Natalia Grossman is a multidiscipline sport climber who is considered one of the leading competitors in bouldering. A standout from an early age, Grossman won her first world championship in 2021 at age 20. She also has excelled in lead climbing and competes in combined and speed events. Grossman

George Grossmith was an English comedian and singer who created many of the chief characters in the original productions of Gilbert and Sullivan light operas. After several years of journalistic work, Grossmith began about 1870 as a public entertainer, with songs, recitations, and sketches. His

George Grossmith: Both of his sons, George (1874–1935) and Lawrence Grossmith (1877–1944), were distinguished actors. George, Jr., became a well-known figure in musical comedies, entered the motion-picture industry in 1932, and wrote musical plays.

George Grossmith: … (1888), and, with his brother Weedon Grossmith (1852–1919), an actor and playwright, wrote the amusing Diary of a Nobody (1892). His humorous songs and sketches exceeded 600. Both of his sons, George (1874–1935) and Lawrence Grossmith (1877–1944), were distinguished actors. George, Jr., became a well-known figure in musical comedies, entered…

Zürich: The contemporary city: …architectural legacy including the Romanesque Grossmünster, built by Charlemagne in the 700s; the 13th-century St. Peter’s Church; and elegant guild houses and patrician residences, some of which are used as restaurants or for civic functions. The Fraumünster (Minster of Our Lady) is noted for its stained glass windows designed by…

Enrico Dandolo: …a silver coin called the grosso, or matapan. This began a wide-ranging economic policy intended to promote trade with the East. Dandolo’s image appears on the grosso coin; he is wearing a cloak and holding the “ducal promise” in his left hand while St. Mark presents him with the gonfalon…

metalwork: Italy: …famous was the late-15th-century craftsman Niccolo Grosso of Florence, nicknamed “Il Caparra” because he gave no credit but insisted on money on account. From his hand is the well-known lantern on the Palazzo Strozzi in Florence, repeated with variations elsewhere in the same city. Siena has lanterns and banner holders…

grossular, a calcium aluminum garnet that sometimes resembles the gooseberry fruit. It can be colourless (when pure), white, yellow, brown, red, or green. Massive greenish grossular, though only superficially resembling jade, is sometimes marketed under the name South African, or Transvaal, jade in

gooseberry: Major species: …common commercial fruits are the English gooseberries (Ribes uva-crispa), popularly called grossularia, which are native to the Old World and have long been cultivated. In Europe the large-fruited cultivated gooseberries became naturalized. Grossularia do not prosper in the United States, because they are susceptible to mildews and rusts. Because they…

gooseberry, any of several species of flowering shrubs of the genus Ribes (family Grossulariaceae), cultivated for their edible fruits and as ornamentals. Currants and gooseberries form two groups within the genus Ribes; some taxonomic systems formerly placed gooseberries in their own genus,

ribes: the gooseberries, constituting the family Grossulariaceae. They are native to the temperate regions of the Northern Hemisphere, extending southward in the Americas into the Andes. Some authorities formerly separated the gooseberries as the genus Grossularia. The tart fruits of both groups are used in cooking and baking, and several species…

grossular, a calcium aluminum garnet that sometimes resembles the gooseberry fruit. It can be colourless (when pure), white, yellow, brown, red, or green. Massive greenish grossular, though only superficially resembling jade, is sometimes marketed under the name South African, or Transvaal, jade in

coin: Germany and central Europe: …gold and multiplied the silver grossus already issued by Cologne under Henry VII (1308–13). Louis reduced the number of purely imperial mints. Many others operated by rights granted to the nobility, the churches, and certain municipalities, and from these henceforth appeared the bulk of German coinage, including from 1520 the…

Oradea, city, capital of Bihor judeƫ (county), northwestern Romania. It lies about 8 miles (13 km) east of the Hungarian border, along the Crişul Repede River where it leaves the western foothills of the Western Carpathians and flows onto the Hungarian Plain. One of the first feudal states in the

Gilbert H. Grosvenor was an American geographer, writer, and long-time editor of the National Geographic Magazine and president of the National Geographic Society. A graduate of Amherst College, Grosvenor was hired by the president of the National Geographic Society, the inventor Alexander Graham

Gilbert H. Grosvenor was an American geographer, writer, and long-time editor of the National Geographic Magazine and president of the National Geographic Society. A graduate of Amherst College, Grosvenor was hired by the president of the National Geographic Society, the inventor Alexander Graham

George Grosz was a German artist whose caricatures and paintings provided some of the most vitriolic social criticism of his time. After studying art in Dresden and Berlin from 1909 to 1912, Grosz sold caricatures to magazines and spent time in Paris during 1913. When World War I broke out, he

Brussels: City layout: …medieval marketplace known as the Grand’ Place (Flemish: Grote Markt), the city’s premier architectural tourist attraction. This square, with its elaborately decorated 17th-century guildhalls, lies at the heart of the Old Town. It is occupied on its south side by the imposing Town Hall (French: Hôtel de Ville; Flemish: Stadhuis)…

Winkler Prins Encyclopedie, the standard Dutch encyclopaedia, published by Elsevier in Amsterdam. The first edition (1870–82) was based on the German Brockhaus Enzyklopädie (q.v.). The 6th edition (1947–54) appeared in 18 volumes. A new, 25-volume, thoroughly revised edition was published in

George Grote was an English historian, noted for his works on ancient Greece. At the age of 16 Grote joined his father’s bank in London and worked in it until 1843, using his spare time to perfect his command of Greek and to learn German, economics, and philosophy. From 1832 to 1841 he was a member

Georg Friedrich Grotefend was a German teacher and language scholar who made the first major breakthrough in the decipherment of ancient Persian cuneiform script. When Grotefend began teaching at the Göttingen city school in 1797, Europe was already familiar with the wedge-shaped cuneiform writing

Hannah Höch: In the colour assemblage Grotesque (1963), for example, two pairs of women’s legs are posed on a cobblestone street; one pair supports a woman’s fragmented facial features, the other a man’s bespectacled eyes and wrinkled forehead.

comedy: Comedy, satire, and romance: …in the direction of the grotesque, which implies an admixture of elements that do not match. The ironic gaze eventually penetrates to a vision of the grotesque quality of experience, marked by the discontinuity of word and deed and the total lack of coherence between appearance and reality. This suggests…

grotesque, in architecture and decorative art, fanciful mural or sculptural decoration involving mixed animal, human, and plant forms. The word is derived from the Italian grotteschi, referring to the grottoes in which these decorations were found c. 1500 during the excavation of Roman houses such

tapestry: 16th century: …Bachiacca (1494–1557), who designed the Grotesques (c. 1550), one of the most famous and influential tapestry sets produced by the Arrazeria Medicea.

Germany: Formation of the German Democratic Republic: …installed the former Social Democrat Otto Grotewohl as premier at the head of a cabinet that was nominally responsible to the chamber. Although the German Democratic Republic was constitutionally a parliamentary democracy, decisive power actually lay with the SED and its boss, the veteran communist functionary Walter Ulbricht, who held…

Klaus Groth was a German regional poet whose book Quickborn (1853) first revealed the poetic possibilities of Plattdeutsch (Low German). Groth was originally a schoolteacher, but his tireless self-education finally enabled him to win a chair at Kiel University (1866). Inspired by the Scots dialect

Alexandre Grothendieck was a German French mathematician who was awarded the Fields Medal in 1966 for his work in algebraic geometry. After studies at the University of Montpellier (France) and a year at the École Normale Supérieure in Paris, Grothendieck received his doctorate from the University

Hugo Grotius was a Dutch jurist and scholar whose masterpiece De Jure Belli ac Pacis (1625; On the Law of War and Peace) is considered one of the greatest contributions to the development of international law. Also a statesman and diplomat, Grotius has been called the “father of international law.”

Groton, city and town (township), New London county, southeastern Connecticut, U.S., on the east bank of the Thames River, opposite New London. In 1649 a trading post was established in the area (then part of New London) by Jonathan Brewster, son of William, leader of the Plymouth colony. The

Groton, town (township), Middlesex county, Massachusetts, U.S. It is located on the Nashua and Squannacook rivers, about 35 miles (56 km) northwest of Boston. Settled and incorporated in 1655, it was probably named for the ancestral home of Massachusetts Bay Colony Governor John Winthrop in

Groton: Groton School was founded in 1884 by the Reverend Endicott Peabody as a privately endowed boarding school (grades 8–12) for boys. In addition to a standard academic program, Peabody’s original curriculum included subjects that were not commonly offered at preparatory schools of the day, such…

Jerzy Grotowski was an international leader of the experimental theatre who became famous in the 1960s as the director of productions staged by the Polish Laboratory Theatre of Wrocław. A leading exponent of audience involvement, he set up emotional confrontations between a limited group of

eclipse: Temperature of the corona: About 1930 German astronomer Walter Grotrian examined spectra of the solar corona he had obtained at a total eclipse. He noticed that, although coronal light had the same distribution of colours as light from the solar surface—the photosphere—it lacked the absorption lines observed in photospheric light. Grotrian hypothesized that…

Basilian: …in the Byzantine Rite: (1) Grottaferrata in the Italo-Albanian Rite was restored in 1880 in its Greek traditions and controls monasteries in southern Italy and Sicily. Grottaferrata was once famous for creating religious art and illumination and for copying manuscripts. (2) St. Josaphat in the Ukrainian and Romanian Rite was…

Grottaglie, town, Puglia (Apulia) region, southern Italy. The town’s castle dates from the 14th century; the church of the Matrice has a facade of the same period and a 16th-century stone relief of the Annunciation. Its chief industry is pottery manufacture, and there is a school of ceramics.

Lascaux, cave containing one of the most outstanding displays of prehistoric art yet discovered. Located above the Vézère River valley near Montignac, in Dordogne, France, the cave is a short distance upstream from the Eyzies-de-Tayac series of caves. Lascaux, together with some two dozen other

grotesque: …is derived from the Italian grotteschi, referring to the grottoes in which these decorations were found c. 1500 during the excavation of Roman houses such as the Golden House of Nero. Grotesque decoration was common on 17th-century English and American case furniture.

photochemical reaction: History: …of absorbing optical radiation (the Grotthus-Draper law). German chemist Robert Bunsen and English chemist Henry Roscoe demonstrated in 1859 that the amount of fluorescence or phosphorescence was determined by the total amount of optical radiation absorbed and not the energy content (i.e., the wavelength, colour, or frequency) of the radiation.…

grotto, natural or artificial cave used as a decorative feature in 18th-century European gardens. Grottoes derived from natural caves were regarded in antiquity as dwelling places of divinities. Grottoes were often constructed from a fanciful arrangement of rocks, shells, bones, broken glass, and

Portland: The contemporary city: The Grotto is a Roman Catholic shrine of gardens and religious statues. Seventeen bridges cross the city’s waterways. Portland is the home of the National Basketball Association’s Trail Blazers. Educational institutions include the University of Portland (1901), Concordia University (1905), Reed College (1908), Lewis and…

Olympic Games: Lake Placid, New York, U.S., 1932: …final Olympic appearance of Norwegian Johan Gröttumsbråten, who helped his country capture all three medals in the Nordic combined event for the third consecutive Winter Olympics. In figure skating three-time champion Gillis Grafström (Sweden) was dethroned by Austrian Karl Schäfer.

Battle of Waterloo: The Battles of Quatre-Bras and Ligny: …midday on the 17th, Marshal Emmanuel de Grouchy with 33,000 men—nearly one-third of Napoleon’s total strength of 105,000—began a dilatory pursuit of Blücher that would effectively remove his force from the action to come. On the left, Ney did nothing to hinder Wellington’s orderly withdrawal from Quatre-Bras, and the eventual…

Lionel-Adolphe Groulx was a Canadian priest and historian who for 50 years strongly influenced the Quebec nationalist movement. The son of a lumberjack, Groulx became a seminarian at Sainte-Thérèse-de-Blaineville and Montreal and was ordained a Roman Catholic priest in 1903. After teaching at a

drawing: Surfaces: …by far the most popular ground.

heraldry: The field: In a blazon (verbal description) of the arms, their field, or background layer, appears first. It may be one of the metals or (gold) or argent (silver), one of the colours gules (red), azure (blue), vert (green), purpure (purple), or sable (black), or one…

ground, in electricity, electrical contact with the Earth, which remains essentially at a constant potential. A grounded wire on a lightning rod leads large electric charges from the atmosphere directly to Earth, preventing them from taking other paths that might result in damage to property or

attack aircraft, type of military aircraft that supports ground troops by making strafing and low-level bombing attacks on enemy ground forces, tanks and other armored vehicles, and installations. Attack aircraft are typically slower and less maneuverable than air combat fighters but carry a large

baseball: Getting on base: …hit high into the air), ground balls (balls hit at a downward angle into the ground), and line drives (a ball that is close to and parallel to the ground). Another way the batter can reach base is through an error. An error occurs when a mistake by the fielder…

ground bass, in music, a short, recurring melodic pattern in the bass part of a composition that serves as the principal structural element. Prototypical instances are found in 13th-century French vocal motets as well as in 15th-century European dances, where a recurrent melody served as a cantus

hamburger: …“hamburger,” “chopped beef,” or “ground beef.” It must be ground from fresh beef with no by-products or nonmeat extenders, but the USDA does permit the inclusion of loose beef fat and seasonings in meat labeled “hamburger.” Also, by law, hamburger and chopped or ground beef sold commercially may contain…

ground beetle, (family Carabidae), any member of more than 40,000 insect species in one of the largest families in the insect order Coleoptera. They can be found in almost any terrestrial habitat on Earth. Ground beetles are recognized by their long legs and shiny black or brown elytra (wing

Salman Rushdie: Post-fatwa writings: …life, Rushdie published the novels The Ground Beneath Her Feet (1999) and Fury (2001). Step Across This Line, a collection of essays he wrote between 1992 and 2002 on subjects ranging from the September 11 attacks to The Wizard of Oz, was issued in 2002.

blizzard: A ground blizzard occurs when there is no falling snow, but snow is drifting and blowing near the ground.

African music: Musical bows: …of the zither, the so-called ground bow or earth bow of equatorial Africa, which has one end planted in the ground, qualifies as a ground harp.

club moss: Major genera and species: Ground cedar (D. digitatum), native to northern North America, produces fanlike branches resembling juniper branchlets.

ground cherry, (genus Physalis), genus of some 80 species of small herbaceous plants in the nightshade family (Solanaceae), the majority of which are native to the New World. The berries of some ground cherry species are edible, and several species are commercially important as food crops,

airport: Air traffic control: …on ground maneuvers by the ground controller, whose responsibility is to avoid conflicting movements of aircraft in the operational area of the airfield. The ground controller gives the pilot instructions on reaching the apron stand position via the appropriate turnoffs and taxiways. Final positioning may be the responsibility of an…

permafrost: Effects of solar radiation, vegetation, and snow cover: The main role of vegetation in permafrost areas is to shield perennially frozen ground from solar energy. Vegetation is an excellent insulating medium and removal or disturbance of it, either by natural processes or by humans, causes thawing of the underlying permafrost. In the continuous zone the permafrost table…

cricket: Ground crickets (subfamily Nemobiinae, or sometimes Gryllinae), approximately 12 mm long, are commonly found in pastures and wooded areas. Their song is a series of soft, high-pitched trills. The striped ground cricket (Nemobius vittatus) has three dark stripes on its abdomen.

ground cuckoo, any of about 15 species of birds constituting the subfamily Neomorphinae of the cuckoo family (Cuculidae), noted for terrestrial habits. Of the 11 New World species, three, the striped cuckoo (Tapera naevia), the pheasant cuckoo (Dromococcyx phasianellus), and the pavonine cuckoo (D.

percussion instrument: Membranophones: …a small group composed of ground drums and pot drums can also be distinguished. Ground drums, consisting in their simplest form of an animal skin stretched over the opening of a pit, are found in many parts of the world. The skin may also be held taut by several players,…

game: …or partridge, and pheasant; and ground game, such as the squirrel, hare, and rabbit; (3) big game, predominantly venison, including roebuck, deer, elk, moose, and caribou but also including other large animals such as bear and wild boar.

fur: …elements: a dense undercoat, called ground hair, and longer hairs, extending beyond that layer, called guard hair. The principal function of ground hair is to maintain the animal’s body temperature; that of guard hair is to protect the underlying fur and skin and to shed rain or snow. Pelts that…

American yew, (Taxus canadensis), a prostrate, straggling evergreen shrub of the family Taxaceae, found in northeastern North America. American yew also is a lumber trade name for the Pacific yew. The American yew, the hardiest of the yew species, provides excellent ground cover in forested areas.

coraciiform: Locomotion and feeding: The ground hornbills (Bucorvus species) exhibit a definite social organization when foraging. Three or four members of a group searching for insects and other small animals on the ground may keep near each other, with the result that prey frightened into activity by one bird may…

permafrost, perennially frozen ground, a naturally occurring material with a temperature colder than 0 °C (32 °F) continuously for two or more years. Such a layer of frozen ground is designated exclusively on the basis of temperature. Part or all of its moisture may be unfrozen, depending on the

temperature inversion: A ground inversion develops when air is cooled by contact with a colder surface until it becomes cooler than the overlying atmosphere; this occurs most often on clear nights, when the ground cools off rapidly by radiation. If the temperature of surface air drops below its…

trailing arbutus, (Epigaea repens), trailing plant of the heath family (Ericaceae), native to sandy or boggy, acid woodlands of eastern North America. It has oblong, hairy evergreen leaves 2–6 cm (0.75–2.5 inches) long. The highly fragrant white, pink, or rosy flowers have a five-lobed corolla (the

meristem: …will become the epidermis; the ground meristem, which will form the ground tissues comprising parenchyma, collenchyma, and sclerenchyma cells; and the procambium, which will become the vascular tissues (xylem and phloem).

moraine: A ground moraine consists of an irregular blanket of till deposited under a glacier. Composed mainly of clay and sand, it is the most widespread deposit of continental glaciers. Although seldom more than 5 metres (15 feet) thick, it may attain a thickness of 20 m.

Christianity: The belief in the oneness of the Father and the Son: …the impersonal concept of “the Ground of Being,” or “Being Itself,” pointed toward an understanding of the pre-personal depths of the transcendence of Godhood.

parrot: Equally unusual is the ground parrot, or ground parakeet (Pezoporus wallicus). Rare local populations exist in the wastelands of coastal southern Australia and western Tasmania. It runs in the grass, flushes like a quail, and makes a sudden deceptive pitch, and it was formerly hunted with dogs. It eats…

parrot: Equally unusual is the ground parrot, or ground parakeet (Pezoporus wallicus). Rare local populations exist in the wastelands of coastal southern Australia and western Tasmania. It runs in the grass, flushes like a quail, and makes a sudden deceptive pitch, and it was formerly hunted with dogs. It eats…

ground pearl, (genus Margarodes), any of a group of scale insects in the family Margarodidae (order Homoptera) that have an iridescent globular body 2 to 4 mm (0.08 to 0.16 inch) in length. Ground pearl insects vary in colour from metallic bronze, red, or gold to cream or silver. They are worldwide

club moss: Major genera and species: Ground pine (Dendrolycopodium obscurum), a 25-cm- (10-inch-) tall plant, has underground-running stems. It is native to moist woods and bog margins in northern North America, to mountain areas farther south, and to eastern Asia.

bugleweed: Ground pine, or yellow bugle (A. chamaepitys), is shorter and has yellow flowers and three-parted needlelike leaves that are pine-scented.

club moss, (family Lycopodiaceae), any of some 400 species of seedless vascular plants constituting the only family of the lycophyte order Lycopodiales. The taxonomy of the family has been contentious, and the number of genera vary depending on the source. The plants are native mainly to tropical

celestial navigation: This location is called the ground position (GP). GP can thus be stated in terms of celestial coordinates, with the declination of the celestial object equal to latitude and the Greenwich hour angle equal to longitude. Almanacs such as those published by the Nautical Almanac Office of the U.S. Naval…

telecommunications media: Reflected propagation: …of reflected wave propagation are ground reflection, where the wave is reflected off land or water, and ionospheric reflection, where the wave is reflected off an upper layer of the Earth’s ionosphere (as in shortwave radio; see below The radio-frequency spectrum: HF).

ground roller, any of five species of pigeon-sized birds that comprise the family Brachypteracidae (order Coraciiformes) known for their tumbling flight. They are found only in Madagascar. Four species inhabit deep forest; one, the long-tailed ground roller (Uratelornis chimaera), confined to a

bull shark, (Carcharhinus leucas), species of large predatory shark found in shallow coastal lagoons, estuaries, and harbours in tropical and subtropical oceans and seas worldwide. The bull shark is one of only a few shark species also capable of living and breeding in freshwater environments. Bull

carcharhinid, any member of the shark family Carcharhinidae, which includes 12 genera and about 50 species found worldwide. Carcharhinids are found primarily in warm and temperate ocean waters, though a few species inhabit fresh or brackish water. The Carcharhinidae is one of the largest families

sloth: Classification and paleontology: …Megalonychidae, whose extinct relatives, the ground sloths, once ranged into areas of North America as far north as Alaska and southern Canada. Different species of ground sloths varied greatly in size. Most were small, but one, the giant ground sloth (Megatherium americanum), was the size of an elephant; others were…

mining: Mechanized methods: Ground sluicing is a special technique for the mining of natural placers as well as artificial ones (tailings piles, for example). A natural flow of water is used to disintegrate and then transport the material through a sluice, where the valuable mineral is concentrated. In…

wolf spider, (family Lycosidae), any member of the spider family Lycosidae (order Araneida), a large and widespread group made up of more than 2,300 species worldwide. They are named for the wolflike habit of chasing and pouncing upon prey. About 240 species occur in North America and about 50 in

ground squirrel, any of 62 species of long-bodied terrestrial rodents that are active during the day and have short legs, strong claws, small rounded ears, and a short or moderately long tail. Colour varies widely among species from gray, tawny, or pale brown to olive, reddish, or very dark brown.

spectroscopy: Basic properties of atoms: …possible energy state (called the ground state) can be excited to a higher state only if energy is added by an amount that is equal to the difference between the two levels. Thus, by measuring the energy of the radiation that has been absorbed by the atom, the difference in…

tennis: Strategy and technique: …players whose strength is their ground stroke, the priority is to maneuver the opponent into a vulnerable position for a winning passing shot, placement, or drive that forces an error. All shots after the serve—volley or ground stroke—can be played on either the forehand (where, if the racket were viewed…

ground substance, an amorphous gel-like substance present in the composition of the various connective tissues. It is most clearly seen in cartilage, in the vitreous humour of the eye, and in the Wharton’s jelly of the umbilical cord. It is transparent or translucent and viscous in composition; the

Sweden: Political stagnation (1866–1900): …demand for an abolition of ground tax, which had been levied from ancient times, and the defense question, where the demand was for an abolition of the military system of indelningsverket—i.e., an army organization in which the soldiers were given small holdings to live on. The defense system was to…

ground thrush, any of about 37 species of thrushes of the genus Zoothera (family Turdidae), including birds sometimes placed in the genera Geokichla, Ixoreus, Oreocincla, and Ridgwayia and some that have been assigned to Turdus. All are more than 20 centimetres (8 inches) long and have pale

angiosperm: Ground tissue: The ground tissue system arises from a ground tissue meristem and consists of three simple tissues: parenchyma, collenchyma, and sclerenchyma (Figure 5). The cells of each simple tissue bear the same name as their respective tissue.

hand tool: Neolithic tools: A ground tool is one that was chipped to rough shape in the old manner and then rubbed on or with a coarse abrasive rock to remove the chip scars either from the entire surface or around the working edge. Polishing was a last step, a…

airport: Links to local ground transportation: An airport should always be considered an interchange where different modes of transportation connect. Since the airport itself is not a primary destination, consideration must be given to access by surface vehicles. This is as critical a factor in airport layout and design…

Uta: The common side-blotched lizard, or ground uta (Uta stansburiana), is widespread in the western United States. Uta species range in length from 10 to 27 cm (4 to 11 inches). They are usually dull-coloured; the males of some species have a blue throat and abdomen. These lizards…

electromagnetic radiation: Radio waves: …further facilitated by the so-called ground wave. This form of electromagnetic wave closely follows Earth’s surface, particularly over water, as a result of the wave’s interaction with the terrestrial surface. The range of the ground wave (up to 1,600 km [1,000 miles]) and the bending and reflection of the sky…

World Trade Center, complex of several buildings around a central plaza in New York City that in 2001 was the site of the deadliest terrorist attack in American history. (See September 11 attacks.) The complex—located at the southwestern tip of Manhattan, near the shore of the Hudson River and a

tunnels and underground excavations: Ground support: …of the opening, termed the ground-arch effect. At the heading the effect is three-dimensional, locally creating a ground dome in which the load is arched not only to the sides but also forward and back. If permanence of the ground arch is completely assured, stand-up time is infinite, and no…

history of flight: Avionics, passenger support, and safety: The ground-controlled approach (GCA), in which a ground observer monitors the course and descent angle of an aircraft via radar, enables pilots to land under extremely adverse weather conditions. GCA was used extensively by the U.S. military during the 1948 Berlin blockade and airlift and was…