 genera and 65 species of herbs, shrubs, and trees, mostly native to tropical and subtropical North America and Africa. Leaves are spiral, simple, and entire (i.e., smooth-edged). Flowers are typically arranged in branched or
- Pokharā Valley (valley, Nepal)
Nepal: Drainage: …by the Seti River, the Pokharā Valley, 96 miles west of Kathmandu, is also a flat lacustrine basin. There are a few remnant lakes in the Pokharā basin, the largest being Phewa Lake, which is about two miles long and nearly a mile wide. North of the basin lies the…
- Pokhran (city, India)
nuclear weapon: India: …May 18, 1974, at the Pokhran test site on the Rajasthan Steppe, India, detonated a nuclear device with a yield later estimated to be less than 5 kilotons. (A figure of 12 kilotons was announced by India at the time.) India characterized the underground test as being for peaceful purposes,…
- Pokolenie (film by Wajda)
Andrzej Wajda: His debut feature, Pokolenie (1955; A Generation), together with Kanał (1957; “Canal”) and Popiół i diament (1958; Ashes and Diamonds), constituted a popular trilogy that is considered to have launched the Polish film school. The movies deal in symbolic imagery with sweeping social and political changes in Poland during the…
- Pokolenie zimy (novel by Aksyonov)
Vasily Aksyonov: Pokolenie zimy (1994; Generations of Winter) chronicles the fate of a family of intellectuals at the hands of the Soviet regime during the period of Joseph Stalin’s rule.
- Pokomam (people)
Pocomam, Mayan Indians of the highlands of eastern Guatemala. The Pocomam are primarily agriculturists; they cultivate corn (maize) and beans and manufacture pottery and charcoal. Houses are built of poles or adobe, with thatch, tile, or tin roofs. The houses are scattered over the countryside,
- Pokorny, Julius (European linguist)
Julius Pokorny was a European linguist known for his work in Celtic studies and Indo-European etymological research. Pokorny was a professor at the University of Berlin from 1920 until 1935/36 and taught subsequently in Switzerland, holding lectureships at the University of Bern from 1944 to 1948
- Pokorovskaya Church (church, Kizhi Island, Russia)
Kizhi Island: The Pokorovskaya (Intercession) Church (1764) has 10 cupolas, and its interior is decorated with icons made locally in the 17th and 18th centuries. St. Lazarus, the oldest church (built 1390) in the Karelian republic, was transported to the open-air museum from the Murom Monastery in the…
- Pokou, Laurent (Ivorian athlete)
Africa Cup of Nations: …Nations (18), and Ivorian striker Laurent Pokou, who tallied five goals in a 6–1 victory over Ethiopia in 1970.
- Pokrovsk (Russia)
Lena River: Physiography: …(640 km), from Olyokminsk to Pokrovsk (60 miles [100 km] above Yakutsk), the Lena flows along the bottom of a narrow valley with sheer, broken slopes. The enormous limestone rock formations sometimes resemble the ruins of castles, or columns, or the figures of people and animals; and the area is…
- Pokrovskaya (Russia)
Engels, city, Saratov oblast (province), western Russia. The city is situated on the left bank of the Volga River, opposite Saratov, to which it is connected by a highway bridge (completed 1965). Founded in 1747 as Pokrovskaya sloboda (military settlement), the city was the capital of the former
- Pokrovsky Cathedral (church, Moscow, Russia)
Saint Basil the Blessed, church constructed on Red Square in Moscow between 1554 and 1560 by Tsar Ivan IV (the Terrible), as a votive offering for his military victories over the khanates of Kazan and Astrakhan. The church was dedicated to the protection and intercession of the Virgin, but it came
- Pokrovsky Cathedral (church, Kharkiv, Ukraine)
Kharkiv: …the past are the 17th-century Pokrovsky Cathedral, the 19th-century Patriarchal Cathedral, and the belltower commemorating the victory over Napoleon I in 1812.
- Pokrovsky Sobor (church, Moscow, Russia)
Saint Basil the Blessed, church constructed on Red Square in Moscow between 1554 and 1560 by Tsar Ivan IV (the Terrible), as a votive offering for his military victories over the khanates of Kazan and Astrakhan. The church was dedicated to the protection and intercession of the Virgin, but it came
- Pokrovsky, Mikhail Nikolayevich (Soviet historian)
Mikhail Nikolayevich Pokrovsky was a Soviet historian and government official, one of the most representative Russian Marxist historians. Pokrovsky joined the revolutionary movement as a young man, becoming a member of the Bolshevik Party in 1905. Forced to leave Russia following the revolutionary
- Pol Pot (Cambodian political leader)
Pol Pot was a Khmer political leader who led the Khmer Rouge totalitarian regime (1975–79) in Cambodia that imposed severe hardships on the Cambodian people. His radical communist government forced the mass evacuations of cities, killed or displaced millions of people, and left a legacy of
- Pol’ana (mountains, Europe)
Carpathian Mountains: Physiography of the Carpathian Mountains: …the largest among them is Pol’ana (4,784 feet).
- Pol, Santiago (Venezuelan graphic designer)
graphic design: Graphic design in developing nations: …poster (1992) by Venezuelan designer Santiago Pol utilizes clear symbolic forms within a highly sophisticated spatial configuration, both elements of Modernist graphic design. In this work, dynamic shapes signify three peppers, symbols that are redolent with regional symbolism; the central pepper is formed by the white, or negative, space between…
- Polā (Hindu festival)
Maharashtra: Recreation: During Pola in August, farmers bathe, decorate, and parade their bulls through the streets, signifying the start of the sowing season. The festival Ganesh Chaturthi, celebrating the birth of Hindu deity Ganesha, is held during the rainy season and is by far the most popular in…
- Pola (Croatia)
Pula, major port and industrial centre in western Croatia. It lies at the southern tip of Istria (peninsula) at the head of the Bay of Pula and has a large, almost landlocked harbour in which there is a naval base and the Uljanik shipyards. Conquered by Rome in the 2nd century bce, Pula by the 2nd
- Pola de Siero (town, Spain)
Pola de Siero, town, north-central Asturias provincia (province) and comunidad autónoma (autonomous community), northwestern Spain. It lies on the Nora River, just northeast of Oveido city. Chartered in 1270 by Alfonso X of Castile, it is now a meatpacking centre, with brewing and tanning
- Polab (people)
Polab, member of the westernmost Slavs of Europe who dwelt in medieval times in the territory surrounded by the lower Elbe River in the west, the Baltic Sea in the north, the lower Oder River in the east, and Lusatia in the south. (This territory was situated in what later became Germany.) Their
- Polabí (plateau, Czech Republic)
Czech Republic: Relief: …roughly ovoid elevated basin (the Bohemian Plateau) encircled by mountains divided into six major groups. In the southwest are the Šumava Mountains, which include the Bohemian Forest (Böhmerwald). In the west are the Berounka River highlands. In the northwest, the Ore Mountains (Czech: Krušné hory; German: Erzgebirge) form the frontier…
- Polabian language
Lekhitic languages: The extinct Polabian language, which bordered the Sorbian dialects in eastern Germany, was spoken by the Slavic population of the Elbe River region until the 17th or 18th century; a dictionary and some phrases written in the language exist.
- Polacolor process (photography)
technology of photography: The Polacolor process: Polaroid colour film has a larger number of active layers, including a blue-sensitive silver halide emulsion backed by a layer consisting of a yellow dye–developer compound, a green-sensitive layer backed by a layer of magenta dye–developer, and a red-sensitive layer backed by a…
- Polamalu, Troy (American football player)
Troy Polamalu is considered one of the best defensive backs of the early 21st century. Known for his speed, agility, and hard-hitting style, Polamalu played for the Pittsburgh Steelers of the National Football League (NFL) and was part of the teams that won the Super Bowl championships in 2006 and
- Polamalu, Troy Aumua (American football player)
Troy Polamalu is considered one of the best defensive backs of the early 21st century. Known for his speed, agility, and hard-hitting style, Polamalu played for the Pittsburgh Steelers of the National Football League (NFL) and was part of the teams that won the Super Bowl championships in 2006 and
- Poland
Poland, country of central Europe. Poland is located at a geographic crossroads that links the forested lands of northwestern Europe and the sea lanes of the Atlantic Ocean to the fertile plains of the Eurasian frontier. Now bounded by seven nations, Poland has waxed and waned over the centuries,
- Poland China (breed of pig)
Poland China, breed of pig developed between 1835 and 1870 in Butler and Warren counties, Ohio, U.S., by a fusion of Polish pigs and Big Chinas. The Poland China is black with a white face and feet and a white tip on the tail; the ears droop. Ranking among the largest modern breeds, it is a popular
- Poland, Battle of (World War II)
World War II: The campaign in Poland, 1939: Against northern Poland, General Fedor von Bock commanded an army group comprising General Georg von Küchler’s 3rd Army, which struck southward from East Prussia, and General Günther von Kluge’s 4th Army, which struck eastward across the base of the Corridor. Much stronger in troops and in tanks,…
- Poland, Congress Kingdom of (historical state, Poland)
Congress Kingdom of Poland, Polish state created (May 3, 1815) by the Congress of Vienna as part of the political settlement at the end of the Napoleonic Wars. It was ruled by the tsars of Russia until its loss in World War I. The Kingdom of Poland comprised the bulk of the former Grand Duchy of
- Poland, flag of
horizontally divided white-red national flag. It has a width-to-length ratio of 5 to 8.The first recorded use of the coat of arms of Poland, a white eagle on a red shield, dates from the 13th century. The reason for the choice of colours is not known, but it may simply have been a desire to make a
- Poland, history of
history of Poland, a survey of important events and people in the history of Poland from the time of its foundation as a state. Located at a geographic crossroads in central Europe, Poland has waxed and waned over the centuries, buffeted by the forces of regional history. In the mid-1500s united
- Poland, Invasion of (World War II [1939])
Invasion of Poland, attack on Poland by Nazi Germany that marked the start of World War II. The invasion lasted from September 1 to October 5, 1939. As dawn broke on September 1, 1939, German forces launched a surprise attack on Poland. The attack was sounded with the predawn shelling, by the
- Poland, Orthodox Church of (Eastern Orthodoxy)
Orthodox Church of Poland, ecclesiastically independent member of the Eastern Orthodox communion, established in 1924 to accommodate the four million Orthodox Christians residing in the vast Ukrainian and Byelorussian territories acquired by Poland after World War I. As the new political situation
- Poland, Partitions of (Polish history)
Partitions of Poland, (1772, 1793, 1795), three territorial divisions of Poland, perpetrated by Russia, Prussia, and Austria, by which Poland’s size was progressively reduced until, after the final partition, the state of Poland ceased to exist. The First Partition occurred after Russia became
- Polanie (people)
Poland: The early state: Two tribes, the Polanie—based around the fortified settlement (castrum) of Gniezno—and the Wiślanie—who lived near Kraków—expanded to bring other tribes under their control.
- Połaniec, Manifesto of (Polish history)
Tadeusz Kościuszko: Campaigns in Poland: …peasant masses, he issued the Manifesto of Połaniec, on May 7, suspending serfdom and reducing in half the existing villein service. This met with some resistance of the nobility. Defeats forced Kościuszko to retreat to his last stronghold, Warsaw. The defense of this city, besieged by Prussian and Russian armies…
- Polanisia trachysperma (plant)
clammyweed, (Polanisia trachysperma), North American herb of the Cleome genus of the family Cleomaceae, closely related to the mustard family, Brassicaceae. The plant is 60 cm (2 feet) tall and has leaves that give off a foul odour when bruised. The stems and three-parted leaves are hairy and
- Polano, Pietro Soave (Italian theologian)
Paolo Sarpi was an Italian patriot, scholar, and state theologian during Venice’s struggle with Pope Paul V. Between 1610 and 1618 he wrote his History of the Council of Trent, an important work decrying papal absolutism. Among Italians, he was an early advocate of the separation of church and
- Polański, Rajmund Roman Thierry (Polish film director)
Roman Polanski is a French Polish director, scriptwriter, and actor who, through a variety of film genres, explored themes of isolation, desire, and absurdity. (Read Martin Scorsese’s Britannica essay on film preservation.) Shortly after the young Polanski’s family settled in Kraków, Poland, his
- Polanski, Roman (Polish film director)
Roman Polanski is a French Polish director, scriptwriter, and actor who, through a variety of film genres, explored themes of isolation, desire, and absurdity. (Read Martin Scorsese’s Britannica essay on film preservation.) Shortly after the young Polanski’s family settled in Kraków, Poland, his
- Polanski, Roman Raymond (Polish film director)
Roman Polanski is a French Polish director, scriptwriter, and actor who, through a variety of film genres, explored themes of isolation, desire, and absurdity. (Read Martin Scorsese’s Britannica essay on film preservation.) Shortly after the young Polanski’s family settled in Kraków, Poland, his
- Polanyi, John C. (Canadian chemist and educator)
John C. Polanyi is a chemist and educator who, with Dudley R. Herschbach and Yuan T. Lee, received the Nobel Prize for Chemistry in 1986 for his contribution to the field of chemical-reaction dynamics. Born to an expatriate Hungarian family, Polanyi was reared in England and attended Manchester
- Polanyi, John Charles (Canadian chemist and educator)
John C. Polanyi is a chemist and educator who, with Dudley R. Herschbach and Yuan T. Lee, received the Nobel Prize for Chemistry in 1986 for his contribution to the field of chemical-reaction dynamics. Born to an expatriate Hungarian family, Polanyi was reared in England and attended Manchester
- Polanyi, Karl (Hungarian politician)
Karl Polanyi was an economic anthropologist and former Hungarian political leader. In college in Budapest Polanyi founded the radical Club Galilei, which would have far-reaching effects on Hungarian intellectual life. He qualified as a lawyer in 1912 and served as a cavalry officer during World War
- Polanyi, Karl Paul (Hungarian politician)
Karl Polanyi was an economic anthropologist and former Hungarian political leader. In college in Budapest Polanyi founded the radical Club Galilei, which would have far-reaching effects on Hungarian intellectual life. He qualified as a lawyer in 1912 and served as a cavalry officer during World War
- Polanyi, Michael (Hungarian-British philosopher and scientist)
emergence: …theory of personal knowledge of Michael Polanyi, a Hungarian scientist and philosopher, with its levels of being and of knowing, none of which are wholly intelligible to those they describe.
- polar (dog)
spitz, any of a group of northern dogs—such as the chow chow, Pomeranian, and Samoyed—characterized by dense, long coats, erect pointed ears, and tails that curve over their backs. In the United States the name spitz is often given to any small, white, long-haired dog. It is also used for the
- polar air mass (meteorology)
polar air mass, air mass that forms over land or water in the higher latitudes. See air mass;
- polar anticyclone (meteorology)
polar anticyclone, wind system associated with a region in which high atmospheric pressure develops over or in the vicinity of the poles. The polar anticyclone is strongest in the cold season of the year. The Siberian anticyclone is an example of a polar anticyclone, as is the high-pressure area
- polar axis (astronomy)
telescope: Light gathering and resolution: In the equatorial mounting, the polar axis of the telescope is constructed parallel to Earth’s axis. The polar axis supports the declination axis of the instrument. Declination is measured on the celestial sky north or south from the celestial equator. The declination axis makes it possible for the telescope to…
- polar barren (ecosystem)
polar ecosystem: …in polar regions such as polar barrens and tundra.
- polar bear (mammal)
polar bear, (Ursus maritimus), great white northern bear (family Ursidae) found throughout the Arctic region. The polar bear travels long distances over vast desolate expanses, generally on drifting oceanic ice floes, searching for seals, its primary prey. The polar bear is the largest and most
- Polar Bear Pass National Wildlife Area (wildlife area, Canada)
Bathurst Island: Polar Bear Pass National Wildlife Area (1990), which extends through the centre of the island, has been the site of a wildlife research station since 1968. Discovered in 1819 by the British explorer Sir William Parry, the island was named for Henry Bathurst, the 3rd…
- Polar Bear Provincial Park (park, Ontario, Canada)
Polar Bear Provincial Park, wilderness park, northern Ontario, Canada, on Hudson and James bays. A huge undeveloped area of 9,300 square miles (24,087 square km), it is the largest of Ontario’s provincial parks; it was established in 1970. Polar Bear Provincial Park is accessible only by plane or
- polar biome
polar ecosystem, complex of living organisms in polar regions such as polar barrens and tundra. Polar barrens and tundra are found at high latitudes on land surfaces not covered by perpetual ice and snow. These areas lying beyond the tree line comprise more than 10 percent of the Earth’s land
- polar body (cell)
oogenesis: …cell is known as a polar body. The secondary ovum grows in the ovary until it reaches maturation; it then breaks loose and is carried into the fallopian tubes. Once in the fallopian tubes, the secondary egg cell is suitable for fertilization by the male sperm cells. See also ovulation;…
- polar bond (chemistry)
ionic bond, type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound. Such a bond forms when the valence (outermost) electrons of one atom are transferred permanently to another atom. The atom that loses the electrons becomes a positively
- polar cap (geography)
Mars: Polar regions: For telescopic observers the most striking regular changes on Mars occur at the poles. With the onset of fall in a particular hemisphere, clouds develop over the relevant polar region, and the cap, made of frozen carbon dioxide, begins to grow. The smaller…
- polar climate (climatology)
snow and ice climate, major climate type of the Köppen classification characterized by bitterly cold temperatures and scant precipitation. It occurs poleward of 65° N and S latitude over the ice caps of Greenland and Antarctica and over the permanently frozen portion of the Arctic Ocean. It is
- Polar continental (meteorology)
polar air mass, air mass that forms over land or water in the higher latitudes. See air mass;
- Polar continental air mass (meteorology)
polar air mass, air mass that forms over land or water in the higher latitudes. See air mass;
- polar coordinates (mathematics)
polar coordinates, system of locating points in a plane with reference to a fixed point O (the origin) and a ray from the origin usually chosen to be the positive x-axis. The coordinates are written (r,θ), in which ris the distance from the origin to any desired point P and θis the angle made by
- polar cusp (astronomy)
geomagnetic field: Outer magnetic field: …field lines split are called polar cusps. The projection of the polar cusps on the atmosphere at about 72° magnetic latitude creates the dayside auroral ovals. Auroras can be seen in these regions in the dark hours of winter, but they are much weaker than on the nightside because the…
- polar cyclone (meteorology)
polar vortex, large area of persistent low pressure generally located above each of Earth’s polar regions and containing a mass of extremely cold air. The altitude of this cyclone extends from the middle of the troposphere (the lowest level of Earth’s atmosphere, which spans the region from the
- polar desert (ecosystem)
polar ecosystem: Biota of the Arctic: The true polar desert generally occurs on coastal areas fringing the Arctic Ocean and on areas of a few hundred metres elevation in the extreme High Arctic where soils have not developed and the frost-free period and soil moisture are insufficient for most plant growth. The occasional…
- polar easterlies (meteorology)
atmospheric circulation: …and equatorward as the polar easterlies. In the northern polar regions, where water and land are interspersed, the polar easterlies give way in summer to variable winds.
- polar ecosystem
polar ecosystem, complex of living organisms in polar regions such as polar barrens and tundra. Polar barrens and tundra are found at high latitudes on land surfaces not covered by perpetual ice and snow. These areas lying beyond the tree line comprise more than 10 percent of the Earth’s land
- polar effect (chemistry)
carboxylic acid: Acidity: …one example of the so-called inductive effect, in which a substituent affects a compound’s distribution of electrons. There are a number of such effects, and atoms or groups may be electron-withdrawing or electron-donating as compared with hydrogen. The presence of such groups near the COOH group of a carboxylic acid…
- Polar Express, The (film by Zemeckis [2004])
the Andrews Sisters: … (1987), Jakob the Liar (1999), The Polar Express (2004), and The Chronicles of Narnia (2005).
- Polar Express, The (book by Van Allsburg)
Chris Van Allsburg: The Polar Express (1985) earned Van Allsburg another Caldecott Medal. The tale of a boy’s magical train ride to the North Pole on Christmas Eve, brought to life by Van Allsburg’s dreamlike illustrations in hues of blue and purple, ranks among the best-selling children’s books…
- polar flattening (geodesy)
geoid: Flattening (f) is defined as the difference in magnitude between the semimajor axis (a) and the semiminor axis (b) divided by the semimajor axis, or f = (a − b)/a. For Earth the semimajor axis and semiminor axis differ by about 21 kilometres (13 miles),…
- polar fox (mammal)
Arctic fox, (Vulpes lagopus), northern fox of the family Canidae, found throughout the Arctic region, usually on tundra or mountains near the sea. Fully grown adults reach about 50–60 cm (20–24 inches) in length, exclusive of the 30-cm (12-inch) tail, and a weight of about 3–8 kg (6.6–17 pounds).
- polar front (meteorology)
polar front, in meteorology, the transition region separating warmer tropical air from colder polar air in the mid-latitudes. This region possesses a strong temperature gradient, and thus it is a reservoir of potential energy that can be readily tapped and converted into the kinetic energy
- polar front jet (meteorology)
polar front jet stream, a belt of powerful upper-level winds that sits atop the polar front. The winds are strongest in the tropopause, which is the upper boundary of the troposphere, and move in a generally westerly direction in midlatitudes. The vertical wind shear which extends below the core of
- polar front jet stream (meteorology)
polar front jet stream, a belt of powerful upper-level winds that sits atop the polar front. The winds are strongest in the tropopause, which is the upper boundary of the troposphere, and move in a generally westerly direction in midlatitudes. The vertical wind shear which extends below the core of
- polar glacier
glacier: Mass balance: A polar glacier is defined as one that is below the freezing temperature throughout its mass for the entire year; a subpolar (or polythermal) glacier contains ice below the freezing temperature, except for surface melting in the summer and a basal layer of temperate ice; and…
- polar low (meteorology)
polar vortex, large area of persistent low pressure generally located above each of Earth’s polar regions and containing a mass of extremely cold air. The altitude of this cyclone extends from the middle of the troposphere (the lowest level of Earth’s atmosphere, which spans the region from the
- Polar Medal (exploration award)
Sir Ranulph Fiennes: … (OBE) in 1993 and the Polar Medal in 1984 (recognized again in 1995 for his work in both polar regions). Many of the endeavours undertaken by Fiennes were fund-raisers, and over the years he raised millions for a variety of charities.
- polar motion (geophysics)
polar motion, a periodic rotation of the Earth’s spin axis about a mean axis, somewhat like the wobble of a spinning top. Slight variations in latitude and longitude result from this wobble because the poles are displaced from their mean positions. The north pole of rotation rotates
- polar nuclei (plant anatomy)
plant reproductive system: Angiosperms: …with the two nuclei (polar nuclei) within the large central cell of the female gametophyte. The resultant nucleus, which has three sets of chromosomes, is the primary endosperm nucleus. This process, double fertilization, occurs only in angiosperms.
- polar nucleus (plant anatomy)
plant reproductive system: Angiosperms: …with the two nuclei (polar nuclei) within the large central cell of the female gametophyte. The resultant nucleus, which has three sets of chromosomes, is the primary endosperm nucleus. This process, double fertilization, occurs only in angiosperms.
- polar orbit
spaceflight: Earth orbit: …to be put into a polar orbit—an orbit that crosses over Earth’s poles—it is launched in a northerly or southerly direction. Although the benefit of an easterly launch is lost, a spacecraft in an orbit perpendicular to the Equator offers other advantages. As Earth turns on its axis, the spacecraft…
- polar Pacific air mass (meteorology)
North America: Air masses: …maritime tropical, and the maritime polar Pacific are the most influential air masses. Polar continental air reflects the spread of a negative temperature anomaly over much of the continent. It is a dry, cool-to-cold mass of stable air forming under an immense dome of high pressure above the Canadian Shield,…
- polar projection (cartography)
map: Map projections: The polar projection is an azimuthal projection drawn to show Arctic and Antarctic areas. It is based on a plane perpendicular to the Earth’s axis in contact with the North or South Pole. It is limited to 10 or 15 degrees from the poles. Parallels of…
- polar region (geography)
polar region, area around the North Pole or the South Pole. The northern polar region consists mainly of floating and pack ice, 7–10 feet (2–3 m) thick, floating on the Arctic Ocean and surrounded by land masses. The ice cap of the southern polar region averages 6,700 feet (about 2,000 m) in
- Polar Satellite Launch Vehicle (Indian launch vehicle)
Chandrayaan: A Polar Satellite Launch Vehicle launched the 590-kg (1,300-pound) Chandrayaan-1 on October 22, 2008, from the Satish Dhawan Space Centre on Sriharikota Island, Andhra Pradesh state. The probe then was boosted into an elliptical polar orbit around the Moon, 504 km (312 miles) high at its…
- polar stratospheric cloud (atmosphere)
ozone depletion: Antarctic ozone hole: …on particles that make up polar stratospheric clouds (PSCs) in the lower stratosphere.
- Polar Urals (mountain range, Russia)
Ural Mountains: Physiography: The northernmost Polar Urals extend some 240 miles (400 km) from Mount Konstantinov Kamen in the northeast to the Khulga River in the southeast; most mountains rise to 3,300–3,600 feet (1,000–1,100 metres) above sea level, although the highest peak, Mount Payer, reaches 4,829 feet (1,472 metres). The…
- polar vortex (meteorology)
polar vortex, large area of persistent low pressure generally located above each of Earth’s polar regions and containing a mass of extremely cold air. The altitude of this cyclone extends from the middle of the troposphere (the lowest level of Earth’s atmosphere, which spans the region from the
- polar wandering (geophysics)
polar wandering, the migration of the magnetic poles over Earth’s surface through geologic time. The study of polar wandering began in the early 20th century with Austrian priest and geologist Damian Kreichgauer and German scientists Wladimir Köppen and Alfred Wegener, who proposed the first paths