Names and etymology.

The word "Diospyros" comes from the ancient Greek words "dios" ("δῐος") and "pyron" ("πῡρον"). A popular etymology construed this as "divine fruit", or as meaning "wheat of Zeus" or "God's pear" and "Jove's fire". The dio-, as shown by the short vowel 'i', has nothing to do with 'divine' (δῑoς ), "dio-" being an affix attached to plant names, and in classical Greek the compound referred to "the fruit of the nettle tree".  The word "persimmon" itself is derived from "putchamin", "pasiminan", or "pessamin", from Powhatan, an Algonquian language of the eastern United States, meaning "a dry fruit".

Description.

The tree "Diospyros kaki" is the most widely cultivated species of persimmon. Typically the tree reaches in height and is round-topped. It usually stands erect, but sometimes can be crooked or have a willowy appearance.  The leaves are long, and are oblong in shape with brown-hairy petioles in length. They are leathery and glossy on the upper surface, brown and silky underneath. The leaves are deciduous and bluish-green in color. In the fall, they turn to yellow, orange, or red.  Persimmon trees are typically dioecious, meaning male and female flowers are produced on separate trees. Some trees have both male and female flowers and in rare cases also bear the 'perfect' flower. Male flowers are pink and appear in groups of 3. They have a 4-parted calyx, a corolla, and 24 stamens in 2 rows. Female flowers are creamy-white and appear singly. They have a large calyx, a 4-parted, yellow corolla, 8 undeveloped stamens, and a rounded ovary bearing the style and stigma. 'Perfect' flowers are a cross between the two and contain both male and female reproductive organs.  Persimmon fruit matures late in the fall and can stay on the tree until winter. In color, the ripe fruit of the cultivated strains range from glossy light yellow-orange to dark red-orange depending on the species and variety. They similarly vary in size from in diameter, and in shape the varieties may be spherical, acorn-, or pumpkin-shaped. The flesh is astringent until fully ripe and is yellow, orange, or dark-brown in color. The calyx generally remains attached to the fruit after harvesting, but becomes easy to remove once the fruit is ripe. The ripe fruit has a high glucose content and is sweet in taste. Like the tomato, persimmons are not commonly considered to be berries, but morphologically the fruit is in fact a berry.

Selected species.

While many species of "Diospyros" bear fruit inedible to humans or only occasionally gathered, the following are grown for their edible fruit:

"Diospyros kaki" (Asian persimmon, Japanese persimmon).

Asian or Japanese persimmon ("Diospyros kaki") is the commercially most important persimmon, and is native to Japan, China, and Korea. It is deciduous, with broad, stiff leaves, and is known as the "shizi" (柿子 in Chinese), and also as the Japanese Persimmon or kaki (柿) in Japanese. Its fruits are sweet and slightly tangy with a soft to occasionally fibrous texture. Cultivation of the fruit extended first to other parts of Asia, India and Nepal, and it was later introduced to California and southern Europe in the 1800s and to Brazil in the 1890s.  Numerous cultivars have been selected. Some varieties are edible in the crisp, firm state but it has its best flavor when allowed to rest and soften slightly after harvest. The Japanese cultivar 'Hachiya' is widely grown. The fruit has a high tannin content, which makes the unripe fruit astringent and bitter. The tannin levels are reduced as the fruit matures. Persimmons like 'Hachiya' must be completely ripened before consumption. When ripe, this fruit comprises thick, pulpy jelly encased in a waxy thin-skinned shell.  "Sharon fruit" (named after the Sharon plain in Israel) is the marketing name for the Israeli-bred cultivar 'Triumph'. As with most commercial pollination-variant-astringent persimmons, the fruit are ripened off the tree by exposing them to carbon dioxide. The "sharon fruit" has no core, is seedless and particularly sweet, and can be eaten whole.  In the Valencia region of Spain, there is a variegated form of kaki called the "Ribera del Xuquer", "Spanish persimmon", or "Rojo Brillante" ("bright red").

"Diospyros lotus" (date-plum).

Date-plum ("Diospyros lotus"), also known as lotus persimmon, is native to southwest Asia and southeast Europe. Its English name probably derives from Persian "Khormaloo" خرمالو literally "date-plum", referring to the taste of this fruit, which is reminiscent of both plums and dates.

"Diospyros virginiana" (American persimmon).

American persimmon ("Diospyros virginiana") is native to the eastern United States. Harvested in the fall or after the first frost, its fruit is eaten fresh, in baked goods, or in steamed puddings, and sometimes its timber is used as a substitute for true ebony or African blackwood (e.g., in musical instruments).

"Diospyros nigra" (black sapote / chocolate pudding fruit / black persimmon).

Black sapote ("Diospyros nigra") is native to Mexico. Its fruit has green skin and white flesh that turns dark brown to black when ripe.

"Diospyros discolor".

The Mabolo or Velvet-apple ("Diospyros discolor") is native to East Asia, ranging from China down into the Philippines. It is bright red when ripe. In China, it is referred to as "shizi". It is also known as Korean mango.

"Diospyros peregrina" (Indian persimmon).

Indian persimmon ("Diospyros peregrina") is a slow-growing tree, native to coastal West Bengal. The fruit is green and turns yellow when ripe. It is relatively small with an unremarkable flavor and is better known for uses in traditional medicine rather than culinary applications.

"Diospyros texana" (Texas persimmon).

Texas persimmon ("Diospyros texana") is native to central and west Texas and southwest Oklahoma in the United States, and eastern Chihuahua, Coahuila, Nuevo León, and Tamaulipas in northeastern Mexico. The fruit of "D. texana" are black on the outside (as opposed to just on the inside as with the Mexican persimmon) subglobose berries with a diameter of ripen in August. The fleshy berries become edible when they turn dark purple or black, at which point they are sweet and can be eaten from the hand or made into pudding or custard.

Fruit.

Commercially and in general, there are two types of persimmon fruit: astringent and non-astringent.  The heart-shaped Hachiya is the most common variety of astringent persimmon. Astringent persimmons contain very high levels of soluble tannins and are unpalatable if eaten before completely softened, though the sweet, delicate flavor of fully ripened persimmons of varieties that are astringent when unripe is particularly relished. The astringency of tannins is removed in various ways. Examples include ripening by exposure to light for several days and wrapping the fruit in paper (probably because this increases the ethylene concentration of the surrounding air). Ethylene ripening can be increased in reliability and evenness, and the process can be greatly accelerated by adding ethylene gas to the atmosphere in which the fruit is stored. For domestic purposes, the most convenient and effective process is to store the ripening persimmons in a clean, dry container together with other varieties of fruit that give off particularly large quantities of ethylene while they are ripening; apples and related fruits such as pears are effective, and so are bananas and several others. Other chemicals are used commercially in artificially ripening persimmons or delaying their ripening. Examples include alcohol and carbon dioxide, which change tannin into the insoluble form. Such bletting processes sometimes are jump-started by exposing the fruit to cold or frost. The resultant cell damage stimulates the release of ethylene, which promotes cellular wall breakdown.  Astringent varieties of persimmons also can be prepared for commercial purposes by drying. Tanenashi fruit will occasionally contain a seed or two, which can be planted and will yield a larger, more vertical tree than when merely grafted onto the "D. virginiana" rootstock most commonly used in the U.S. Such seedling trees may produce fruit that bears more seeds, usually 6 to 8 per fruit, and the fruit itself may vary slightly from the parent tree. Seedlings are said to be more susceptible to root nematodes.  The non-astringent persimmon is squat like a tomato and is most commonly sold as "fuyu". Non-astringent persimmons are not actually free of tannins as the term suggests but rather are far less astringent before ripening and lose more of their tannic quality sooner. Non-astringent persimmons may be consumed when still very firm and remain edible when very soft.  There is a third type, less commonly available, the pollination-variant non-astringent persimmons. When fully pollinated, the flesh of these fruit is brown inside—known as "goma" in Japan—and the fruit can be eaten when firm. These varieties are highly sought after. Tsurunoko, sold as "chocolate persimmon" for its dark brown flesh, Maru, sold as "cinnamon persimmon" for its spicy flavor, and Hyakume, sold as "brown sugar", are the three best known.  Before ripening, persimmons usually have a "chalky" or bitter taste.

Production.

In 2018, world production of persimmons was 7.9 million tonnes, with China alone accounting for 80% of this total (table). Other significant producers were Spain and South Korea (table).

Culinary uses.

Persimmons are eaten fresh, dried, raw or cooked. When eaten fresh, they are usually eaten whole like an apple in bite-size slices and may be peeled. One way to consume ripe persimmons, which may have soft texture, is to remove the top leaf with a paring knife and scoop out the flesh with a spoon. Riper persimmons can also be eaten by removing the top leaf, breaking the fruit in half, and eating from the inside out. The flesh ranges from firm to mushy, and, when firm owing to being unripe, has an apple-like crunch. American persimmons ("Diospyros virginiana") and "Diospyros digyna" are completely inedible until they are fully ripe.  In China, Korea, Japan and Vietnam, persimmons after harvesting are prepared using traditional hand-drying techniques outdoors for two to three weeks. The fruit is then further dried by exposure to heat over several days before being shipped to market, to be sold as dried fruit. In Japan, the dried persimmon fruit is called "hoshigaki", in China "shìbǐng" 柿饼, in Korea "gotgam", and in Vietnam "hồng khô". It is eaten as a snack or dessert and used for other culinary purposes.  In Korea, dried persimmon fruits are used to make the traditional Korean spicy punch "sujeonggwa", while the matured, fermented fruit is used to make a persimmon vinegar called "gamsikcho".  In Taiwan, fruits of astringent varieties are sealed in jars filled with limewater to get rid of bitterness. Slightly hardened in the process, they are sold under the name "crisp persimmon" ("cuishi") or "water persimmon" ("shuishizi"). Preparation time is dependent upon temperature (5 to 7 days at.  For centuries, Japanese have consumed persimmon leaf tea (Kaki-No-Ha Cha) made from the dried leaves of "kaki" persimmons (Diospyros kaki). In some areas of Manchuria and Korea, the dried leaves of the fruit are used for making tea. The Korean name for this tea is "ghamnip cha".  In the Old Northwest of the United States, persimmons are harvested and used in a variety of dessert dishes, most notably pies. They can be used in cookies, cakes, puddings, salads, curries and as a topping for breakfast cereal. Persimmon pudding is a baked dessert made with fresh persimmons that has the consistency of pumpkin pie but resembles a brownie and is almost always topped with whipped cream. An annual persimmon festival, featuring a persimmon pudding contest, is held every September in Mitchell, Indiana.  Persimmons may be stored at room temperature where they will continue to ripen. In northern China, unripe persimmons are frozen outside during winter to speed up the ripening process.

Nutrient and phytochemical content.

Compared to apples, persimmons have higher levels of dietary fiber and some dietary minerals, but overall are not a significant source of micronutrients, except for manganese (17% of the Daily Value, DV) and provitamin A beta-carotene (10% DV, table for raw Japanese persimmons per 100 gram amount). In a 100 gram amount, raw American persimmons are a rich source of vitamin C (80% DV) and iron (19% DV).  Persimmon fruits contain phytochemicals, such as catechin, gallocatechin and betulinic acid.

Unripened persimmons and bezoars.

Unripened persimmons contain the soluble tannin shibuol, which, upon contact with a weak acid, polymerizes in the stomach and forms a gluey coagulum, a "foodball" or phytobezoar, that can affix with other stomach matter. These phytobezoars are often very hard and almost woody in consistency. More than 85% of phytobezoars are caused by ingestion of unripened persimmons. Persimmon bezoars (diospyrobezoars) often occur in epidemics in regions where the fruit is grown.

Wood.

Though persimmon trees belong to the same genus as ebony trees, persimmon tree wood has a limited use in the manufacture of objects requiring hard wood. It is hard, but cracks easily and is somewhat difficult to process. Persimmon wood is used for paneling in traditional Korean and Japanese furniture.  In North America, the lightly colored, fine-grained wood of "D. virginiana" is used to manufacture billiard cues and textile shuttles. It is also used to produce the shafts of some musical percussion mallets and drumsticks. Persimmon wood was also heavily used in making the highest-quality heads of the golf clubs known as "woods" until the golf industry moved primarily to metal woods in the last years of the 20th century. In fact, the first metal woods made by TaylorMade, an early pioneer of that club type, were branded as "Pittsburgh Persimmons". Persimmon woods are still made, but in far lower numbers than in past decades. Over the last few decades persimmon wood has become popular among bow craftsmen, especially in the making of traditional longbows. Persimmon wood is used in making a small number of wooden flutes and eating utensils such as wooden spoons and cornbread knives (wooden knives that may cut through the bread without scarring the dish).  Like some other plants of the genus "Diospyros", older persimmon heartwood is black or dark brown in color, in stark contrast to the sapwood and younger heartwood, which is pale in color.

Folklore.

In Ozark folklore, the severity of the upcoming winter is said to be predictable by slicing a persimmon seed and observing the cutlery-shaped formation within it. In Korean folklore the dried persimmon (gotgam, Korean: 곶감) has a reputation for scaring away tigers.

In popular culture.

Persimmons are the favourite food of the title character of the film "Okja".

The persimmon (sometimes spelled persimon) is the edible fruit of a number of species of trees in the genus "Diospyros". The most widely cultivated of these is the Asian or Japanese persimmon, "Diospyros kaki". "Diospyros" is in the family Ebenaceae, and a number of non-persimmon species of the genus are grown for ebony timber.

Le kaki, appelé aussi plaquemine du Japon, plaquemine de Chine, ou anciennement figue caque, est le fruit du plaqueminier du Japon ("Diospyros kaki"), de la famille des Ébénacées. Il est traditionnellement produit en Asie de l'Inde au Japon et spécialement en Chine, à Taïwan et en Corée.


Permanent collections.

Sculptures.

Rodin's sculptures are the work of an artist who chose to defy the norms of his time. Among the works of his youth, "Man with a Broken Nose" appears out of step with contemporary aesthetic norms, while "The Age of Bronze" rejects contemporary mechanisms of physical expression. This absence of artifice, like the nudity of "The Thinker" or "Adam and Eve" guarantees the timelessness of Rodin's works.  The artist also stands out by the monumental aspect of some of his works: "Balzac", "The Burghers of Calais" or the impressive, unfinished "The Gates of Hell," which contains many elements representing the major works of Rodin ("The Thinker, Ugolino, The Kiss" or "the Three Shades").

Drawings.

The graphic collection at the Musée Rodin contains around 7,000 drawings. They can be associated with different styles and periods: observation of landscapes, fantasy works inspired by Dante or Baudelaire, numerous erotic nudes or even portraits.

Photography.

The Musée Rodin preserves an important collection of 25,000 photographs. Among these, 7,000 were collected by Rodin himself. The artist showed indeed a great interest for this science and art, and he has collaborated with many photographers, such as Eugène Druet, Jacques-Ernest Bulloz, Adolphe Braun or Edward Steichen.  Subjects and themes are varied, Rodin's personal albums attest to his centres of interest and artistic sources, while the portraits and newspaper photographs illustrate his work and his life. Above all, these photographs are a great source to learn what happened in the studio between 1877 and Rodin's death, in 1917.

Camille Claudel room.

The Camille Claudel room contains such Claudel works as the 1913 casting of "The Mature Age" (1898), "The Wave" (1897), "Sakountala" (1905), and an 1892 casting of "Bust of Rodin" (1888–89).  Claudel, a student and model for Rodin, and soon his collaborator, associate, and lover, worked with Rodin from 1884 until the early 1890s. They kept in close contact until 1899.

Rodin as a collector.

During the twenty last years of his life, as he was living in Meudon, Rodin started a collection of ancient works of art from Egypt, Greece and Rome, then later from the Far East. As the collection was growing, the different pieces invaded the studio and his house, replacing the casts after Antique statues. As Rodin's fame grew, the commissions he received enabled him to continue his collection, reaching over 6.000 works in 1917.  In addition, Rodin's friendships and tastes led him to surrounding himself with works by the Naturalists (Théodule Ribot, Alfred Roll) and Symbolists (Eugène Carrière, Charles Cottet...). Through a series of exchanges made with his artists friends, Rodin owned works of art from Jules Dalou, Alexandre Falguière or Jean-Paul Laurens. He also realised important purchases: three Van Gogh's (including "Père Tanguy", late 1887), Renoir's "Nude in the Sunlight" and Monet's "Belle-Île".

Temporary exhibitions.

Contemporary art exhibitions.

Recently, contemporary art exhibitions are also organized, as it was done as early as 1949 when the first Salon de la jeune sculpture took place at the Musée Rodin. Artists such as Anthony Caro, Eugène Dodeigne, Étienne Bossut exhibited at the museum. Bill Viola, Adel Abdessemed and Mircea Cantor have been invited to screen videos in the park for the « Nuit des musées ». In 2010, artworks by Belgian artist Wim Delvoye were exhibited, as well as a program of video-performances by artists such as Vito Acconci, Sanja Iveković, Marina Abramović and Mona Hatoum. A Henry Moore exhibition, dedicated to his studio and small sculptures, ran there from October 2010 to February 2011.

Museum locations.

Hôtel Biron, Paris.

First opened to the public on 4 August 1919, the Musée Rodin was housed in a mansion, formerly called the Hôtel Peyrenc de Moras, designed with the lines of classical architecture and ornamented with rocaille decoration. It was built in the Rue de Varenne, between 1727 and 1732. From 1788, the Hôtel was occupied by a series of owners and tenants. In 1820, the Duchess of Charost sold the entire property to three nuns belonging to a religious congregation, the Society of the Sacred Heart of Jesus. A boarding school for girls was opened and the decorations were progressively sold. Between 1820 and 1904, several buildings were constructed on the estate, the Chapel in particular, designed by the architect Jean Juste Gustave Lisch and achieved in 1876.  The Society was dissolved in 1904 due to the'religious orders' law involving the separation of church and state which prohibited religious orders from teaching. The sisters were evicted and the estate was put up for sale. Awaiting a buyer, tenants were allowed to occupy the building and among them, we can find several artists: Jean Cocteau, Henri Matisse, Isadora Duncan...Rainer Maria Rilke, whose future wife Clara Westhoff was living in the Hôtel, has been the first to tell Rodin about the estate. Thus, in 1908, the sculptor rented four ground-floor rooms to use as his studios. From 1911 onwards, he occupied the whole building. In 1911, as the French state had committed itself to purchasing the Hôtel Biron, Rodin started to negotiate with it. The artist announced officially his intention to donate all his works to the French state, as well as his drawings and his collection of antiquities in the condition that the State keeps all these collections at the Hôtel Biron, which will become the Musée Rodin in exchange of the right to reside there all his life.  In 1916, the French Assembly passed a law permitting the State to accept the donations and allocated the mansion and its garden to a museum. Léonce Bénédite was appointed executor of the sculptor's will: his tasks were to manage Rodin's artistic heritage and to supervise the organisation of the future museum.  Listed as a historical monument in 1926, the Hôtel Biron and its grounds have since undergone major renovation and restoration work, to better assert their role as a museum. The most recent scheme is of course the huge restoration plan which began in 2012 and will end with the reopening of the Hôtel Biron on 12 November 2015, for Rodin's 175th birthday. The renovations cost 16 million euro ($17.4 million), and were hailed as a "moral duty" by France's Culture Minister Fleur Pellerin.

Musée Rodin in Meudon.

On December 19, 1895, Rodin purchased a Louis XIII-style house in brick and stone, built on the heights of Meudon and called "La Villa des Brillants". In 1900, almost 50 people, including sculptor's assistants, workers and casters, were employed there by Rodin and, although he continued to go to his Paris studios daily, his major creative work was done in Meudon. The place became soon a major place of attraction for friends, admirers or celebrities from France or abroad. It is also in Meudon that Rodin and his wife, Rose Beuret, have chosen to be buried.  After the death of Rodin, the villa and the studio also became a museum, open three days per week. Visitors can discover the atmosphere of the studio and the place where Rodin liked to live and work. Inaugurated in 1948, the museum also permits to glimpse numerous plasters, including casts for Rodin's monumental works, such as the "Burghers of Calais" and the "Gates of Hell" which allow to discover the different steps of the creative process.

References.

Notes  Bibliography

The Musée Rodin in Paris, France, is a museum that was opened in 1919, primarily dedicated to the works of the French sculptor Auguste Rodin. It has two sites: the Hôtel Biron and surrounding grounds in central Paris, as well as just outside Paris at Rodin's old home, the Villa des Brillants at Meudon, Hauts-de-Seine. The collection includes 6,600 sculptures, 8,000 drawings, 8,000 old photographs and 7,000 objets d’art. The museum receives 700,000 visitors annually.

Le musée Rodin est un musée assurant depuis 1919 la conservation et la diffusion de l’œuvre d’Auguste Rodin (1840-1917). À travers ses deux sites, l'hôtel Biron de la rue de Varenne dans le à Paris et la villa des Brillants à Meudon (Hauts-de-Seine), l’établissement conserve une collection composée de près de,, anciennes et d’art. Avec par an, le musée Rodin compte parmi les musées français les plus importants.


Biography.

Yerofeyev was born in the maternity hospital of Niva-3 by Kandalaksha, Murmansk Oblast, a settlement of "special settlers" employed in the construction of a hydroelectric power station on the Niva River. The record made in his birth certificate declares his birthplace to be his parents' place of residence: Chupa railway station, Loukhsky District, Karelian ASSR.  His father was imprisoned during Stalin's purges but survived 16 years in the gulags. Most of Yerofeyev's childhood was spent in Kirovsk, Murmansk Oblast. He managed to enter the philology department of the Moscow State University but was expelled from the university after a year and a half because he did not attend compulsory military training. Later he studied in several more institutes in different towns, including Kolomna and Vladimir, but he never managed to graduate from any, usually being expelled due to his "amoral behaviour".  Between 1958 and 1975, Yerofeyev lived without propiska in various towns in Russia, Ukraine, Belarus, and Lithuania, also spending some time in Uzbekistan and Tadjikistan, doing different low-level and underpaid jobs; for a time he lived and worked in the Muromtsev Dacha in Moscow. He started writing at the age of 17; in the 1960s he unsuccessfully submitted several articles on Ibsen and Hamsun to literary magazines.

Literary legacy.

Yerofeyev is best known for his 1969 "poem in prose" (ironical assignment of the genre) "Moscow-Petushki" (several English translations exist, including "Moscow to the End of the Line" and "Moscow Stations"). It is an account of a journey from Moscow to Petushki (Vladimir Oblast) by electric train, one of many futile attempts to visit his small son: each time such a journey becomes soaked in alcohol and fails. During the trip, the hero becomes involved in philosophical discussions about drinking, recounts some of the fantastic escapades he participated in, including declaring war on Norway, charting the drinking statistics of his colleagues when leader of a cable-laying crew, and obsessing about the woman he loves.  Referred to by David Remnick as "the comic high-water mark of the Brezhnev era", the poem was published for the first time in 1973 in a Russian-language magazine in Jerusalem. It was not published in the Soviet Union until 1989.  Of note is his smaller 1988 work "My Little Leniniana" (Моя маленькая лениниана, Moya malenkaya Leniniana), which is a collection of quotations from Lenin's works and letters, which shows the unpleasant parts of the character of the "leader of the proletariat". Alexander Bondarev tells the story of its origin.  Yerofeyev also claimed to have written in 1972 a novel "Shostakovich" about the famous Russian composer Dmitri Shostakovich, but the manuscript was allegedly stolen in a train. The novel has never been found. Before his death of throat cancer Yerofeyev finished a play called "Walpurgisnacht, or the Steps of the Commander" ("Вальпургиева ночь или Шаги командора") and was working on another play about Fanny Kaplan.

Personal life and death.

Venedikt Yerofeyev was married twice, to Valentina Vasilevna Zimakova and Galina Pavlovna Nosova. In 1966 Yerofeyev's wife, Valentina Zimakova gave birth to a son - Venedikt Venediktovich Yerofeyev. Galina Nosova died three years after Yerofeyev - having thrown herself off the balcony of her 13th floor apartment in Moscow.  In 1985 Yerofeyev was diagnosed with throat cancer. Doctors operated on him, after which he could only speak using an electro-larynx. A film was made about Moskva-Petushki in the last years of Yerofeyev's life and he can be seen speaking with the help of this apparatus. Yerofeyev died five years after he was first diagnosed with the disease, on 11 May 1990, at the Russian Oncological Centre in Moscow. He is buried in Kuntsevsky cemetery.

Venedikt Vasilyevich Yerofeyev, also Benedict Erofeev or Erofeyev (; 24 October 1938 in Niva-3 settlement, suburb of Kandalaksha – 11 May 1990 in Moscow) was a Russian writer and Soviet dissident.

Venedikt Vassilievitch Erofeïev (en ), est un écrivain soviétique, né le à Kirovsk (oblast de Mourmansk) et décédé le à Moscou.


History.

In acknowledgement of his loyalty, James VI of Scotland (James I of England), conferred on the Hon. Claud Hamilton, third son of James Hamilton, 2nd Earl of Arran, the title Lord Paisley. His son James Hamilton was created Lord Abercorn on 5 April 1603, then on 10 July 1606 he was made Earl of Abercorn and Lord of Paisley, Hamilton, Mountcastell and Kilpatrick.  His successor, the 2nd Earl of Abercorn, was additionally created Lord Hamilton, Baron of Strabane, in the Peerage of Ireland, on 8 May 1617. He resigned this dignity to his younger brother in 1633; the brother's heirs inherited the Earldom and other titles in 1680, in the person of Claud Hamilton, 4th Earl of Abercorn. He was attainted in Ireland in 1691, and the Barony of Strabane forfeited, but his brother Charles Hamilton, 5th Earl of Abercorn, obtained a reversal of the attainder and recovered in 1692.  The 6th earl was at his accession an Irish baronet, "of Dunalong in the County of Tyrone, and of Nenagh in the County of Tipperary" (1660). He was additionally created Baron Mountcastle and Viscount Strabane, in the Peerage of Ireland, on 2 September 1701. The 7th earl became the first of the Earls of Abercorn to be invested a Privy Counsellor, having been appointed to both the English and Irish Privy Councils. The 8th earl was created Viscount Hamilton, of Hamilton, in the Peerage of Great Britain on 24 August 1786. He was succeeded by his nephew, who was created Marquess of Abercorn in the Peerage of Great Britain on 15 October 1790, after having sat in the House of Commons as MP for East Looe and for St Germans. He was made a Knight of the Garter in 1805.  The 2nd Marquess, who had been given the Garter in 1844, served as Lord Lieutenant of Ireland from 1866 to 1868 (and again from 1874 to 1876); and on 10 August 1868, during his first term, he was created Marquess of Hamilton, of Strabane, and Duke of Abercorn (in the Peerage of Ireland). His successor, the 2nd Duke, continued the family tradition by being awarded the Garter in 1892; the 3rd Duke served as MP for Londonderry and as Governor of Northern Ireland, along with being created a Knight of St Patrick and given the Garter. Currently, the holder of the Dukedom is James Hamilton, 5th Duke of Abercorn, also a Knight of the Garter.  Of the subsidiary titles above, Marquess of Hamilton is the courtesy title of the heir apparent, and Viscount Strabane that of his heir-apparent.  The Dukes of Abercorn also claim the French title of "Duc de Châtellerault", as heirs-male of the 2nd Earl of Arran, who was granted the title in 1548 by Henry II of France. Additionally, since the death of William Hamilton, 2nd Duke of Hamilton, in 1651, the Earls, Marquesses, and Dukes of Abercorn have been the rightful claimants to the peerage dignities of Earl of Arran (of the 1503 creation) and Lord Hamilton (of the 1445 creation), both in the Peerage of Scotland, as the most senior heirs-male of James Hamilton, Duke of Châtellerault, and this title is reflected in their coat of arms, with an inescutcheon of three fleur-de-lys and a French ducal crown.  Diana, Princess of Wales was a great-granddaughter of the 3rd Duke of Abercorn.  The family seat is Baronscourt (usually known locally as Baronscourt Castle), a neo-Classical country house on the Barons Court Estate near Newtownstewart, Omagh, a village near Strabane, County Tyrone, Northern Ireland. The traditional burial place of the Dukes of Abercorn and their families is the cemetery at Baronscourt Parish Church.

The title Duke of Abercorn () is a title in the Peerage of Ireland. It was created in 1868 and bestowed upon James Hamilton, 2nd Marquess of Abercorn. Although the Dukedom is in the Peerage of Ireland, it refers to Abercorn, West Lothian, and the Duke also bears four titles in Peerage of Scotland and two in the Peerage of Great Britain, and is one of only three peers who have titles in those three peerages. The Duke of Abercorn also claims the French title of Duke of Châtellerault, created in 1548.

Le titre de duc d'Abercorn a été créé en 1868, dans la pairie d'Irlande, pour James Hamilton. Le titre subsidiaire à celui de duc est marquis d'Hamilton.


TI-89.

The TI-89 is a graphing calculator developed by Texas Instruments in 1998. The unit features a 160×100 pixel resolution LCD screen and a large amount of flash memory, and includes TI's "Advanced Mathematics Software". The TI-89 is one of the highest model lines in TI's calculator products, along with the TI-Nspire. In the summer of 2004, the standard TI-89 was replaced by the TI-89 Titanium.  The TI-89 runs on a 16-bit microprocessor, the Motorola 68000, which nominally runs at 10, 12 MHz, depending on the calculator's hardware version. Texas Instruments has allocated 256 total kB of RAM for the unit (190 kB of which are available to the user) and 2 MB of flash memory (700 kB of which is available to the user). The RAM and Flash ROM are used to store expressions, variables, programs, tables, text files, and lists.  The TI-89 is essentially a TI-92 Plus with a limited keyboard and smaller screen. It was created partially in response to the fact that while calculators are allowed on many standardized tests, the TI-92 was considered a computer due to the QWERTY layout of its keyboard. Additionally, some people found the TI-92 unwieldy and overly large. The TI-89 is significantly smaller—about the same size as most other graphing calculators. It has a flash ROM, a feature present on the TI-92 Plus but not on the original TI-92.

User features.

The major advantage of the TI-89 over lower-model TI calculators is its built-in computer algebra system, or CAS. The calculator can evaluate and simplify algebraic expressions symbolically. For example, entering codice_1 returns formula_1. The answer is "prettyprinted" by default; that is, displayed as it would be written by hand (e.g. the aforementioned formula_1 rather than codice_1). The TI-89's abilities include:  In addition to the standard two-dimensional function plots, it can also produce graphs of parametric equations, polar equations, sequence plots, differential equation fields, and three-dimensional (two independent variable) functions.

Programming.

The TI-89 is directly programmable in a language called TI-BASIC, TI's derivative of BASIC for calculators. With the use of a PC, it is also possible to develop more complex programs in Motorola 68000 assembly language or C, translate them to machine language, and copy them to the calculator. Two software development kits for C programming are available; one is TI Flash Studio, the official TI SDK, and the other is TIGCC, a third-party SDK based on GCC.  Since the TI-89's release in 1998, thousands of programs for math, science, or entertainment have been developed. Many available games are generic clones of "Tetris", "Minesweeper", and other classic games, but some programs are more advanced: for example, a ZX Spectrum emulator, a chess-playing program, a symbolic circuit simulator, and a clone of "Link's Awakening". One of the most popular and well-known games is Phoenix. Many calculator games and other useful programs can be found on TI-program sharing sites. Ticalc.org is a major one that offers thousands of calculator programs.

Hardware versions.

There are four hardware versions of the TI-89. These versions are normally referred to as HW1, HW2, HW3, and HW4 (released in May 2006). Entering the key sequence [F1] [A] displays the hardware version. Older OS versions (before 2.00) don't display anything about the hardware version unless the calculator is HW2 or later. The differences in the hardware versions are not well documented by Texas Instruments. HW1 and HW2 correspond to the original TI-89; HW3 and HW4 are only present in the TI-89 Titanium.  The most significant difference between HW1 and HW2 is in the way the calculator handles the display. In HW1 calculators there is a video buffer that stores all of the information that should be displayed on the screen, and every time the screen is refreshed the calculator accesses this buffer and flushes it to the display (direct memory access). In HW2 and later calculators, a region of memory is directly aliased to the display controller (memory-mapped I/O). This allows for slightly faster memory access, as the HW1's DMA controller used about 10% of the bus bandwidth. However, it interferes with a trick some programs use to implement grayscale graphics by rapidly switching between two or more displays (page-flipping). On the HW1, the DMA controller's base address can be changed (a single write into a memory-mapped hardware register) and the screen will automatically use a new section of memory at the beginning of the next frame. In HW2, the new page must be written to the screen by software. The effect of this is to cause increased flickering in grayscale mode, enough to make the 7-level grayscale supported on the HW1 unusable (although 4-level grayscale works on both calculators).  HW2 calculators are slightly faster because TI increased the nominal speed of the processor from 10 MHz to 12 MHz. It is believed that TI increased the speed of HW4 calculators to 16 MHz, though many users disagree about this finding.  Another difference between HW1 and HW2 calculators is assembly program size limitations. The size limitation on HW2 calculators has varied with the AMS version of the calculator. As of AMS 2.09 the limit is 24k. Some earlier versions limited assembly programs to 8k, and the earliest AMS versions had no limit. HW1 calculators have no hardware to enforce the limits, so it is easy to bypass them in software. There are unofficial patches and kernels that can be installed on HW2 calculators to remove the limitations.

TI-89 Titanium.

The TI-89 Titanium was released in the summer of 2004, and has largely replaced the popular classic TI-89. The TI-89 Titanium is referred to as HW3 and uses the corresponding AMS 3.x. In 2006, new calculators were upgraded to HW4 which was supposed to offer increases in RAM and speeds up to 16 MHz, but some benchmarks made by users reported speeds between 12.85–14.1 MHz.  The touted advantages of the TI-89 Titanium over the original TI-89 include two times the flash memory (with over three times as much available to the user). The TI-89 Titanium is essentially a Voyage 200, except it doesn't have an integrated keyboard. The TI-89 Titanium also has a USB On-The-Go port, for connectivity to other TI-89 Titanium calculators, or to a computer (to store programs or update the operating system). The TI-89 Titanium also features some pre-loaded applications, such as "CellSheet", a spreadsheet program also offered with other TI calculators. The Titanium has a slightly updated CAS, which adds a few more mathematical functions, most notably implicit differentiation. The Titanium also has a slightly differing case design from that of the TI-89 (the Titanium's case design is similar to that of the TI-84 Plus).  There are some minor compatibility issues with C and assembly programs developed for the original TI-89. Some have to be recompiled to work on the Titanium due to various small hardware changes, though in most cases the problems can be fixed by using a utility such as GhostBuster, by Olivier Armand and Kevin Kofler. This option is generally preferred as it requires no knowledge of the program, works without the need of the program's source code, is automated, and doesn't require additional computer software. In some cases, only one character needs to be changed (the ROM base on TI-89 is at 0x200000, whereas the TI-89 Titanium is at 0x800000) by hand or by patcher. Most, if not all, of these problems are caused by the mirror memory (ghost space) or lack thereof.

Use in schools.

United Kingdom.

The Joint Council for Qualifications publish examination instructions on behalf of the main examination boards in England, Wales and Northern Ireland. These instructions state that a calculator used in an examination must not be designed to offer symbolic algebra manipulation, symbolic differentiation or integration. This precludes use of the TI-89 or TI-89 Titanium in examinations, but it may be used as part of classroom study. The SQA give the same instructions for examinations in Scotland.

United States.

In the United States, the TI-89 is allowed by the College Board on all calculator-permitted tests, including the SAT, some SAT Subject Tests, and the AP Calculus, Physics, Chemistry, and Statistics exams. However, the calculator is banned from use on the ACT, the PLAN, and in some classrooms. The TI-92 series, with otherwise comparable features, has a QWERTY keyboard that results in it being classified as a computer device rather than as a calculator.

The TI-89 and the TI-89 Titanium are graphing calculators developed by Texas Instruments (TI). They are differentiated from most other TI graphing calculators by their computer algebra system, which allows symbolic manipulation of algebraic expressions—equations can be solved in terms of variables, whereas the TI-83/84 series can only give a numeric result.

La TI-89 est une calculatrice graphique programmable commercialisée par Texas Instruments à partir de 1998. Elle s'appuie sur une plate-forme matérielle proche et le même logiciel que la TI-92 Plus. Elle représente donc une variante plus compacte de cette dernière, au format traditionnel des calculatrices graphiques Texas Instruments. En 2003, la TI-89 Titanium a apporté quelques améliorations à l'ancien modèle (plus de mémoire, connectique USB, applications scientifiques fournies). La TI-89 est considérée comme un succès marquant de Texas Instruments au tournant du troisième millénaire.


Locrian tribe.

The city of Locri in Calabria (Italy), also known in antiquity as "Epizephyrian Locris", was a colony founded by the Locrians in Magna Graecia. There is some disagreement over whether it was those from Opuntian Locris or from Ozolian Locris who were responsible.

Ancient Locris.

The territory of the Locrians was divided into three by Doris and Phocis, perhaps due to an early invasion of a contiguous Locrian state. This fact, combined with the region's infertility, meant that the Locrians tended to be dominated by their neighbours, and played little part in Greek history.  To the south-west of Phocis was Ozolian Locris, situated on the north coast of the Gulf of Corinth, between Naupactus and Crisa. The main cities of Ozolian Locris were Amphissa and Naupactus which was its seaport. To the north east of Phocis was Opuntian Locris, named after its main city, Opus. Finally, to the north of Phocis was Epicnemidian Locris, situated near the pass of Thermopylae.  The Opuntian Locris and the Epicnemidian Locris are often regarded as one people, separate in customs and integration to the Hellenic culture from the Ozolian Locris, considered as the less civilised of the two. The territories of the Opuntian Locris and the Epicnemidian Locris were not a continuous unit but were separated from one another by Phocis

Ozolian Locris.

The main towns of Ozolian Locris were Amphissa and Naupactus. Today, the area is part of Aetolia-Acarnania and Phocis.

Opuntian Locris.

The main towns of Opuntia Locris were Opus and Larymna. Today, Opuntian Locris is part of modern Phthiotis.

Epicnemidian Locris.

The main towns of Epicnemidian Locris were Nicaea and Thronium. Today, Epicnemidian Locris is part of modern Phthiotis.

Province.

The province of Locris () was one of the provinces of the Phthiotis Prefecture. Its capital was the town Atalanti. Its territory corresponded with that of the current municipalities Amfikleia-Elateia, Lokroi, and Molos-Agios Konstantinos. It was abolished in 2006.

Locris (; ; ) was a region of ancient Greece, the homeland of the Locrians, made up of three distinct districts.

La Locride (en grec ancien / ) est une ancienne région de Grèce centrale. Elle fut divisée en deux parties, la Locride orientale et la Locride occidentale, par les Phocidiens d'origine dorienne au


Nomenclature.

Various terms for the diatonic button accordion are used in different parts of the English-speaking world.  To simplify matters and avoid ambiguity, in the remainder of this article the term diatonic button accordion, or DBA, will be used.

Glossary.

The following definitions will assist understanding of this article.

Action.

Most diatonic button accordions have a "single-action" (or bisonoric) keyboard, meaning that each button produces two notes: one when the bellows are pressed or pushed (closed) and another when the bellows are drawn or pulled (opened). In this respect, these instruments operate like a harmonica.  Other single-action or bisonoric members of the free-reed family include the German concertina, the Anglo-German (or "Anglo") concertina, the bandoneon, the Chemnitzer concertina (see concertina) and the mouth organ (harmonica).  There are varieties of diatonic button accordion that are double-action, such as the garmon.

Distribution of notes on the keyboard and range.

Because each button produces two notes, the diatonic scale can be covered in four buttons on a melody row.  For example, on a melody row pitched in C, the notes of the lower full octave of the instrument's range are assigned to four buttons as follows:  "Note: the first button in the example above, numbered 1, is likely to be the 3rd or 4th button in a row on an instrument."  When the bellows are pressed, every button produces a note from the major triad of the home key; in this case, the pattern CEG repeats itself throughout the keyboard. The remaining notes of the diatonic scale are produced when the bellows are drawn or pulled.  Since there are seven notes in the diatonic scale, and since each button produces two notes, the note pairings on the buttons change in each octave. In the second full octave of the instrument's range, E is paired with D (instead of with F in the first octave), and so on.  Because the range of each row is typically restricted to two complete octaves (with a few notes above and below), the inconsistent note pairing from one octave to the next remains manageable.  For detailed diagrams of typical note layouts on various types of diatonic button accordion, see melodeon.net

Available keys.

On a one-row DBA, music in a single major key and its relative minor can be played. For example, an instrument in D can play music in D major and B minor. However, the variety of music that can be played on a one-row instrument is wider than these facts might suggest: besides D major and B minor, our one-row instrument in D can play tunes in A Mixolydian and E Dorian, and tunes that use gapped scales, such as pentatonic tunes with a root of D, G or A.

Multi-row systems.

A one-row DBA has the advantages of being light and compact, but is by its nature limited to the notes of a single diatonic scale. Since the mid-to-late 19th century, instruments have been produced with more than one row in order to give players a greater choice of scales and tonalities.  Multi-row systems can be divided into two broad classes: "fourth-apart" systems and "semitone-apart" systems.

Fourth-apart systems.

Fourth-apart systems are the most widespread form of multi-row DBA. Moving from the outside the keyboard towards the inside, each row is pitched one-fourth higher than its neighbour. Conventionally, the outer keyboard row is specified first: for an example, on a G/C instrument the outer row is in the key of G, the inner row in C.  Commonly used in continental Europe are two-row systems in G/C and C/F and three-row systems in G/C/F, but many other permutations exist. In England, in the latter part of the 20th century, the D/G configuration became firmly established as the standard for interpreting traditional music of England, and particularly for the accompaniment of social and Morris dancing.  Three-row systems are also popular in Mexico and the United States (in Conjunto, Tejano, Zydeco and Cajun musics) and Colombia (in Vallenato and Folklor musics). Tunings include B/E/A, A/D/G, G/C/F, F/B/E and E/A/D. The three-row fourth-apart configuration is known as the "international system."  Multi-row systems obviously extend the range of tonalities available. But since many notes in the additional rows are "reversals" (duplicate notes produced by the opposite bellows action), multi-row systems allow greater flexibility of phrasing, since the player can often choose whether or not to change bellows direction, or to harmonize with a particular chord, by choosing a note from one row or another. Styles of play have developed in which row-crossing allows the bass side to be used to maximum effect, and the number of changes of bellows direction greatly reduced.

Accidentals and reversals.

Another feature designed to increase the flexibility of fourth-apart systems is the inclusion of notes that lie beyond the diatonic scales of each row, or "accidentals". These notes are most often operated by the buttons at the top of the keyboard (that is, closest to the player's chin), below the lowest notes of the scale.  Accidentals are sometimes placed on two extra buttons, or a shorter third row of four or more buttons, close to the bellows. The "Club system" developed by Hohner is a well-established example of this approach. Using the accidentals, and with the added modification of a "Gleichton" (unisonoric second-octave tonic in the centre of the middle row), this system allows players to obtain a fully chromatic scale – albeit in one direction only (draw).  Another use of such additional short rows, or half-rows, is to provide reversals (see above) to give the player greater flexibility.

Semitone-apart systems.

In semitone-apart systems, moving in from the outside the keyboard, each row is pitched a semitone higher than its neighbour. This configuration makes all the notes of the chromatic scale available. As a result, such instruments could strictly be termed chromatic (rather than diatonic) instruments. In practice, however, the restrictions imposed by the single action and layout of the keyboard lead most players to keep to a fairly restricted range of keys (albeit a wider range than is practical on most fourth-apart systems).  The earliest semitone-apart system was C/C, and many variants have been used over the years, notably D/D and G/G. However, since the mid-20th century two main systems have been in widespread use: the B/C system, used mainly for Irish and Scottish music, along with its larger cousin, the B/C/C system (which is now little used outside Scotland); and the C/D system, somewhat less common, used mainly in Irish music. (Irish-American musicians of the mid-20th century used this system with the position of the rows reversed, i.e. D/C.)

Bass systems.

Traditionally, one-row instruments have two or four buttons on the bass side, two-row instruments have eight, and three-row instruments twelve. As mentioned above, bass buttons are conventionally arranged in bass-note/chord pairs.  Some modern players, particularly in France, are driving a trend towards instruments with more complex bass systems, with as many as 16 or even 18 buttons. Sometimes these more elaborate systems will diverge from the single-action principle, and may feature bass notes only instead of bass-chord pairs of buttons.  The B/C/C system (also known as the "British Chromatic System") used in Scotland provides a notable example of the use of a double-action bass side with a single-action melody side: these instruments frequently feature a full Stradella bass system as used on piano accordions and chromatic button accordions.

Geographical variations on the DBA theme.

Several distinct variations of the DBA have developed in different regions of the world. These include the Russian garmon, the Steirische Harmonika or Slovenian-style accordion that is popular in Alpine regions of Europe, the Swiss Schwyzerörgeli and the Basque trikitixa; the last two combine single- and double-action (bisonoric and unisonoric) features. A common type of Italian "organetto" has a single melody row augmented with a very short half-row of between two and four buttons (often smaller in diameter than those on the main row) providing reversals only.

Advantages and disadvantages of the diatonic system.

DBAs have two main advantages when compared with chromatic accordions such as piano accordions and chromatic button accordions: 1) smaller size and lighter weight, 2) and the rhythmic effects inherent in the single ("push-pull") action.  The size and weight difference results from the nature of accordion reeds, which produce sound when air is moved through them in one direction only. In other words, for any key or button, two reeds are necessary: one to sound on the press, and one to sound on the draw. Because a double-action instrument sounds the same note on both press and draw, it needs two reeds for any given note in its range, where a single-action instrument—which sounds a different note on press and draw—requires only one. Any double-action instrument thus requires roughly twice as many reeds as an equivalent single-action instrument, making it larger and considerably heavier. (Another way to understand this difference is to consider the fact that a double-action instrument generally requires twice as many keys or buttons to produce a range of notes as a single-action instrument: for example, a piano accordion requires 8 keys (16 reeds) to sound a diatonic scale from C to C', where a DBA pitched in C requires 4 buttons (8 reeds) to produce the same notes.) This size and weight advantage is somewhat eroded in more complex, multi-row variants of the DBA, alluded to below.  The rhythmic effects inherent in the push-pull action are very well suited to the lively rhythms of dance music, and traditional dance music in particular. (On multi-row fourth-apart instruments, players can to some extent counter the natural push-pull effect with a row-crossing playing style that "smooths out" the musical phrasing; on semitone-apart systems, depending on the key of the piece being played, players may be obliged to adopt a smoother style.) Additionally, the close-togetherness of the notes on a DBA allow some tunes (particularly the quick folkdances and tunes written for the instrument) to be played with more ease and speed than on the more spread-out keyboards of chromatic- and piano-accordions. For example, playing an Irish reel might be easier on a B/C system diatonic than on a piano-accordion, and a Swiss "Schottisch" or "Ländler" might be easier to play on a "Schwyzerörgeli" than on a piano or even a chromatic due to the chordal/arpeggio phrases that fall naturally on the buttons that are arranged thus.  The main disadvantage of the diatonic system is that playing in a wide range of keys is impractical. Attempts to overcome this limitation, for example by adding extra rows and more complicated bass systems, invariably add extra bulk and weight, thereby compromising an advantage in striving to overcome a disadvantage. Extreme examples are 18-bass three-row instruments of the type favoured by some French musicians, and B/C/C accordions with 120-button Stradella basses: the size and weight of both these types can be greater than medium-sized piano or chromatic accordions.

A melodeon or diatonic button accordion is a member of the free-reed aerophone family of musical instruments. It is a type of button accordion on which the melody-side keyboard contains one or more rows of buttons, with each row producing the notes of a single diatonic scale. The buttons on the bass-side keyboard are most commonly arranged in pairs, with one button of a pair sounding the fundamental of a chord and the other the corresponding major triad (or, sometimes, a minor triad).

L'accordéon diatonique est un instrument de musique à clavier, utilisant des anches libres, excitées par un vent variable fourni par le soufflet actionné par le musicien. Il désigne les différentes variantes d’accordéon bi-sonore organisées selon une ou plusieurs gammes diatoniques (à la différence de l'accordéon chromatique), même s'il existe des accordéons diatoniques qui ne sont pas bi-sonores comme l'accordéon diatonique russe "(, ou garmon)".


Life cycle.

Warm air has a lower density than cool air, so warmer air rises upwards and cooler air will settle at the bottom (this effect can be seen with a hot air balloon). Clouds form as relatively warmer air, carrying moisture, rises within cooler air. The moist air rises, and, as it does so, it cools and some of the water vapor in that rising air condenses. When the moisture condenses, it releases energy known as latent heat of condensation, which allows the rising packet of air to cool less than the cooler surrounding air continuing the cloud's ascension. If enough instability is present in the atmosphere, this process will continue long enough for cumulonimbus clouds to form and produce lightning and thunder. Meteorological indices such as convective available potential energy (CAPE) and the lifted index can be used to assist in determining potential upward vertical development of clouds. Generally, thunderstorms require three conditions to form:  All thunderstorms, regardless of type, go through three stages: the developing stage, the mature stage, and the dissipation stage. The average thunderstorm has a diameter. Depending on the conditions present in the atmosphere, each of these three stages take an average of 30 minutes.

Developing stage.

The first stage of a thunderstorm is the cumulus stage or developing stage. During this stage, masses of moisture are lifted upwards into the atmosphere. The trigger for this lift can be solar illumination, where the heating of the ground produces thermals, or where two winds converge forcing air upwards, or where winds blow over terrain of increasing elevation. The moisture carried upward cools into liquid drops of water due to lower temperatures at high altitude, which appear as "cumulus" clouds. As the water vapor condenses into liquid, latent heat is released, which warms the air, causing it to become less dense than the surrounding, drier air. The air tends to rise in an "updraft" through the process of convection (hence the term convective precipitation). This process creates a low-pressure zone within and beneath the forming thunderstorm. In a typical thunderstorm, approximately 500 million kilograms of water vapor are lifted into the Earth's atmosphere.

Mature stage.

In the mature stage of a thunderstorm, the warmed air continues to rise until it reaches an area of warmer air and can rise no farther. Often this 'cap' is the tropopause. The air is instead forced to spread out, giving the storm a characteristic anvil shape. The resulting cloud is called "cumulonimbus incus". The water droplets coalesce into larger and heavier droplets and freeze to become ice particles. As these fall, they melt to become rain. If the updraft is strong enough, the droplets are held aloft long enough to become so large that they do not melt completely but fall as hail. While updrafts are still present, the falling rain drags the surrounding air with it, creating "downdrafts" as well. The simultaneous presence of both an updraft and a downdraft marks the mature stage of the storm and produces cumulonimbus clouds. During this stage, considerable internal turbulence can occur, which manifests as strong winds, severe lightning, and even tornadoes.  Typically, if there is little wind shear, the storm will rapidly enter the dissipating stage and 'rain itself out', but, if there is sufficient change in wind speed or direction, the downdraft will be separated from the updraft, and the storm may become a supercell, where the mature stage can sustain itself for several hours.

Dissipating stage.

In the dissipation stage, the thunderstorm is dominated by the downdraft. If atmospheric conditions do not support super cellular development, this stage occurs rather quickly, approximately 20–30 minutes into the life of the thunderstorm. The downdraft will push down out of the thunderstorm, hit the ground and spread out. This phenomenon is known as a downburst. The cool air carried to the ground by the downdraft cuts off the inflow of the thunderstorm, the updraft disappears and the thunderstorm will dissipate. Thunderstorms in an atmosphere with virtually no vertical wind shear weaken as soon as they send out an outflow boundary in all directions, which then quickly cuts off its inflow of relatively warm, moist air, and kills the thunderstorm's further growth. The downdraft hitting the ground creates an outflow boundary. This can cause downbursts, a potential hazardous condition for aircraft to fly through, as a substantial change in wind speed and direction occurs, resulting in a decrease of airspeed and the subsequent reduction in lift for the aircraft. The stronger the outflow boundary is, the stronger the resultant vertical wind shear becomes.

Classification.

There are four main types of thunderstorms: single-cell, multi-cell, squall line (also called multi-cell line) and supercell. Which type forms depends on the instability and relative wind conditions at different layers of the atmosphere ("wind shear"). Single-cell thunderstorms form in environments of low vertical wind shear and last only 20–30 minutes.  Organized thunderstorms and thunderstorm clusters/lines can have longer life cycles as they form in environments of significant vertical wind shear, normally greater than in the lowest of the troposphere, which aids the development of stronger updrafts as well as various forms of severe weather. The supercell is the strongest of the thunderstorms, most commonly associated with large hail, high winds, and tornado formation. Precipitable water values of greater than favor the development of organized thunderstorm complexes. Those with heavy rainfall normally have precipitable water values greater than. Upstream values of CAPE of greater than 800 J/kg are usually required for the development of organized convection.

Single-cell.

This term technically applies to a single thunderstorm with one main updraft. Also known as air-mass thunderstorms, these are the typical summer thunderstorms in many temperate locales. They also occur in the cool unstable air that often follows the passage of a cold front from the sea during winter. Within a cluster of thunderstorms, the term "cell" refers to each separate principal updraft. Thunderstorm cells occasionally form in isolation, as the occurrence of one thunderstorm can develop an outflow boundary that sets up new thunderstorm development. Such storms are rarely severe and are a result of local atmospheric instability; hence the term "air mass thunderstorm". When such storms have a brief period of severe weather associated with them, it is known as a pulse severe storm. Pulse severe storms are poorly organized and occur randomly in time and space, making them difficult to forecast. Single-cell thunderstorms normally last 20–30 minutes.

Multi-cell clusters.

This is the most common type of thunderstorm development. "Mature thunderstorms" are found near the center of the cluster, while dissipating thunderstorms exist on their downwind side. "Multicell storms" form as clusters of storms but may then evolve into one or more squall lines. While each cell of the cluster may only last 20 minutes, the cluster itself may persist for hours at a time. They often arise from convective updrafts in or near mountain ranges and linear weather boundaries, such as strong cold fronts or troughs of low pressure. These type of storms are stronger than the single-cell storm, yet much weaker than the supercell storm. Hazards with the multicell cluster include moderate-sized hail, flash flooding, and weak tornadoes.

Multicell lines.

A squall line is an elongated line of severe thunderstorms that can form along or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front. The squall line contains heavy precipitation, hail, frequent lightning, strong straight line winds, and possibly tornadoes and waterspouts. Severe weather in the form of strong straight-line winds can be expected in areas where the squall line itself is in the shape of a bow echo, within the portion of the line that bows out the most. Tornadoes can be found along waves within a line echo wave pattern, or LEWP, where mesoscale low pressure areas are present. Some bow echoes in the summer are called derechos, and move quite fast through large sections of territory. On the back edge of the rain shield associated with mature squall lines, a wake low can form, which is a mesoscale low pressure area that forms behind the mesoscale high pressure system normally present under the rain canopy, which are sometimes associated with a heat burst. This kind of storm is also known as "Wind of the Stony Lake" (Traditional Chinese:石湖風 – shi2 hu2 feng1, Simplified Chinese: 石湖风) in southern China.

Supercells.

Supercell storms are large, usually severe, quasi-steady-state storms that form in an environment where wind speed or wind direction varies with height ("wind shear"), and they have separate downdrafts and updrafts (i.e., where its associated precipitation is not falling through the updraft) with a strong, rotating updraft (a "mesocyclone"). These storms normally have such powerful updrafts that the top of the supercell storm cloud (or anvil) can break through the troposphere and reach into the lower levels of the stratosphere. Supercell storms can be wide. Research has shown that at least 90 percent of supercells cause severe weather. These storms can produce destructive tornadoes, extremely large hailstones ( diameter), straight-line winds in excess of, and flash floods. In fact, research has shown that most tornadoes occur from this type of thunderstorm. Supercells are generally the strongest type of thunderstorm.

Severe thunderstorms.

In the United States, a thunderstorm is classed as severe if winds reach at least, hail is in diameter or larger, or if funnel clouds or tornadoes are reported. Although a funnel cloud or tornado indicates a severe thunderstorm, a tornado warning is issued in place of a severe thunderstorm warning. A severe thunderstorm warning is issued if a thunderstorm becomes severe, or will soon turn severe. In Canada, a rainfall rate greater than in one hour, or in three hours, is also used to indicate severe thunderstorms. Severe thunderstorms can occur from any type of storm cell. However, multicell, supercell, and squall lines represent the most common forms of thunderstorms that produce severe weather.

Mesoscale convective systems.

A mesoscale convective system (MCS) is a complex of thunderstorms that becomes organized on a scale larger than the individual thunderstorms but smaller than extratropical cyclones, and normally persists for several hours or more. A mesoscale convective system's overall cloud and precipitation pattern may be round or linear in shape, and include weather systems such as tropical cyclones, squall lines, lake-effect snow events, polar lows, and mesoscale convective complexes (MCCs), and they generally form near weather fronts. Most mesoscale convective systems develop overnight and continue their lifespan through the next day. The type that forms during the warm season over land has been noted across North America, Europe, and Asia, with a maximum in activity noted during the late afternoon and evening hours.  Forms of MCS that develop in the tropics are found in use either the Intertropical Convergence Zone or monsoon troughs, generally within the warm season between spring and fall. More intense systems form over land than over water. One exception is that of lake-effect snow bands, which form due to cold air moving across relatively warm bodies of water, and occurs from fall through spring. Polar lows are a second special class of MCS. They form at high latitudes during the cold season. Once the parent MCS dies, later thunderstorm development can occur in connection with its remnant mesoscale convective vortex (MCV). Mesoscale convective systems are important to the United States rainfall climatology over the Great Plains since they bring the region about half of their annual warm season rainfall.

Motion.

The two major ways thunderstorms move are via advection of the wind and propagation along outflow boundaries towards sources of greater heat and moisture. Many thunderstorms move with the mean wind speed through the Earth's troposphere, the lowest of the Earth's atmosphere. Weaker thunderstorms are steered by winds closer to the Earth's surface than stronger thunderstorms, as the weaker thunderstorms are not as tall. Organized, long-lived thunderstorm cells and complexes move at a right angle to the direction of the vertical wind shear vector. If the gust front, or leading edge of the outflow boundary, races ahead of the thunderstorm, its motion will accelerate in tandem. This is more of a factor with thunderstorms with heavy precipitation (HP) than with thunderstorms with low precipitation (LP). When thunderstorms merge, which is most likely when numerous thunderstorms exist in proximity to each other, the motion of the stronger thunderstorm normally dictates the future motion of the merged cell. The stronger the mean wind, the less likely other processes will be involved in storm motion. On weather radar, storms are tracked by using a prominent feature and tracking it from scan to scan.

Back-building thunderstorm.

A back-building thunderstorm, commonly referred to as a training thunderstorm, is a thunderstorm in which new development takes place on the upwind side (usually the west or southwest side in the Northern Hemisphere), such that the storm seems to remain stationary or propagate in a backward direction. Though the storm often appears stationary on radar, or even moving upwind, this is an illusion. The storm is really a multi-cell storm with new, more vigorous cells that form on the upwind side, replacing older cells that continue to drift downwind. When this happens, catastrophic flooding is possible. In Rapid City, South Dakota, in 1972, an unusual alignment of winds at various levels of the atmosphere combined to produce a continuously training set of cells that dropped an enormous quantity of rain upon the same area, resulting in devastating flash flooding. A similar event occurred in Boscastle, England, on 16 August 2004, and over Chennai on 1 December 2015

Hazards.

Each year, many people are killed or seriously injured by severe thunderstorms despite the advance warning. While severe thunderstorms are most common in the spring and summer, they can occur at just about any time of the year.

Cloud-to-ground lightning.

Cloud-to-ground lightning frequently occurs within the phenomena of thunderstorms and have numerous hazards towards landscapes and populations. One of the more significant hazards lightning can pose is the wildfires they are capable of igniting. Under a regime of low precipitation (LP) thunderstorms, where little precipitation is present, rainfall cannot prevent fires from starting when vegetation is dry as lightning produces a concentrated amount of extreme heat. Direct damage caused by lightning strikes occurs on occasion. In areas with a high frequency for cloud-to-ground lightning, like Florida, lightning causes several fatalities per year, most commonly to people working outside.  Acid rain is also a frequent risk produced by lightning. Distilled water has a neutral pH of 7. “Clean” or unpolluted rain has a slightly acidic pH of about 5.2, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid (pH 5.6 in distilled water), but unpolluted rain also contains other chemicals. Nitric oxide present during thunderstorm phenomena, caused by the oxidation of atmospheric nitrogen, can result in the production of acid rain, if nitric oxide forms compounds with the water molecules in precipitation, thus creating acid rain. Acid rain can damage infrastructures containing calcite or certain other solid chemical compounds. In ecosystems, acid rain can dissolve plant tissues of vegetations and increase acidification process in bodies of water and in soil, resulting in deaths of marine and terrestrial organisms.

Hail.

Any thunderstorm that produces hail that reaches the ground is known as a hailstorm. Thunderclouds that are capable of producing hailstones are often seen obtaining green coloration. Hail is more common along mountain ranges because mountains force horizontal winds upwards (known as orographic lifting), thereby intensifying the updrafts within thunderstorms and making hail more likely. One of the more common regions for large hail is across mountainous northern India, which reported one of the highest hail-related death tolls on record in 1888. China also experiences significant hailstorms. Across Europe, Croatia experiences frequent occurrences of hail.  In North America, hail is most common in the area where Colorado, Nebraska, and Wyoming meet, known as "Hail Alley". Hail in this region occurs between the months of March and October during the afternoon and evening hours, with the bulk of the occurrences from May through September. Cheyenne, Wyoming is North America's most hail-prone city with an average of nine to ten hailstorms per season. In South America, areas prone to hail are cities like Bogotá, Colombia.  Hail can cause serious damage, notably to automobiles, aircraft, skylights, glass-roofed structures, livestock, and most commonly, farmers' crops. Hail is one of the most significant thunderstorm hazards to aircraft. When hail stones exceed in diameter, planes can be seriously damaged within seconds. The hailstones accumulating on the ground can also be hazardous to landing aircraft. Wheat, corn, soybeans, and tobacco are the most sensitive crops to hail damage. Hail is one of Canada's most costly hazards. Hailstorms have been the cause of costly and deadly events throughout history. One of the earliest recorded incidents occurred around the 9th century in Roopkund, Uttarakhand, India. The largest hailstone in terms of maximum circumference and length ever recorded in the United States fell in 2003 in Aurora, Nebraska, United States.

Tornadoes and waterspouts.

A tornado is a violent, rotating column of air in contact with both the surface of the earth and a cumulonimbus cloud (otherwise known as a thundercloud) or, in rare cases, the base of a cumulus cloud. Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds between, are approximately across, and travel several kilometers (a few miles) before dissipating. Some attain wind speeds of more than, stretch more than across, and stay on the ground for more than 100 kilometres (dozens of miles).  The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. An EF0 tornado, the weakest category, damages trees but does not cause significant damage to structures. An EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating.  Waterspouts have similar characteristics as tornadoes, characterized by a spiraling funnel-shaped wind current that form over bodies of water, connecting to large cumulonimbus clouds. Waterspouts are generally classified as forms of tornadoes, or more specifically, non-supercelled tornadoes that develop over large bodies of water. These spiralling columns of air frequently develop within tropical areas close to the equator, but are less common within areas of high latitude.

Flash flood.

Flash flooding is the process where a landscape, most notably an urban environment, is subjected to rapid floods. These rapid floods occur more quickly and are more localized than seasonal river flooding or areal flooding and are frequently (though not always) associated with intense rainfall. Flash flooding can frequently occur in slow-moving thunderstorms and is usually caused by the heavy liquid precipitation that accompanies it. Flash floods are most common in densely populated urban environments, where few plants and bodies of water are present to absorb and contain the extra water. Flash flooding can be hazardous to small infrastructure, such as bridges, and weakly constructed buildings. Plants and crops in agricultural areas can be destroyed and devastated by the force of raging water. Automobiles parked within affected areas can also be displaced. Soil erosion can occur as well, exposing risks of landslide phenomena.

Downburst.

Downburst winds can produce numerous hazards to landscapes experiencing thunderstorms. Downburst winds are generally very powerful, and are often mistaken for wind speeds produced by tornadoes, due to the concentrated amount of force exerted by their straight-horizontal characteristic. Downburst winds can be hazardous to unstable, incomplete, or weakly constructed infrastructures and buildings. Agricultural crops, and other plants in nearby environments can be uprooted and damaged. Aircraft engaged in takeoff or landing can crash. Automobiles can be displaced by the force exerted by downburst winds. Downburst winds are usually formed in areas when high pressure air systems of downdrafts begin to sink and displace the air masses below it, due to their higher density. When these downdrafts reach the surface, they spread out and turn into the destructive straight-horizontal winds.

Thunderstorm asthma.

Thunderstorm asthma is the triggering of an asthma attack by environmental conditions directly caused by a local thunderstorm. During a thunderstorm, pollen grains can absorb moisture and then burst into much smaller fragments with these fragments being easily dispersed by wind. While larger pollen grains are usually filtered by hairs in the nose, the smaller pollen fragments are able to pass through and enter the lungs, triggering the asthma attack.

Safety precautions.

Most thunderstorms come and go fairly uneventfully; however, any thunderstorm can become severe, and all thunderstorms, by definition, present the danger of lightning. Thunderstorm preparedness and safety refers to taking steps before, during, and after a thunderstorm to minimize injury and damage.

Preparedness.

Preparedness refers to precautions that should be taken before a thunderstorm. Some preparedness takes the form of general readiness (as a thunderstorm can occur at any time of the day or year). Preparing a family emergency plan, for example, can save valuable time if a storm arises quickly and unexpectedly. Preparing the home by removing dead or rotting limbs and trees, which can be blown over in high winds, can also significantly reduce the risk of property damage and personal injury.  The National Weather Service (NWS) in the United States recommends several precautions that people should take if thunderstorms are likely to occur:

Safety.

While safety and preparedness often overlap, “thunderstorm safety” generally refers to what people should do during and after a storm. The American Red Cross recommends that people follow these precautions if a storm is imminent or in progress:  The NWS stopped recommending the "lightning crouch" in 2008 as it doesn't provide a significant level of protection and will not significantly lower the risk of being killed or injured from a nearby lightning strike.

Frequent occurrences.

Thunderstorms occur throughout the world, even in the polar regions, with the greatest frequency in tropical rainforest areas, where they may occur nearly daily. At any given time approximately 2,000 thunderstorms are occurring on Earth. Kampala and Tororo in Uganda have each been mentioned as the most thunderous places on Earth, a claim also made for Singapore and Bogor on the Indonesian island of Java. Other cities known for frequent storm activity include Darwin, Caracas, Manila and Mumbai. Thunderstorms are associated with the various monsoon seasons around the globe, and they populate the rainbands of tropical cyclones. In temperate regions, they are most frequent in spring and summer, although they can occur along or ahead of cold fronts at any time of year. They may also occur within a cooler air mass following the passage of a cold front over a relatively warmer body of water. Thunderstorms are rare in polar regions because of cold surface temperatures. Some of the most powerful thunderstorms over the United States occur in the Midwest and the Southern states. These storms can produce large hail and powerful tornadoes. Thunderstorms are relatively uncommon along much of the West Coast of the United States, but they occur with greater frequency in the inland areas, particularly the Sacramento and San Joaquin Valleys of California. In spring and summer, they occur nearly daily in certain areas of the Rocky Mountains as part of the North American Monsoon regime. In the Northeast, storms take on similar characteristics and patterns as the Midwest, but with less frequency and severity. During the summer, air-mass thunderstorms are an almost daily occurrence over central and southern parts of Florida.

Energy.

If the quantity of water that is condensed in and subsequently precipitated from a cloud is known, then the total energy of a thunderstorm can be calculated. In a typical thunderstorm, approximately 5×10 kg of water vapor are lifted, and the amount of energy released when this condenses is 10 joules. This is on the same order of magnitude of energy released within a tropical cyclone, and more energy than that released during the atomic bomb blast at Hiroshima, Japan in 1945.  The Fermi Gamma-ray Burst Monitor results show that gamma rays and antimatter particles (positrons) can be generated in powerful thunderstorms. It is suggested that the antimatter positrons are formed in terrestrial gamma-ray flashes (TGF). TGFs are brief bursts occurring inside thunderstorms and associated with lightning. The streams of positrons and electrons collide higher in the atmosphere to generate more gamma rays. About 500 TGFs may occur every day worldwide, but mostly go undetected.

Studies.

In more contemporary times, thunderstorms have taken on the role of a scientific curiosity. Every spring, storm chasers head to the Great Plains of the United States and the Canadian Prairies to explore the scientific aspects of storms and tornadoes through use of videotaping. Radio pulses produced by cosmic rays are being used to study how electric charges develop within thunderstorms. More organized meteorological projects such as VORTEX2 use an array of sensors, such as the Doppler on Wheels, vehicles with mounted automated weather stations, weather balloons, and unmanned aircraft to investigate thunderstorms expected to produce severe weather. Lightning is detected remotely using sensors that detect cloud-to-ground lightning strokes with 95 percent accuracy in detection and within of their point of origin.

Mythology and religion.

Thunderstorms strongly influenced many early civilizations. Greeks believed that they were battles waged by Zeus, who hurled lightning bolts forged by Hephaestus. Some American Indian tribes associated thunderstorms with the Thunderbird, who they believed was a servant of the Great Spirit. The Norse considered thunderstorms to occur when Thor went to fight Jötnar, with the thunder and lightning being the effect of his strikes with the hammer Mjölnir. Hinduism recognizes Indra as the god of rain and thunderstorms. Christian doctrine accepts that fierce storms are the work of God. These ideas were still within the mainstream as late as the 18th century.  Martin Luther was out walking when a thunderstorm began, causing him to pray to God for being saved and promising to become a monk.

Outside of Earth.

Thunderstorms, evidenced by flashes of lightning, on Jupiter have been detected and are associated with clouds where water may exist as both a liquid and ice, suggesting a mechanism similar to that on Earth. (Water is a polar molecule that can carry a charge, so it is capable of creating the charge separation needed to produce lightning). These electrical discharges can be up to a thousand times more powerful than lightning on the Earth. The water clouds can form thunderstorms driven by the heat rising from the interior. The clouds of Venus may also be capable of producing lightning; some observations suggest that the lightning rate is at least half of that on Earth.

A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds, and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.

Un orage (dérivé à l'aide du suffixe "age" de l'ancien français "ore", signifiant « vent ») est une perturbation atmosphérique d'origine convective associée à un type de nuage particulier : le cumulonimbus. Ce dernier est à forte extension verticale, il engendre des pluies fortes à diluviennes, des décharges électriques de foudre accompagnées de tonnerre. Dans des cas extrêmes, l'orage peut produire des chutes de grêle, des vents très violents et, rarement, des tornades.


Typical operation.

For a typical materials science experiment, a sample of the material under study is loaded into the top of the drop tube, which is filled with inert gas or evacuated to create a low-pressure environment. Following any desired preprocessing (e.g. induction heating to melt a metal alloy), the sample is released to fall to the bottom of the tube. During its flight or upon impact the sample can be characterized with instruments such as cameras and pyrometers.  Drop towers are also commonly used in combustion research. For this work, oxygen must be present and the payload may be enclosed in a drag shield to isolate it from high-speed "wind" as the apparatus accelerates toward the bottom of the tower. See a video of a microgravity combustion experiment in the NASA Glenn Five Second Drop Facility at.  Fluid physics experiments and development and testing of space-based hardware can also be conducted using a drop tower. Sometimes, the ground-based research performed with a drop tower serves as a prelude to more ambitious, in-flight investigation; much longer periods of weightlessness can be achieved with parabolic-flight-path aircraft or with space-based laboratories aboard the Space Shuttle or the International Space Station.  The duration of free-fall produced in a drop tube depends on the length of the tube and its degree of internal evacuation. The 105-meter drop tube at Marshall Space Flight Center produces 4.6 seconds of weightlessness when it is fully evacuated. In the drop facility Fallturm Bremen at University of Bremen a catapult can be used to throw the experiment upwards to prolong the weightlessness from 4.74 to nearly 9.3 seconds. Negating the physical space needed for the initial acceleration, this technique doubles the effective period of weightlessness. The NASA Glenn Research Center has a 5 second drop tower (The Zero Gravity Facility) and a 2.2 second drop tower (The 2.2 Second Drop Tower).  Much of the operating cost of a drop tower is due to the need for evacuation of the drop tube, to eliminate the effect of aerodynamic drag. Alternatively the experiment is placed inside an outer box (the drag shield) for which, due to its weight, during its fall the reduction of acceleration due to air drag is less.

Historical uses.

Though the story may be apocryphal, Galileo is popularly thought to have used the Leaning Tower of Pisa as a drop tower to demonstrate that falling bodies accelerate at the same constant rate regardless of their mass.  Drop towers called shot towers were once useful for making lead shot. A short period of weightlessness allows molten lead to solidify into a quasi-perfect sphere by the time it reaches the floor of the tower.  Drop tubes are used for handloading black powder; the drop allows the powder to settle into a case, improving the compression of powder charges.

In physics and materials science, a drop tower or drop tube is a structure used to produce a controlled period of weightlessness for an object under study. Air bags, polystyrene pellets, and magnetic or mechanical brakes are sometimes used to arrest the fall of the experimental payload. In other cases, high-speed impact with a substrate at the bottom of the tower is an intentional part of the experimental protocol.

Une tour d'impesanteur, dans le domaine de l'astronautique, est une installation d'essai permettant de simuler l'impesanteur par la chute libre.