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Beer in England

Beer has been brewed in England for thousands of years. As a beer brewing country, it is known for top fermented cask beer (also called real ale) which finishes maturing in the cellar of the pub rather than at the brewery and is served with only natural carbonation.

English beer styles include bitter, mild, brown ale and old ale. Stout, porter and India pale ale were also originally brewed in London. Lager increased in popularity from the mid-20th century. Other modern developments include the consolidation of large brewers into multinational corporations; the growth of beer consumerism; and the expansion of microbreweries and bottle-conditioned beers.

Romano-Celtic Britain
Brewing in what is now England was probably well established when the Romans arrived in 54 BC, and certainly continued under them. In the 1980s, archaeologists found the evidence that Rome's soldiers in Britain sustained themselves on Celtic ale. A series of domestic and military accounts written on wooden tablets were dug up at the Roman fort of Vindolanda, at Chesterholm in modern Northumberland, dating to between AD90 and AD130. They reveal the garrison at Vindolanda buying ceruese, or beer, as the legions doubtless did throughout the rest of Roman Britain, almost certainly from brewers in the local area.

One list of accounts from Vindolanda mentions Atrectus the brewer (Atrectus cervesarius), the first named brewer in British history, as well as the first known professional brewer in Britain. The accounts also show purchases of bracis or braces, that is, emmer wheat (or malt), doubtless for brewing. Quite possibly the garrison bought the malt, and hired a local brewer to make beer from it for the troops. In Roman Britain, brewing, both domestic and retail, must have been widespread: remains indicating the existence of Roman-era malting or brewing operations have been found from Somerset to Northumberland, and South Wales to Colchester. In the third and fourth centuries AD Roman hypocaust technology, for supplying central heating to homes, was adapted in Britain to build permanent corn dryers/maltings, and the remains of these double-floored buildings, with underground flues, are found in Roman towns as well as on Roman farms.

British brewing is generally thought to have been part of a wider Celtic tradition. Since this was well before the introduction of hops, other flavourings such as honey, meadowsweet (Filipendula ulmaria) and mugwort (Artemisia vulgaris) may have been used.

Middle Ages: Ale-wands, ale-wives and ale-conners
Beer was one of the most common drinks during the Middle Ages. It was consumed daily by all social classes in the northern and eastern parts of Europe where grape cultivation was difficult or impossible. Beer provided a considerable amount of the daily calories in the northern regions. In England, the per capita consumption was 275–300 liters (60–66 gallons) a year by the Late Middle Ages, and beer was drunk with every meal.

In the Middle Ages, ale would have been brewed on the premises from which it was sold. Alewives would put out an ale-wand to show when their beer was ready. The mediaeval authorities were more interested in ensuring adequate quality and strength of the beer than discouraging drinking. Gradually, men became involved in brewing and organised themselves into guilds such as the Brewers Guild in London. As brewing became more organised and reliable, many inns and taverns ceased brewing for themselves and bought beer from these early commercial breweries.

An ale-conner, sometimes "aleconner", was an officer appointed yearly at the court-leet of ancient English communities to ensure the goodness and wholesomeness of bread, ale, and beer. There were many different names for this position, which varied from place to place: "ale-tasters", gustatores cervisiae, "ale-founders", and "ale-conners". Ale-conners were often trusted to ensure that the beer was sold at a fair price. Historically, four ale-conners were chosen annually by the Common Hall of the City.

It is sometimes said that: The Ale Conner was a type of early tax-man whose job it was to test the quality and strength of beer, not by quaffing, but by sitting in a puddle of it! They travelled from pub to pub clad in sturdy leather britches. Beer was poured on a wooden bench and the Conner sat in it. Depending on how sticky they felt it to be when they stood up, they were able to assess its alcoholic strength and impose the appropriate duty.

However, the accuracy of the colourful legend is doubtful.

1400–1699: Rise of hopped beer
The use of hops in beer was written of as early as 822 by a Carolingian Abbot. Flavouring beer with hops was known at least as early as the 9th century, but was only gradually adopted because of difficulties in establishing the right proportions of ingredients. Before that, a mix of various herbs called gruit had been used, but did not have the same conserving properties as hops.

In The Book of Margery Kempe, Margery dictates her story to a scribe, and reports that in the early 15th century she attempted to brew beer in Bishop's Lynn, Norfolk, and makes other references to bottles of beer.

In the 15th century, an unhopped beer would have been known as an ale, while the use of hops would make it a beer. Hopped beer was imported to England from the Netherlands as early as 1400 in Winchester, and hops were being planted in England by 1428. At the time, ale and beer brewing were carried out separately, no brewer being allowed to produce both. The Brewers Company of London stated "no hops, herbs, or other like thing be put into any ale or liquore wherof ale shall be made – but only liquor (water), malt, and yeast." This comment is sometimes misquoted as a prohibition on hopped beer. However, hopped beer was opposed by some, e.g. Ale is made of malte and water; and they the which do put any other thynge to ale than is rehersed, except yest, barme, or goddesgood [three words for yeast], doth sophysticat there ale. Ale for an Englysshe man is a naturall drinke. Ale muste haue these properties, it muste be fresshe and cleare, it muste not be ropy, nor smoky, nor it must haue no wefte nor tayle. Ale shulde not be dronke vnder.v.[5] dayes olde .... Barly malte maketh better ale than Oten malte or any other corne doth ... Beere is made of malte, of hoppes, and water; it is a naturall drynke for a doche [Dutch] man, and nowe of late dayes [recently] it is moche vsed in Englande to the detryment of many Englysshe men ... for the drynke is a colde drynke. Yet it doth make a man fatte, and doth inflate the bely, as it doth appere by the doche mennes faces and belyes.

A survey in 1577 of drinking establishment in England and Wales for taxation purposes recorded 14,202 alehouses, 1,631 inns, and 329 taverns, representing one pub for every 187 people.

1700–1899: Industry and empire
The early 18th century saw the development of a popular new style of dark beer in London: porter. Before 1700, London brewers sent out their beer very young and any aging was either performed by the publican or a dealer. Porter was the first beer to be aged at the brewery and despatched in a condition fit to be drunk immediately. It was the first beer that could be made on any large scale, and the London porter brewers, such as Whitbread, Truman, Parsons and Thrale, achieved great success financially.

The large London porter breweries pioneered many technological advances, such as the construction of large storage vats, the use of the thermometer (about 1760), the hydrometer (1770), and attemperators (about 1780).

The 18th century also saw the development of India pale ale. Among the earliest known named brewers whose beers were exported to India was George Hodgson of the Bow Brewery,

The late 18th century saw a system of progressive taxation based on the strength of beer in terms of cost of ingredients, leading to three distinct gradations: "table", "small" and "strong" beer. Mixing these types was used as a way of achieving variation, and sometimes avoiding taxation, and remained popular for more than a century afterwards.

The beer engine (a simple lift-pump), a device for manually pumping beer from a container in a pub's basement or cellar, was invented by Joseph Bramah in 1797. The bar-mounted pump handle, with its changeable pump clip indicating the beer on offer remains a familiar and characteristic sight in most English pubs. Before the beer engine, beer was generally poured into jugs in the cellar or tap room and carried into the serving area.

The Beerhouse Act 1830 enabled anyone to brew and sell beer, ale or cider, whether from a public house or their own homes, upon obtaining a moderately priced licence of just under £2 for beer and ale and £1 for cider, without recourse to obtaining them from justices of the peace, as was previously required. The result was the opening of hundreds of new pubs throughout England, and the reduction of the influence of the large breweries. One of the motivations of the Act was to reduce the abusive over-consumption of gin.

Demand for the export style of pale ale, which had become known as "India pale ale" (IPA), developed in England around 1840. IPA became a popular product in England. Some brewers dropped the term "India" in the late 19th century, but records indicated that these "pale ales" retained the features of earlier IPA.

A pale and well-hopped style of beer was developed in Burton-on-Trent in parallel with the development of India pale ale elsewhere. Previously, Englishmen had drunk mainly stout and porter, but bitter (a development of pale ale) came to predominate. Beers from Burton were considered of a particularly high quality due to synergy between the malt and hops in use and local water chemistry, especially the presence of gypsum. This extensively hopped, lighter beer was easier to store and transport, and so favoured the growth of larger breweries. The switch from pewter tankards to glassware also led drinkers to prefer lighter beers. The development of rail links to Liverpool enabled brewers to export their beer throughout the British Empire. Burton retained absolute dominance in pale ale brewing: at its height one quarter of all beer sold in Britain was produced there until a chemist, C. W. Vincent discovered the process of Burtonisation to reproduce the chemical composition of the water from Burton-upon-Trent, thus giving any brewery the capability to brew pale ale.

In 1880, prime minister William Gladstone's government used the Inland Revenue Act 1880 to replace the long-standing malt tax with a duty on the finished product – beer. As a side effect, homebrewers that produced their own beer for "domestic use" were subject to registration, regulation and inspection, and were required to pay a licence fee. Home brewing was greatly reduced.

In the 19th century, a typical brewery produced three or four mild ales, usually designated by a number of Xs, the weakest being X, the strongest XXXX. They were considerably stronger than the milds of today, with the gravity ranging from around 1.055 to 1.072 (about 5.5% to 7% ABV). Gravities dropped throughout the late 19th century and by 1914 the weakest milds were down to about 1.045, still considerably stronger than modern versions.

Continental lagers began to be offered in pubs in the late 19th century, but remained a small part of the market for many decades.

1900 to 1949: Temperance and war
The temperance movement of the late 19th and early 20th centuries, in combination with First World War emergency measures, introduced a number of changes, such as higher taxation on beer, lower strengths, a ban on "buying a round" and restricted opening hours. Most were gradually repealed over subsequent decades.

The First World War measures had a particularly dramatic effect upon mild ale. As the biggest-selling beer, it suffered the largest cut in gravity when breweries had to limit the average original gravity of their beer to 1.030. In order to be able to produce some stronger beer – which was exempt from price controls and thus more profitable – mild was reduced to 1.025 or lower. English breweries continued to brew a range of bottled, and sometimes draught, stouts until the Second World War and beyond. They were considerably weaker than the pre-war versions (down from 1.055–1.060 to 1.040–1.042) and around the strength that porter had been in 1914. The drinking of porter, with its strength slot now occupied by single stout, steadily declined, and production ceased in the early 1950s. However, Irish-brewed stouts, particularly Guinness, remained firmly popular.

In the early 20th century, serving draught beer from pressurised containers began. Artificial carbonation was introduced in the United Kingdom in 1936, with Watney's experimental pasteurised beer Red Barrel, although this method of serving beer did not take hold in the UK until the late 1960s.

1950 to 1999: Megabreweries and microbreweries
In 1960 almost 40 percent of beer drunk nationally was sold in bottled form, although the figure was 60 percent in the south of England, falling to 20 percent in the North of England. Pale ale had replaced mild as the beer of choice for the majority of drinkers.

Home brewing without a licence was legalised in 1963, and was to become a fairly popular hobby, with homebrewing equipment shops on many high streets. Lager rapidly rose in popularity from the 1970s, increasing from only 2 percent of the market in 1965 to 20 percent in 1975, with English brewers producing their own brands or brewing under licence. Canned beer was also introduced about this time.

A consumer organisation, the Campaign for Real Ale (CAMRA), was founded in 1971 to protect unpressurised beer. The group devised the term real ale to differentiate between beer served from the cask and beer served under pressure and to differentiate both from lager. "Ale" now meant a top-fermented beer, not an unhopped beer. CAMRA was to become an influential force, with a membership of over 170,000.

At the time, brewing was dominated by the "big six" breweries: Whitbread, Scottish and Newcastle, Bass Charrington, Allied Breweries, Courage Imperial and Watneys.

There were also dozens of regional breweries, although the number was dwindling as a result of takeovers, and the microbrewery sector consisted of just four long-standing brewpubs. Most pubs were owned by breweries and only allowed to offer the owning brewery's beers ("the tie"). CAMRA also campaigned against the tendency of smaller brewers to be bought up by larger ones, against short measures, for the preservation of historically significant pubs, and for increased choice and longer opening hours for pubs. CAMRA also produced a Good Beer Guide and campaigned for the preservation of mild ale, which was now seen as an endangered style.

English drinkers became more interested in imported beers during the 1970s and 1980s, partly as a result of increased foreign travel and partly because of promotion of the subject by beer writers such as Michael Jackson, with his 1977 The World Guide to Beer. Newly popular foreign brands included Beck's from Germany, Heineken and Grolsch from the Netherlands, Leffe and Hoegaarden from Belgium, Peroni from Italy, San Miguel from the Philippines, Budweiser and Sierra Nevada from the US and Corona Extra from Mexico. A number of bars specialise in imported beer, with food and decor to match, Belgian and Bavarian themes being the most common.

In 1972, Martin Sykes established Selby Brewery as the first new independent brewing company in England for 50 years. "I foresaw the revival in real ale, and got in early", he said. By the end of the decade he was joined by over 25 new microbreweries, a trend which would only increase in the 1980s. In 1979, Tim Martin opened the first Wetherspoons pub, in Muswell Hill, north London. This was the basis of a national chain of pubs, (over 900 as of 2016) which were to prove influential on the British beer scene, because of their low prices, large premises, and championing of cask ale. Also in 1979 David Bruce established the first "Firkin" brewpub. The Firkin chain consisted of pubs offering cask ale brewed on the premises, or at another brewpub in the chain. The chain expanded to more than 100 pubs over its twenty-year history, considerably adding to the number of brewpubs in England. After a number of changes of ownership, brewing operations were wound up in 2001.

Two pieces of legislation, known as The Beer Orders, were introduced in December 1989, partly in response to CAMRA campaigning. The Orders restricted the number of tied pubs that could be owned by large brewery groups in the United Kingdom to 2,000, and required large brewer landlords to allow a guest ale to be sourced by tenants from someone other than their landlord. The industry responded by spinning off purely pub-owning companies ("pubcos"), such as Punch Taverns and Enterprise Inns, from the older brewing-and-owning companies, notably Allied Lyons, Bass, and Scottish & Newcastle. The Beer Orders were revoked in January 2003, by which time the industry had been transformed.

2000 to present: hops and hipsters

A change to beer taxation, Progressive Beer Duty was introduced by Gordon Brown in 2002. It was a reduction in beer duty based on a brewery's total production and aimed at helping smaller breweries. The legislation had been campaigned for by the Society of Independent Brewers (Siba). In 2009, the combined sales of Siba's 420-plus members increased by 4% compared with 2008. By 2011, the breweries in the UK, were recording an average growth in beer sales of 3% to 7% per annum.

By 2004, the term real ale had been expanded to include bottle-conditioned beer, while the term cask ale had become the accepted global term to indicate a beer not served under pressure.

Interest in imported beer continued to rise, with an influx of Eastern European workers making Lech and Tyskie particularly popular, alongside Staropramen, Budvar and Kozel.

A piece of legislation popularly known as the "twenty four-hour drinking", officially the Licensing Act 2003 came into force in 2005. This removed the previous national restrictions on opening hours, allowing pubs and licensed premises to open for any or all of a twenty four-hour period, subject to agreement with the local licensing authorities. In practice, most pubs made only minor changes to their opening hours.

Although its founding father, Michael Jackson, died in 2007, modern beer writing was burgeoning, with beer columns appearing alongside wine columns in the quality press. Beer writing was to evolve into beer blogging, leaders in both fields including Martyn Cornell, Pete Brown, Roger Protz and Melissa Cole.

In July 2007, a law was introduced to ban smoking in all enclosed public places in England, including pubs. The ban had already been introduced in Scotland the previous year.

The popularity of lager fell from 74.5 per cent in 2008 to 74.3 per cent and the Observer publication suggested that British beer drinkers' "love affair with carbonated beers may finally have peaked". The 2010 edition of the Good Beer Guide showed that there were more than 700 real-ale brewers in the UK at the time of publication — the highest number since the Second World War and four times as many since the founding of Camra. Iain Loe, a spokesman for Camra, explained a preference for moderate alcohol levels and a perception that real ale was healthier as responsible for the shift.

Since the 2010s, there has been what some media outlets describe as an "explosion" of interest in craft beer. Although, the term "craft beer" does not have formal definition in the UK, it is generally taken to mean beer from small breweries which is highly flavourful and distinctive, particularly "hop forward" beers, delivered in bottles or the keykeg draught formats, ideas mainly deriving from the US microbrewery scene. Craft beer may stand alongside other beers in a mainstream pub, or be retailed in specialist outlets, such as the chain owned by Scottish brewers Brewdog. Craft beers are often stronger than standard ales and lagers, and may be sold in $1/3$ pint and $2/3$ pint measures in addition to the usual pints and halves. A number of commentators have noted that craft beer appeals to a younger clientele, particularly those characterised as hipsters. A number of breweries associated with the craft movement have been taken over by multinationals, prompting debate about whether they should still be considered "craft".

Although the choice available to English beer drinkers in the mid-2010s is perhaps unparalleled, there are concerns about the future of pubs, with about 30 closing per week. Bucking the trend somewhat are craft beer outlets, the Wetherspoons chain, and the micropub movement

The Wetherspoons chain has expanded to nearly 900 outlets over its 25-year history, most of them being former shops, banks and so on, rather than traditional pub premises. Describing themselves as freehouses, its branches offer a wider range of cask ales than other pubcos, and they have recently begun offering craft beer. Micropubs are small community pubs with limited opening hours, and focusing strongly on local cask ale.

With cask ale having a secure future, the Campaign for Real Ale has been reconsidering its aims, with the options including focusing on the preservation of pubs.

Levels of alcohol consumption amongst young people in England is significantly lower than previous generations, leading to the rise in popularity of lower-alcohol and alcohol-free beers. Major brewers have introduced alcohol-free varieties of established brands including Guinness and Heineken, and new brands have emerged to cater to the low-alcohol market including Lucky Saint.

Bitter
Bitter is the broad term applied to a well-hopped pale ale, from about 3.5% to 7% in strength and pale gold to dark mahogany in colour. English brewers have several loose names for variations in beer strength, such as best bitter, special bitter, extra special bitter, and premium bitter. There is no agreed and defined difference between an ordinary and a best bitter other than one particular brewery's best bitter will usually be stronger than its ordinary. Two groups of drinkers may mark differently the point at which a best bitter then becomes a premium bitter. Hop levels will vary within each sub group, though there is a tendency for the hops in the session bitter group to be more noticeable. Bitter is dispensed in most formats — hand-pulled from the cask, on draught from the keg, smoothflow or bottled. Drinkers tend to loosely group the beers into:

 * Session or ordinary bitter have strength up to 4.1 per cent ABV. The majority of English beers with the name IPA will be found in this group, such as Greene King IPA, Flowers IPA, Wadworth Henrys Original IPA, etc. These session bitters are not as strong and hoppy as the 18th and 19th century IPAs (or as an India Pale Ale would be in the USA) although IPAs with modest gravities (below 1.040) have been brewed in England since at least the 1920s. This is the most common strength of bitter sold in English pubs, accounting for 16.9 per cent of pub sales.
 * Best bitter have strength between 3.8 per cent and 4.7 per cent ABV. In the United Kingdom, Bitter above 4.2 per cent ABV accounts for just 2.9 per cent of pub sales. The disappearance of weaker bitters from some brewer's rosters means "best" bitter is actually the weakest in the range.
 * Premium bitter have strength of 4.8 per cent ABV and over. Also known as extra special bitter, for instance Fuller's ESB.
 * Golden ale or summer ales were developed in the late 20th century by breweries to compete with the pale lager market. A typical golden ale has an appearance and profile similar to that of a pale lager. Malt character is subdued and the hop profile ranges from spicy to citrus; common hop additions include Styrian Golding and Cascade. Alcohol is in the 4% to 5% range ABV. The style was marketed in 1989 by John Gilbert, a former brewer at Watney in Mortlake, London, who had opened his own operation, the Hop Back Brewery, in Salisbury, England. His aim was to develop a pale ale that could be as refreshing as lager. The result was a drier and hoppier pale ale he called "Summer Lightning", after a novel by PG Wodehouse; it won several awards and inspired numerous imitators.
 * India Pale Ale – although it is often said that India Pale Ale, a strong and well-hopped beer, was designed to "survive the sea voyage to India", modern authorities consider this to be a myth. Twentieth century IPAs were equivalent to a typical bitter, although there has been a tendency to return to 18th century strengths (5.5 per cent upwards), hop rates, e.g. Thornbridge Brewery's Jaipur IPA and Fuller, Smith and Turner's Bengal Lancer, and to emphasise the Indian connection in their branding.

Brown ale
English brown ales range from beers such as Manns Original Brown Ale, which is quite sweet and low in alcohol, to North Eastern brown ale such as Newcastle Brown Ale, Double Maxim and Samuel Smith's Nut Brown Ale.

Mild
Mild in modern times is generally considered to be a low-gravity beer with a low hop rate and predominantly malty palate. Historically, mild ales were of standard strength for the time (and rather strong by modern standards). Modern mild ales are mainly dark coloured with an abv of 3 per cent to 3.6 per cent, though there are lighter hued examples, as well as stronger more traditional examples reaching 6 per cent abv and higher. The term "mild" originally had nothing to do with strength or level of hop bitterness, but rather as a label for beers that were not "vatted" (aged) and hence did not have some of the tart and even slightly sour flavour of ales that were subject to long aging, which was considered a desirable attribute of premium ales. The dark colour characteristic of modern-day milds can come from either the use of roast malt or caramelised sugars, usually both. These ingredients lead to differences in flavour characteristics.

Mild is often thought to be partly a survival of the older style of hop-less brewing (hops were introduced in the 16th century), partly as a cheaper alternative to bitter (for a long time mild was a penny a pot, and bitter beer tuppence), and partly a sustaining but relatively unintoxicating beverage suitable for lunchtime drinking by manual workers. But in reality, mild was probably not hopped differently from other beers of the day, since the term "mild" referred primarily to a lack of the sour tang contributed by age, and not a lack of hop character or alcoholic strength,

Once sold in every pub, mild experienced a catastrophic fall in popularity after the 1960s and was in danger of disappearing from many parts of the United Kingdom. In recent years the explosion of microbreweries has led to a partial recovery, and an increasing number of mild (sometimes labelled 'Dark') brands are now being brewed. Most of these are in the more modern interpretation of "mild"...a sweeter brew with lower alcoholic strength.

Light mild is similar but pale in colour, for instance Harveys Brewery Knots of May. There is some overlap between the weakest styles of bitter and light mild, with the term AK being used to refer to both. The designation of such beers as "bitter" or "mild" has tended to change with fashion. A good example is McMullen's AK, which was re-badged as a bitter after decades as a light mild. AK (a very common beer name in the 19th century) was often referred to as a "mild bitter beer" interpreting "mild" as "unaged". Some breweries have revived the traditional high-gravity strong mild, with alcohol content of 6 per cent or so, the classic example being Sarah Hughes Ruby, brewed to a Victorian recipe.

Burton Ale
Burton Ale is a strong ale, produced in Burton on Trent since at least the 16th century, which is darker and sweeter than bitter. It has sometimes been used as a synonym for old ale.

Old ale
Old ale is a term applied to dark, malty beers above 4.5% ABV, also sometimes called Winter Warmers. Many have "old" in the name, such as Theakston's Old Peculier, Marston's Owd Roger, Robinson's Old Tom. Many brewers make high ABV old ales for bottling, some of which are bottle-conditioned and can mature for several years. Some of these stronger versions are known as barley wine. Stock ale is a strong beer which is used for blending with weaker beers at the brewery and not sold directly. The upper limit on strength for this style is about 11%–12% ABV.

Porter and Stout
Porter is a historically significant style developed in 18th century London, which is the ancestor of stout. English Porters and stouts are generally as dark or darker than old ales, and significantly more bitter. They differ from dark milds and old ales in the use of roast grains, which adds to the bitterness, and lends flavours of toast, biscuit or coffee.

Variations on the style include oatmeal stout, oyster stout, the sweet milk stout, and the very strong imperial stout, all of which are generally available in bottles only. These speciality beers have a tiny proportion of the market, but are of interest to connoisseurs worldwide.

London porter differs from stout in having generally lower gravity and lighter body, closer to bitter. Porter as distinct from stout virtually disappeared during the mid-20th century, but has had a modest revival since the 1980s (e.g. Dark Star Original, Fuller's London Porter).

Archaic styles
Mum, a strong wheat beer with herbal flavouring.

Small beer was a low-strength beer that was consumed throughout the day by all ages. A later survival of small beer were the low-gravity light ale and boys bitter.

Stingo or spingo was strong or old ale. The name may come from the sharp, or "stinging" flavour of a well-matured beer. The Blue Anchor Inn, Helston calls its beers "spingo". The term "stingo" has associations with Yorkshire.

Three threads and Entire. A much repeated story has it that 18th century London drinkers liked to blend aged (up to 18 months) and fresh beers into a mixture known as three threads, and that a certain Ralph Harwood came up with an "entire" beer that reproduced the taste of the mixture in a single brew, and that this "Entire" was the ancestor of porter and stout. However, modern beer scholars tend to doubt the veracity of the story. Nevertheless, a few latter-day Entires are produced (e.g. Old Swan Brewery and Hop Back Brewery).

West Country White Beer, a spontaneously fermented wheat beer.

Wobble was historically a low-strength ale that was provided on site to workers in particularly heavy and thirst-inducing occupations, such as foundries. However, modern-day beers called Wobble tend to be strong.

Lager
Lager is the term generally used in England for bottom-fermented beer.

Despite the traditional English beer being ale, more than half of the current English market is now lager in the Pilsener and Export styles. These lighter coloured, bottom fermented beers first started gaining real popularity in England in the later part of the 20th century.

Carling, from both British and Canadian origin owned by the American/Canadian brewing giant Molson Coors Brewing Company, is the best-selling beer in Britain and is mainly brewed in Burton upon Trent. Meanwhile, the largest brewery in the UK today, Heineken which has three main breweries at (Manchester, Reading and Tadcaster), brews the UK's second-highest selling beer, the lager Foster's.

Other lagers popular in England include Kronenbourg (which also belongs to Carlsberg) and Stella Artois (which belongs to the Belgian brewery InBev and is brewed at Samlesbury near Preston).

Indian cuisine is very popular in England and special lagers such as Cobra Beer have been developed to accompany it.

Temperature
Beer in England is usually served at cellar temperature (between 10 - 14 C), which is often controlled in a modern-day pub, although the temperature can naturally fluctuate with the seasons. Proponents of English beer say that it relies on subtler flavours than that of other nations, and these are brought out by serving it at a temperature that would make other beers seem harsh. Where harsher flavours do exist in beer (most notably in those brewed in Yorkshire), these are traditionally mitigated by serving the beer through a hand pump fitted with a sparkler, a device that mixes air with the beer, therefore aerating and slightly oxidising the beer and softening the flavour while giving the beer an attractive head of foam.

Cask ale and beer
A cask is the traditional method of bulk supply to a pub. The brew is then served from the cask in a cellar via a hand pump, electric pump or by gravity straight from the cask on stillage wherever the cask is kept. Cask conditioned beer is unfiltered and unpasteurized, giving it a limited shelf-life. It lacks artificial carbonation, instead dissolved gas is produced by ongoing fermentation, the gas coming out of solution forming bubbles in the glass. These dispense methods are associated with ale, although there is no technical barrier to serving lager or stout the same way. Most pubs use hand pumps ("beer engines") to draw the beer, whereas stillages are commonly employed at beer festivals. Cask ale and bottle conditioned beer are championed by the Campaign for Real Ale under the name real ale. Prior to stainless steel casks, beer was delivered in wooden barrels, which were lowered to the cellar via a trap-door on the footpath using two ropes wound about the barrels midriff (a parbuckle) to lower the barrel gently down the cellar's ramp. They then had to stand on their sides for a few days so the sediment would settle to the bottom of the belly of the barrel, after which they would be "tapped" by punching the pre-cut centre of the (traditionally cork) bung (at the lower edge of the barrel end) into the barrel by hitting the tapered brass "tap" with a mallet. One could then attach the pipe connector onto the tap, so that the cellarman could turn the tap on when ready. In a similar manner, one would punch through the centre of a bung on the upper side of the barrel's belly with a hardwood spile (tapered peg). The hardwood spile prevents air access. Once the barrel is in use, the spile is replaced with a "soft" spile, traditionally made from softwood, but nowadays from bonded-together (woody) fibres. The soft spile prevents a vacuum forming at the upper surface of the beer: it allows sufficient air in for the beer engine to work, but keeps dust, flies and other mischief-makers out.

Keg ale

Keg beer is a term for beer which is served from a keg, under external carbon dioxide pressure. Keg beer is often filtered or pasteurized, both of which are processes that can render the yeast inactive, increasing the shelf life of the product. However, some believe this is at the expense of flavour.

In the early 20th century, draught beer started to be served from pressurised containers. Artificial carbonation was introduced in the United Kingdom in 1936, with Watney's experimental pasteurised beer Red Barrel. By the early 1970s the term "draught beer" almost exclusively referred to beer served under pressure as opposed to the traditional cask or barrel beer.

The Campaign for Real Ale was founded in 1971 to protect traditional – unpressurised – beer and brewing methods. Keg beer was replacing traditional cask ale in all parts of the UK, primarily because it requires less care to handle. The campaign group devised the term real ale to differentiate between beer served from the cask and beer served under pressure.

Nitrokeg
Nitrokeg dispense is a variation on keg dispense, using a gas mixture emphasising nitrogen instead of carbon dioxide (CO2). It is associated with stouts and Irish "red" ales.

Nitrogen is used under high pressure when dispensing dry stouts (such as Guinness) and other creamy beers because it displaces CO2 to (artificially) form a rich tight head and a less carbonated taste. This makes the beer feel smooth on the palate and gives a foamy appearance. Premixed bottled gas for creamy beers is usually 75 per cent nitrogen and 25 per cent CO2. This premixed gas which only works well with creamy beers is often referred to as Guinness Gas, Beer Gas, or Aligal. Using "Beer Gas" with other beer styles can cause the last 5 per cent to 10 per cent of the beer in each keg to taste very flat and lifeless.

Keykeg
Since the 2000s, a number of brewers and outlets have been introducing a variation on keg dispense. Keykegs deliver the product under gas pressure, but it is internally held in plastic bag, rather like a wine box, so that the gas does not affect the beer. Keykeg beer can also be naturally carbonated, and lightly filtered, removing some of the objections to the older keg format. Nonetheless, it retains much of the advantage in terms of shelf life of the older keg format.

Almost any kind of beer can be delivered in this format, although it tends to be mainly associated with imported, stronger, and speciality beers. The keykeg format is suitable for transporting beer internationally, unlike traditional cask ales, allowing pubs and other outlets to offer a cosmopolitan range. On the other hand, this is a plastic single-use keg. What is, environmentally a major disadvantage.

Sparkler
A sparkler is a device that can be attached to the nozzle of a beer engine. Designed rather like a shower-head, beer dispensed through a sparkler becomes aerated and frothy which results in a noticeable head. Some CO2 is carried into the head, resulting in a softer, sweeter flavour due to the loss of normal CO2 acidity.

There is some dispute about the benefits of a sparkler. There is an argument that the sparkler can reduce the flavour and aroma, especially of the hops, in some beers. The counter argument is that the sparkler takes away harshness. A pub may favour sparklers because the larger head they produce means it does not need to supply as much beer.

Breweries may state whether or not a sparkler is preferred when serving their beers. Generally, breweries in northern England serve their beers with a sparkler attached and breweries in the south without.

Bottled beer
Whilst draught beer takes up the majority of the market, bottled beer has a firm place and is a growing sector. Some brands are sold almost entirely in the bottled format, such as Newcastle Brown Ale and Worthington White Shield. CAMRA promotes bottle-conditioned beer as "real ale in a bottle".

Outlets
The English pub is a national institution. At one time certain pubs, known as alehouses, were allowed to sell only beer. Now most pubs are licensed to sell a range of drinks, with beer making up a significant proportion. The range of beer available in a given establishment can vary from a few mass-market products to a wide selection of cask ales and bottled beers, in a free house. The latter are sometimes called "chalkies" because the current selection of cask ales is often written on a blackboard.

Some on-licensed establishments are considered bars rather than pubs; they are less likely to be free standing, and more likely to be urban in setting and modern in style. "New wave" beer bars tend to specialise in bottled and pressure-dispensed craft beers from around the world, rather than the cask ales of traditional real ale pubs. Some establishments imitate Dutch or Belgian cafés, or German bierkellers as a novelty, with a range of draught and bottled beer to match.

Most off licences (i.e. liquor stores) sell at least a dozen bottled beers. Some specialists sell many more, and may include a few cask ales that can be dispensed to customers in containers to be taken home.

The English do not have a long-standing tradition of beer festivals like the Munich Oktoberfest, but the idea of a "beer exhibition" where a wide variety can be sampled has been enthusiastically taken up since the 1970s. The largest is CAMRA's Great British Beer Festival held every August. Local CAMRA branches organise smaller festivals in most vicinities. Beer festivals often include competitions to judge the best beer.

Historical drinking vessels
A tankard is a form of drinkware consisting of a large, roughly cylindrical, drinking cup with a single handle. Tankards are usually made of silver, pewter, or glass, but can be made of other materials, for example wood, ceramic or leather. A tankard may have a hinged lid, and tankards featuring glass bottoms are also fairly common. Tankards are now rarely used, except those made from glass, but historic tankards are often used as decorative items.

A Toby Jug—also sometimes known as a Fillpot (or Philpot)—is a pottery jug in the form of a seated person, or the head of a recognizable person (often an English king). Typically the seated figure is a heavy-set, jovial man holding a mug of beer in one hand and a pipe of tobacco in the other and wearing 18th century attire: a long coat and a tricorn hat. Like metal tankards, they are now considered decorative items.

A yard of ale or yard glass is a very tall beer glass used for drinking around 2.5 imppt of beer, depending upon the diameter. The glass is approximately 1 yard long, shaped with a bulb at the bottom, and a widening shaft which constitutes most of the height. The glass most likely originated in 17th-century England where the glass was known also as a "Long Glass", a "Cambridge Yard (Glass)" and an "Ell Glass". It is associated by legend with stagecoach drivers, though was mainly used for drinking feats and special toasts. Drinking a yard glass full of beer as quickly as possible is a traditional pub game; the bulb at the bottom of the glass makes it likely that the contestant will be splashed with a sudden rush of beer towards the end of the feat. The fastest drinking of a yard of ale (1.42 litres) in the Guinness Book of Records is five seconds. The former Australian Prime Minister Bob Hawke once held the world record for drinking a yard.

Current beer glasses
Beer is now generally sold in pint and half-pint glasses (Half-pint glasses are generally smaller versions of pint glasses.). The common shapes of pint glass are:

 * Conical glasses are shaped, as the name suggests, as an inverted truncated cone around 6 in tall and tapering by about 1 in in diameter over its height.
 * The nonic, a variation on the conical design, where the glass bulges out a couple of inches from the top; this is partly for improved grip, partly to prevent the glasses from sticking together when stacked, and partly to give strength and stop the rim from becoming chipped or "nicked". The term "nonic" derives from "no nick".
 * Jug glasses, Barrel glasses, or "dimple mugs", are shaped more like a large mug with a handle. They are moulded with a grid pattern of thickened glass on the outside, somewhat resembling the segmentation of a WWII-era hand grenade. The dimples prevent the glass slipping out of the fingers in a washing-up bowl, and the design of the glass emphasises strength, also to withstand frequent manual washing. These design features became less important when manual washing was superseded by machine washing. from the 1960s onwards. Dimpled glasses are now rarer than the other types and are regarded as more traditional. This sort of glass is also known as a "Handle" due to the handle on the glass. They are popular with the older generation and people with restricted movement in their hands which can make holding a usual pint glass difficult.

Ingredients
The most celebrated English hop varieties are Fuggles and Goldings, although commercial pressures may incline brewers to use higher-yielding modern varieties. Modern brewers also sometimes make use of American or Continental hops. South-east England, particularly Kent, is the traditional hop growing area; brewers in the north and west used to economise on the cost of importing hops by producing beers with more of a malt character, a regional distinction that has not entirely vanished. A characteristic technique is dry hopping, where hops are added during the fermentation phase in addition to those that went into the initial boil. Worcestershire and Herefordshire has also been a major hop-growing area. The jargon of the areas is distinguished from that of Kent in certain words. Thus in Kent the drying house is known as an oast-house, in Worcestershire as a kiln, a hop-field is called a hop-garden, in Worcestershire a hop-yard.

Maris Otter is the most celebrated barley used in a brewing malt. Malts can be treated in a number of ways, particularly by degrees of roasting, to obtain different colours and flavours. Oats, wheat malt or unmalted barley may also be included in the mash.

Water—known as "liquor"—is an important ingredient in brewing, and larger breweries often draw supplies from their own wells. Burton upon Trent (see below) is famed for the suitability of its water for brewing, and its mineral balance is often artificially copied.

Top-fermenting yeasts stay on the surface of fermenting beer whilst active, hence top-fermented beers tend to be less naturally clear than lagers and finings are sometimes used to clarify them. Modern breweries carefully maintain their own distinctive strains of yeast.

English brewers are allowed a free hand in the use of adjuncts which can include honey, ginger and spices, although this practice is not common.

Breweries
English brewing is often considered to have a four-tier structure.
 * International megabreweries: Anheuser-Busch InBev, Molson Coors, Heineken, Guinness and Carlsberg
 * National breweries Greene King, Marston's and Wells and Young's. These are "new" nationals, formed by mergers and takeovers of former regional breweries. The old "big six" national breweries (Whitbread, Scottish and Newcastle, Bass Charrington, Allied Breweries, Courage Imperial and Watneys) were all absorbed into international corporations.
 * Regional breweries, often owned and run by successive generations of a family. Elgood's Brewery, Wisbech is an example.
 * Microbreweries and brewpubs, a volatile sector that has undergone considerable expansion in the past 30 years.

Brewpubs
In Britain during the 20th century most of the traditional pubs which brewed their own beer in the brewhouse round the back of the pub, were bought out by larger breweries and ceased brewing on the premises. By the mid-1970s only four brewpubs remained, All Nations, The Old Swan, the Three Tuns and the Blue Anchor.

Brewpubs subsequently resurged, particularly with the rise of the Firkin pub chain, most of whose pubs brewed on the premises, running to over one hundred at peak. However, that chain was sold and eventually its pubs ceased brewing their own beer. The resulting decline in brewpubs was something of a boon to other forms of microbrewing, as it led to an availability of trained craft brewers and brewing equipment.

British brewpubs are not required to double up as restaurants, as is the case in some jurisdictions. Many specialise in ale, whilst others brew continental styles such as lager and wheatbeer. Current examples of small independent brewpubs are The Ministry of Ale, Burnley; The Masons Arms, Headington, Oxford; The Brunswick Inn, Derby; The Watermill pub, Ings, Cumbria; The Old Cannon Brewery, Bury St Edmunds and Fernandes Brewery Tap & Bier Keller, Wakefield.

The tie
After the development of the large London porter breweries in the 18th century, the trend grew for pubs to become tied houses which could only sell beer from one brewery (a pub not tied in this way was called a free house). The usual arrangement for a tied house was that the pub was owned by the brewery but rented out to a private individual (landlord) who ran it as a separate business (even though contracted to buy the beer from the brewery). Another very common arrangement was (and is) for the landlord to own the premises (whether freehold or leasehold) independently of the brewer, but then to take a mortgage loan from a brewery, either to finance the purchase of the pub initially, or to refurbish it, and be required as a term of the loan to observe the solus tie. A growing trend in the late 20th century was for the brewery to run their pubs directly, employing a salaried manager (who perhaps could make extra money by commission, or by selling food).

Most such breweries, such as the regional brewery Shepherd Neame in Kent, which claims brewing lineage back to 1698 and Young's in London, control hundreds of pubs in a particular region of the UK, whilst a few, such as Greene King, are spread nationally. The landlord of a tied pub may be an employee of the brewery—in which case he would be a manager of a managed house, or a self-employed tenant who has entered into a lease agreement with a brewery, a condition of which is the legal obligation (trade tie) only to purchase that brewery's beer. This tied agreement provides tenants with trade premises at a below market rent providing people with a low-cost entry into self-employment. The beer selection is mainly limited to beers brewed by that particular company. A Supply of Beer law, passed in 1989, was aimed at getting tied houses to offer at least one alternative beer, known as a guest beer, from another brewery. This law has now been repealed, but while in force it dramatically altered the industry.

The period since the 1980s saw many breweries absorbed by, or becoming by take-overs, larger companies in the food, hotel or property sectors. The low returns of a pub-owning business led to many breweries selling their pub estates, especially those in cities, often to a new generation of small chains, many of which have now grown considerably and have a national presence. Other pub chains, such as All Bar One and Slug and Lettuce offer youth-orientated atmospheres, often in premises larger than traditional pubs.

A free house is a pub that is free of the control of any one particular brewery. Free houses can, but do not necessarily, serve a varied selection range of guest beers. Some pub chains do so as well.

Burton upon Trent

For centuries, Burton upon Trent has been associated with the brewing industry due to the quality of the local water (from boreholes, not from the River Trent). This comes from the high proportion of dissolved salts in the water, predominantly caused by the gypsum in the surrounding hills; the resulting sulphate brings out the hops—see Burtonisation. Much of the open land within and around the town is protected from chemical treatment to help preserve this water quality.

The town is still home to seven brewers:
 * Coors, a brewery from the United States which produces Carling. In addition to their large-scale plant, Coors also operate the White Shield Brewery, a microbrewery producing a number of speciality beers, including the eponymous Worthington White Shield.
 * Marston, Thompson and Evershed, now Marston's PLC. Marston's also brew Bass beer and Stones Bitter under licence from Anheuser-Busch InBev
 * Burton Bridge Brewery, a small brewery founded in 1982 by Geoff Mumford and Bruce Wilkinson.
 * Tower Brewery, a microbrewery
 * Cottage Brewery, its retail outlet being the nearby Old Cottage Inn
 * Black Hole Brewery, a microbrewery subsidiary of Kammac, a cask supplier

The Bass Museum of Brewing—renamed the Coors Visitor Centre after Coors took over the brewery—continued until June 2008. This was reopened in 2010 as the William Worthington Brewery and its ales—including Worthington Red Shield, White Shield, and "E", are primarily sold through the on-site Brewery Tap outlet.

A by-product of the brewing industry, figuratively and literally, is the Marmite factory in the town: Marmite being made from spent brewer's yeast. Together with the breweries this can give the area a distinctive smell.

A pale and well hopped style of beer was developed in Burton in parallel with the development of India Pale Ale elsewhere. Previously, Englishmen had drunk mainly dark stout and porter beers, but pale ale came to predominate. Burton came to dominate this trade, and at its height one quarter of all beer sold in Britain was produced here. Although over thirty breweries are recorded in 1880, a process of mergers and buy-outs resulted in three main breweries remaining by 1980: Bass, Ind Coopes and Marston's.

The fame of Burton ales gave rise to the English euphemism "gone for a Burton" during World War II, meaning to be missing or have died.

The town's connection with the brewing industry is celebrated by the sculpture of the Burton Cooper in the shopping centre. Burton upon Trent is also known in beer technology circles for the Burton Union recirculating fermenter system, now used only by Marston's Brewery (all other Burton brewers have switched to stainless steel).

Home brewing
Since 1963 it has been legal to brew any amount of beer at home, without a licence, providing it is not sold. Home brewing is a reasonably popular hobby, with many towns having home brew shops. Ale is usually brewed, the required equipment being simpler than that for lager.

Breweriana
Breweriana refers to any article containing a brewery name or brand name, usually in connection to collecting them as a hobby. Examples include beer cans, bottles, openers, tin signs, coasters, beer trays, wooden cases and neon signs.

Advocacy and organisations

 * The British Beer and Pub Association represents large brewers.
 * The Independent Family Brewers of Britain represents regional brewers. It campaigns in favour of the Tie.
 * The Campaign for a Fair Pint are an organisation of publicans campaigning against the Tie.
 * Perfect Pint – website and mobile application allowing users to search and share information about great Real Ales based on personal tastes, location and current pubs availability
 * The Society of Independent Brewers represents small brewers.
 * The Campaign for Real Ale (CAMRA) represents consumers
 * Cask Marque is a voluntary accreditation scheme that allows publicans to display a special symbol indicating that their cask ale is of good quality, as judged by a series of surprise inspections.
 * Real ale's most enthusiastic fans are hobbyists known as tickers or scoopers who try to outdo each other in sampling as many varieties as possible. They are not known to be organised.

title: Beer in England


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Józef Sowiński

Józef Sowiński (1777–1831) was a Polish artillery general and a hero of Poland's November 1830 Uprising.

Life
Józef Longin Sowiński was born on 15 March 1777 in Warsaw. After graduating from the famous Corps of Cadets in Warsaw, he joined the Polish Army as a lieutenant during the 1794 Kościuszko Uprising. After its suppression and the dismemberment of Poland by Russia, Prussia, and Austria, Sowiński's regiment was drafted into the Prussian army. In 1807, he fought at the Battle of Eylau and received the highest Prussian military decoration, the Pour le Mérite. In 1811, after Napoleon Bonaparte proclaimed the Duchy of Warsaw, Sowiński returned to Polish service.

He fought in various battles of the Napoleonic wars. During Napoleon's 1812 invasion of Russia he lost a leg at the Battle of Borodino, near the village of Mozhaysk. He was awarded the Polish Virtuti Militari and the French Legion of Honor. After the Congress of Vienna, he returned to Poland and served as commander of the Warsaw Arsenal of the Army of the Kingdom of Poland. In 1820 he became commandant of the Application School for officers.

After the outbreak of the November Uprising against Russia in 1830, Sowiński became artillery commander of the Warsaw garrison and head of the Government Commission of War (de facto Ministry of War). During the Russian assault on Warsaw on 6 September 1831, Sowiński personally commanded the defense of the Polish capital's western approaches. In what is now its Wola district, he commanded 1,300 men against 11 Russian battalions. His actions have been lauded as heroic.

According to recent historians, he was bayonetted to death by the Russians just after the surrender negotiations, who publicized a story that he had been killed at his post in combat.

Legacy
Sowiński's death was immortalized by Polish poets, including Juliusz Słowacki in Sowiński w okopach Woli (Sowiński in the Wola Trenches). It was also the subject of a painting by Wojciech Kossak and of a ballad by Jacek Kaczmarski. Sowiński was mentioned in reverential terms by Chopin.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Józef Sowiński


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User talk:Marta.Paczynska

Welcome!

Hello, and welcome to Wikipedia. Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers: I hope you enjoy editing here and being a Wikipedian! By the way, you can sign your name on Talk and vote pages using three tildes, like this: ~~~. Four tildes (~~~~) produces your name and the current date. If you have any questions, see the help pages, add a question to the village pump or ask me on my Talk page. Again, welcome! - UtherSRG 15:34, Apr 15, 2005 (UTC)
 * How to edit a page
 * Editing, policy, conduct, and structure tutorial
 * Picture tutorial
 * How to write a great article
 * Naming conventions
 * Manual of Style
 * If you're ready for the complete list of Wikipedia documentation, there's also Topical index.

title: User talk:Marta.Paczynska


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Generic Mapping Tools

Generic Mapping Tools (GMT) are an open-source collection of computer software tools for processing and displaying xy and xyz datasets, including rasterization, filtering and other image processing operations, and various kinds of map projections. The software stores 2-D grids as COARDS-compliant netCDF files and comes with a comprehensive collection of free GIS data, such as coast lines, rivers, political borders and coordinates of other geographic objects. Users convert further data (like satellite imagery and digital elevation models) from other sources and import them. GMT stores the resulting maps and diagrams in PostScript (PS) or Encapsulated PostScript (EPS) format.

Users operate the system from the command line: this enables scripting and the automation of routine tasks. More or less comprehensive graphic user interfaces are available from third parties, as well as web applications, bringing the system's functionality online.

Paul Wessel and Walter  Smith created GMT in the 1980s at Lamont–Doherty Earth Observatory, officially releasing it on October 7, 1991 under the GNU General Public License. The letters GMT originally stood for Gravity, Magnetism and Topography, the three basic types of geophysical data. Besides its strong support for the visualization of geographic data sets, the software includes tools for processing and manipulating multi-dimensional datasets. GMT is most widely used by Earth and Ocean scientists.

title: Generic Mapping Tools


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Wikipedia:Articles for deletion/Elf Only Inn

 This page is an archive of the discussion about the proposed deletion of the article below. This page is no longer live. Further comments should be made on the article's talk page rather than here so that this page is preserved as an historic record. The result of the debate was delete. – ABCD 23:15, 21 Apr 2005 (UTC)

Elf Only Inn
Stub about a webcomic that has been defunct since last august. The article doesn't establish any kind of notability. Radiant_* 15:35, Apr 15, 2005 (UTC)
 * Delete Non-notable, and non-informative anyway. The JPS 18:47, 15 Apr 2005 (UTC)
 * Delete, useless. Grue 20:12, 15 Apr 2005 (UTC)
 * Delete. As I recall, the most noteworthy thing about the comic is that it stopped updating as soon as it was invited to Keenspot. --Carnildo 22:48, 15 Apr 2005 (UTC)
 * Keep. Can be saved, but needs more input.
 * Note: Vote by 72.20.132.7 --Carnildo 20:21, 18 Apr 2005 (UTC)
 * Delete. Useless!! --Neigel von Teighen 20:23, 18 Apr 2005 (UTC)
 * Keep Extravagantly poor article, but this was a pretty popular web-comic in its time.  (Though admittedly not the BEST EVAR.  (Sorry.))  Admittedly no real loss if this particular content is binned.  Alai 04:29, 20 Apr 2005 (UTC)

 * This page is now preserved as an archive of the debate and, like some other VfD subpages, is no longer 'live'. Subsequent comments on the issue, the deletion, or the decision-making process should be placed on the relevant 'live' pages. Please do not edit this page.


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Jesuit Joe

Jesuit Joe is a mysterious character who appears in the eponymous story of Italian comics creator Hugo Pratt. This graphic novel was initially serialised in Pilote magazine before it was released as hardcover albums in 1980, in France entitled Jésuite Joe, and in Italy, entitled L'uomo del grande nord, published by Dargaud and CEPIM, respectively.

In 2017 the graphic novel was published in English under the name The Man From the Great North by IDW Publishing, in an edition where storyboards made by Pratt for the movie mentioned below have been added to the story.

Plot
The laconic, anti-heroic and unpredictable main character, a Canadian native dressed in the uniform of a Sergeant in the Canadian Mounties, travels the wilderness during late 19th or early 20th century Canada, occasionally assisting those he finds in need of help. He rescues a kidnapped child and frees an imprisoned couple, but also shoots a bird for being too happy and stabs a priest in the hand.

The concerns of famed Italian cartoonist Hugo Pratt included responsibility, humanity, and social justice. Skepticism of European ideals in colonial settings is a common theme in his stories and forms the main thrust of Jesuit Joe.

The Jesuit Joe film
Jesuit Joe has been adapted into a film directed by Olivier Austen and starring French actress Laurence Treil.

title: Jesuit Joe


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Battista

Battista is a given name and surname which means Baptist in Italian.

Given named

 * Battista Agnese (died 1564), cartographer from the Republic of Genoa, who worked in the Venetian Republic
 * Battista Dossi, also known as Battista de Luteri, Italian painter
 * Battista Farina (1893-1966), later Battista Pininfarina, Italian automobile designer and the founder of the Carrozzeria Pininfarina.
 * Battista Sforza (1446-1472), Duchess of Urbino and second wife of Federico da Montefeltro

Surnamed

 * Bobbie Battista (1952-2020), American journalist
 * Giovanni Battista, multiple people
 * Miriam Battista (1912-1980), American actress
 * Orlando Aloysius Battista (1917-1995), Canadian chemist and author.

Others

 * Battista, a Disney character who is Scrooge McDuck's butler.
 * Pininfarina Battista, the first car from Automobili Pininfarina

title: Battista


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Paul Spudis

Paul D. Spudis (1952–2018) was an American geologist and lunar scientist. His specialty was the study of volcanism and impact processes on the planets, including Mercury and Mars.

Spudis was well known as a leading advocate of a return to the Moon to use its resources to establish and supply a cislunar space transportation system.

Early life and education
In 1976 he earned a B.S. in geology at the Arizona State University. Following his graduation he spent several months working with Dr. Ronald Greeley at Ames Research Center studying various aspects of Lunar and Martian geology, before transitioning to an internship at the Jet Propulsion Laboratory, during the Mars landing of that year. The following year he went to Brown University to study planetary geology, with a focus on the Moon. A year later he earned his master's degree and moved back to Arizona where he started working for Dr. Greeley who had just joined the faculty at Arizona State University. In 1982 he earned a PhD in geology at the university.

Early career
After graduation, he went to work for the U.S. Geological Survey. In the following years he spent in lunar studies and promoting the idea of lunar exploration. He became a principal investigator at the NASA Office of Space Science, Solar System Exploration Division, planetary geology program. He later joined Lunar and Planetary Institute in Houston as a staff scientist.

Later career
Eventually Spudis joined the Johns Hopkins University Applied Physics Laboratory, and became senior staff scientist. He returned to the Lunar and Planetary Institute in Houston in 2008 and was a senior staff scientist there.

He served as a member of a 1991 White House committee, the Synthesis Group, in Washington D.C. In 1994 he was the deputy leader of the Clementine mission science team. He also served on numerous science advisory committees. At Johns Hopkins’ Applied Physics Laboratory he developed an imaging radar system for the Indian mission to the Moon, Chandrayaan-1. He was a member of the 2004 Presidential Commission on the Implementation of United States Space Exploration Policy. He was a team member of the Mini-RF experiment on NASA's Lunar Reconnaissance Orbiter mission.

Personal life
Spudis was born in Kentucky to Mattie Wren.

He was married to Anne M. Seaborne until his death.

Spudis died on 29 August 2018 of complications from lung cancer.

Honors
In 2016 the American Society of Civil Engineers awarded him the Columbia Medal.

The inner main-belt asteroid 7560 Spudis is named in honor of Paul Spudis.

Spudis, a crater on the Moon, is named after him. This crater is next to the famous Shackleton crater on the south polar region of the Moon, which has been an area of particular interest for future lunar landing missions.

title: Paul Spudis


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Young Guitar Magazine

Young Guitar Magazine is a Japanese guitar magazine first published in May 1969 by Shinko Ongaku Shuppansha (now Shinko Music Entertainment), with a focus on folk music. Starting from the 1970s, it started covering hard rock in the 1970s, and in the 1980s it leaned more towards guitar virtuosos, featuring acts from the heavy metal music and progressive rock genres. The magazine's lead editor was particularly impressed by Van Halen's debut album from 1978, and took that as a sign that bands like it would be the next sensation in rock music.

title: Young Guitar Magazine


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Talk:Jem (singer)

It's Amazing
The page for the single It's Amazing is Incomplete —Preceding unsigned comment added by TeddyDTE (talk • contribs) 14:04, 8 April 2009 (UTC)

Article name
I have several problems with the title of this article. At this point, I would suggest Jem Griffiths or Jem (singer-songwriter) to properly disambiguate her? I know that neither of these is particularly appealing, but I can't think of another way around this. --DropDeadGorgias (talk) 15:40, Apr 15, 2005 (UTC)
 * 1) Disambiguation titles are generally not capitalized, so it should be Jem (singer).
 * 2) Even as Jem (singer), it is not disambiguated enough from Jem (animated), who is also a singer, fictional though she may be.
 * On second thought, I think that the animated Jem was also a songwriter, so that doesn't work either. The general rule of disambiguation titles is to have the most generic term possible that does not encapsulate another article or concept.  Is Jem (live singer) too clunky? --DropDeadGorgias (talk) 15:49, Apr 15, 2005 (UTC)

 * I've just moved this page from Jem Griffiths, on the grounds that she's known as Jem and her real name is Jemma Griffiths, and the hybrid Jem Griffiths is rarely, if ever, used.

 * And the trouble with the capitalization is that there was already a redirect page for Jem (singer) and I didn't know how to erase it so that I could move the existing page to that name. So I compromised.

 * I suspect that a real person should take precedence over a cartoon character, and in any case Jem (animated) refers to the series and not the character. If anyone does an article on the fictional Jem I'd suggest atitle such as Jem (fictional singer) or Jem (animated character).

 * Anyway, I've just spent a lot longer than I thought fixing links, so if anybody decides to move this page again I'll be happy to leave it all up to them!!!

 * Yr obedient (ha!) servant...

 * Lee M 15:54, 15 Apr 2005 (UTC)

 * Well, the issue isn't so much about precedence, but disambiguation titles are supposed to remove ambiguity. Even if the animated singer was at (fictional singer), then the Jem (singer) link would still not properly disambiguate.  Also, the "real person" v. "fictional person" is not enough of a criteria to decide who should get the main article.  I'm not sure what the precedent is so I'll bring it up at Wikipedia talk:Naming conventions. --DropDeadGorgias (talk) 16:11, Apr 15, 2005 (UTC)
 * I feel that DropDeadGorgias is being slightly too pedantic and treating Wikipedia users as if they are stupid. Jem is a singer - that is what she does. The other article is about a fictional character. That's all. Whatever attributes the fictional character has doesn't matter when it comes to changing the article name. Most users can work out the difference. 92.1.178.198 (talk) 11:45, 12 August 2009 (UTC)

Shifted to Jem (singer)
for consistency with other articles... and fixed most of the redirects too. - MykReeve 21:17, 15 Apr 2005 (UTC)

Fair use rationale for Image:JemWishIPt1.jpg
Image:JemWishIPt1.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

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Fair use rationale for Image:Jem - 24.jpg
Image:Jem - 24.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.BetacommandBot 07:24, 5 June 2007 (UTC) i like jem

"Jem was born a long time ago..." ouch, burn!
I've changed it to something less abrasive. :) Musicguyguy (talk) 23:03, 25 March 2010 (UTC)

Biography edit
I've thoroughly researched and edited the biographical content of the article, splitting it into relevant, chronological sections. I hope that content, links and references are all of a high encyclopaedic standard for readers. Cheers :) Atonement1992 14, February 2013 —Preceding undated comment added 00:39, 14 February 2013 (UTC)

24
Am unable to find much firm information online regarding the promotional release of the single "24" - sources conflict in saying it was released in 2003 to promote the album in the US, and others say it was released in 2005 to promote the album in Europe. Due to this lack of any firm references I removed any information on 24 as being a single, it wasn't an official single anyway. However, if anyone can find information on the matter, feel free to include... Cheers, Peter Atonement1992

Assessment comment
Substituted at 19:45, 29 April 2016 (UTC)

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Why is Moby relevant?
In the section, "2004–2006: Finally Woken", the first sentence begins, "After the success of Moby's album Play (1999)..."

This is the first time Moby is mentioned. I keep reading to understand what Moby has to do with anything. Did she sing on the album? Was there an agreement she would wait until his release? Moby's album was released in 1999; this section is 2004-2006.

There should be more information because it's not clear what Moby's 5 year old album has to do with Jem. — Preceding unsigned comment added by Alliwalk (talk • contribs) 15:10, 7 July 2020 (UTC)

title: Talk:Jem (singer)


text:
Wikipedia:Featured article candidates/Khazars/archive1

Khazars
I didn't write the original article, but I substantially re-wrote it (with the help of several dedicated researchers) so I suppose this is a self-nom. Other than Kevin Brook's Khazaria Info Center this article may be the most complete reference on the Khazars available online. --Briangotts 15:40, 15 Apr 2005 (UTC)

 * Comment I haven't read the article yet, but the lead section seems way too short to adequately describe the entire article, especially when you consider the length of the TOC. Is there a suitable image to use for the lead?  The map further down is helpful to those of us who aren't familiar with the region. slambo 15:49, Apr 15, 2005 (UTC)
 * Object. Lots of information there but the structure is horrible seriously needs work. As mentionned above, the lead section is too short, and the table of contents is enourmous. There are several subsections that contain but two or three sentences. Phils 16:20, 15 Apr 2005 (UTC)
 * "Structure needs work" would have gotten your POV across without resorting to hyperbole. Personally I think the extensive TOC helps access the information quicker, and I wish more Wikipedia articles were so painstakingly organized. --Dzimmer6 18:47, 15 Apr 2005 (UTC)
 * Agreed. My apologies to the author. I cannot agree with you about the TOC: although I agree more articles should use subheadings, this TOC is longer than it need be. It is not the length of the TOC per se that bothers me, but the fact that sections like "Byzantine, Georgian and Armenian sources", "Date of the conversion", "Extent of the conversion", which are comprised of 3 or 4 sentences take a place in the TOC. I know whether they deserve this place or not is subjective, but if you look at the way most of our best articles are organized, you'll see such minor items usually do not appear in the TOC. Finally, regarding the structure, what bothers me (apart from the lead, which is definetly too short for a 37kB article)personally is the structure from the "Extent of Influence" section on: there the articles starts to make heavy use of bulleted lists and "keyword lists" instead of flowing text. Once again, I apologizefor responding so crudely to the nomination without explaining my rationale in detail. Phils 21:10, 15 Apr 2005 (UTC)
 * Support. Article is incredibly detailed. --Dzimmer6 18:47, 15 Apr 2005 (UTC)
 * Object. Unfortunately I have to agree with Phils.  Brian has done great work, and the resulting article is scholarly and thorough.  However, it has problems with readability. Definitely needs a longer lead. Could also use some rewriting of awkward sentences and a less choppy structure.  The detail is overwhelming to a casual reader.  Major discussion of primary sources or disagreements between historians is crucial in an academic work, but somewhat distracting in a general reference like Wikipedia.  Sections like Late Historical References could possibly be spun off into separate articles and summarized for the main article. Isomorphic 19:29, 15 Apr 2005 (UTC)
 * I just took a stab at rewriting the intro. Not perfect, but better. Isomorphic 03:22, 17 Apr 2005 (UTC)
 * Support. I don't have a problem with the structure; all the bases are covered in reasonable detail, and logical proceed from one topic to the next. If there seems at times to be a confused amount of data it needs to be remembered that the subject itself is full of gray areas and speculative points. I do agree that the article would be served well by the inclusion of a more images, one especially for a header. Also, I could quibble here and there about spelling or conclusions. But any such objections would be minor nit-picks; basically, it looks good to go for me. -- Obsidian 12:19, 15 Apr 2005 (UTC)
 * Object. Too many red links and also too messy, as the other users have said. Detailed doesn't mean that's a great article. --Neigel von Teighen 21:12, 15 Apr 2005 (UTC)
 * The criteria call for judging this article. The existence, or not, of other articles isn't a criteria. Now if the redlinked article is needed to understand material in this article, that could be a problem, but then this article should be rewritten to add the needed context. The linked article does not necesarily need to be written. - Taxman 21:58, Apr 18, 2005 (UTC)
 * Glorious content, but object for now. Needs a lot of stylistic cleanup, and improved narrative.  Try reading some of the other featured history articles for inspiration and templates to follow.  Some specific to get you started:
 * "Khazars outside of Khazaria" - sections should be paragraphs, not bullet-lists
 * "Debate" - all sections should have an introductory description. In this case, what kind of debate?  debates by whom, when, about what?
 * "Extent of influence" - make these choppy bullet lists into sentences; with connecting phrases.
 * Improve the intro paragraph; make it two, with a better overview. And why is Dmitri Vasil'ev the only person named in the first section?   If he's so important, why doesn't he have an article?  or a link?  or even a bullet in the references section?
 * More references.
 * Clarification of which information comes from what source.  Very important in such a fast-developing and debated field.
 * +sj + 22:26, 15 Apr 2005 (UTC)
 * Support, there will never be "definitive" information about this subject (so the "red line" articles-to-be are understandable.)IZAK 05:05, 17 Apr 2005 (UTC)
 * Object. Bibliography is an ambiguous term that does not make it clear if those resources listed were actually used to add or verify material in the article. Can you either rename the section to 'References' if all those listed were used properly, or split those sources that were into that section and those that were not into a 'Further reading' section or similar. I would also have to echo the request for better flow, especially in the second half of the article. The material appears incredibly well done so I hope these fixes are made and anticipate supporting. - Taxman 18:53, Apr 18, 2005 (UTC)


text:
Dispersion (water waves)

In fluid dynamics, dispersion of water waves generally refers to frequency dispersion, which means that waves of different wavelengths travel at different phase speeds. Water waves, in this context, are waves propagating on the water surface, with gravity and surface tension as the restoring forces. As a result, water with a free surface is generally considered to be a dispersive medium.

For a certain water depth, surface gravity waves – i.e. waves occurring at the air–water interface and gravity as the only force restoring it to flatness – propagate faster with increasing wavelength. On the other hand, for a given (fixed) wavelength, gravity waves in deeper water have a larger phase speed than in shallower water. In contrast with the behavior of gravity waves, capillary waves (i.e. only forced by surface tension) propagate faster for shorter wavelengths.

Besides frequency dispersion, water waves also exhibit amplitude dispersion. This is a nonlinear effect, by which waves of larger amplitude have a different phase speed from small-amplitude waves.

Frequency dispersion for surface gravity waves
This section is about frequency dispersion for waves on a fluid layer forced by gravity, and according to linear theory. For surface tension effects on frequency dispersion, see surface tension effects in Airy wave theory and capillary wave.

Wave propagation and dispersion
The simplest propagating wave of unchanging form is a sine wave. A sine wave with water surface elevation $η(x, t)$ is given by:

 * $$\eta(x,t) = a \sin \left( \theta(x,t) \right),\,$$

where a is the amplitude (in metres) and $θ = θ(x, t$) is the phase function (in radians), depending on the horizontal position (x, in metres) and time (t, in seconds):

 * $$\theta = 2\pi \left( \frac{x}{\lambda} - \frac{t}{T} \right) = k x - \omega t,$$ with  $$k = \frac{2\pi}{\lambda}$$  and  $$\omega = \frac{2\pi}{T},$$

where:
 * λ is the wavelength (in metres),
 * T is the period (in seconds),
 * k is the wavenumber (in radians per metre) and
 * ω is the angular frequency (in radians per second).

Characteristic phases of a water wave are: A certain phase repeats itself after an integer m multiple of 2π: sin(θ) = sin(θ+m•2π).
 * the upward zero-crossing at θ = 0,
 * the wave crest at θ = $1⁄2$ π,
 * the downward zero-crossing at θ = π and
 * the wave trough at θ = $1 1⁄2$ π.

Essential for water waves, and other wave phenomena in physics, is that free propagating waves of non-zero amplitude only exist when the angular frequency ω and wavenumber k (or equivalently the wavelength λ and period T ) satisfy a functional relationship: the frequency dispersion relation

 * $$\omega^2 = \Omega^2(k).\,$$

The dispersion relation has two solutions: ω = +Ω(k) and ω = −Ω(k), corresponding to waves travelling in the positive or negative x–direction. The dispersion relation will in general depend on several other parameters in addition to the wavenumber k. For gravity waves, according to linear theory, these are the acceleration by gravity g and the water depth h. The dispersion relation for these waves is:

$$

an implicit equation with tanh denoting the hyperbolic tangent function.

An initial wave phase θ = θ0 propagates as a function of space and time. Its subsequent position is given by:

 * $$x = \frac{\lambda}{T}\, t + \frac{\lambda}{2\pi}\, \theta_0 = \frac{\omega}{k}\, t + \frac{\theta_0}{k}.$$

This shows that the phase moves with the velocity:

 * $$c_p = \frac{\lambda}{T} = \frac{\omega}{k} = \frac{\Omega(k)}{k},$$

which is called the phase velocity.

Phase velocity
A sinusoidal wave, of small surface-elevation amplitude and with a constant wavelength, propagates with the phase velocity, also called celerity or phase speed. While the phase velocity is a vector and has an associated direction, celerity or phase speed refer only to the magnitude of the phase velocity. According to linear theory for waves forced by gravity, the phase speed depends on the wavelength and the water depth. For a fixed water depth, long waves (with large wavelength) propagate faster than shorter waves.

In the left figure, it can be seen that shallow water waves, with wavelengths λ much larger than the water depth h, travel with the phase velocity

 * $$c_p = \sqrt{gh} \qquad \scriptstyle \text{(shallow water),}\,$$

with g the acceleration by gravity and cp the phase speed. Since this shallow-water phase speed is independent of the wavelength, shallow water waves do not have frequency dispersion.

Using another normalization for the same frequency dispersion relation, the figure on the right shows that for a fixed wavelength λ the phase speed cp increases with increasing water depth. Until, in deep water with water depth h larger than half the wavelength λ (so for h/λ > 0.5), the phase velocity cp is independent of the water depth:

 * $$c_p = \sqrt{\frac{g\lambda}{2\pi}} = \frac{g}{2\pi} T \qquad \scriptstyle \text{(deep water),}$$

with T the wave period (the reciprocal of the frequency f, T=1/f ). So in deep water the phase speed increases with the wavelength, and with the period.

Since the phase speed satisfies $c_{p} = λ/T = λf$, wavelength and period (or frequency) are related. For instance in deep water:

 * $$\lambda = \frac{g}{2\pi}T^2 \qquad \scriptstyle \text{(deep water).}$$

The dispersion characteristics for intermediate depth are given below.

Group velocity
Wave group.gif groups of gravity waves on the surface of deep water. The red square moves with the phase velocity, and the green circles propagate with the group velocity.

Interference of two sinusoidal waves with slightly different wavelengths, but the same amplitude and propagation direction, results in a beat pattern, called a wave group. As can be seen in the animation, the group moves with a group velocity cg different from the phase velocity cp, due to frequency dispersion.

The group velocity is depicted by the red lines (marked B) in the two figures above. In shallow water, the group velocity is equal to the shallow-water phase velocity. This is because shallow water waves are not dispersive. In deep water, the group velocity is equal to half the phase velocity: cg = $\sqrt{gh}$ cp.

The group velocity also turns out to be the energy transport velocity. This is the velocity with which the mean wave energy is transported horizontally in a narrow-band wave field.

In the case of a group velocity different from the phase velocity, a consequence is that the number of waves counted in a wave group is different when counted from a snapshot in space at a certain moment, from when counted in time from the measured surface elevation at a fixed position. Consider a wave group of length Λg and group duration of τg. The group velocity is:

 * $$c_g = \frac{\Lambda_g}{\tau_g}.$$

Wave group space time.svg storm waves as seen from the NOAA M/V Noble Star, Winter 1989.]] The number of waves in a wave group, measured in space at a certain moment is: Λg / λ. While measured at a fixed location in time, the number of waves in a group is: τg / T. So the ratio of the number of waves measured in space to those measured in time is:

\tfrac{\text{No. of waves in space}}{\text{No. of waves in time}} = \frac{\Lambda_g / \lambda}{\tau_g / T} = \frac{\Lambda_g}{\tau_g} \cdot \frac{T}{\lambda} = \frac{c_g}{c_p}. $$

So in deep water, with cg = $\sqrt{gh}$ cp, a wave group has twice as many waves in time as it has in space.

The water surface elevation η(x,t), as a function of horizontal position x and time t, for a bichromatic wave group of full modulation can be mathematically formulated as:

\eta = a\, \sin \left( k_1 x - \omega_1 t \right) + a\, \sin \left( k_2 x - \omega_2 t \right), $$ with:
 * a the wave amplitude of each frequency component in metres,
 * k1 and k2 the wave number of each wave component, in radians per metre, and
 * ω1 and ω2 the angular frequency of each wave component, in radians per second.

Both ω1 and k1, as well as ω2 and k2, have to satisfy the dispersion relation:

 * $$\omega_1^2 = \Omega^2(k_1)\,$$ and  $$\omega_2^2 = \Omega^2(k_2).\,$$

Using trigonometric identities, the surface elevation is written as:

\eta= \left[ 2\, a\, \cos \left( \frac{k_1 - k_2}{2} x - \frac{\omega_1 - \omega_2}{2} t \right) \right]\; \cdot\; \sin \left( \frac{k_1 + k_2}{2} x - \frac{\omega_1 + \omega_2}{2} t \right). $$

The part between square brackets is the slowly varying amplitude of the group, with group wave number $\sqrt{gλ / (2π)}$ ( k1 − k2 ) and group angular frequency $\sqrt{gh}$ ( ω1 − ω2 ). As a result, the group velocity is, for the limit k1 → k2 :

 * $$c_g = \lim_{k_1\, \to\, k_2} \frac{\omega_1 - \omega_2}{k_1 - k_2}

= \lim_{k_1\, \to\, k_2} \frac{\Omega(k_1) - \Omega(k_2)}{k_1 - k_2} = \frac{\text{d}\Omega(k)}{\text{d}k}.$$

Wave groups can only be discerned in case of a narrow-banded signal, with the wave-number difference k1 − k2 small compared to the mean wave number $1⁄2$ (k1 + k2).

Multi-component wave patterns
Wave disp.gif on deep water. The superposition (dark blue line) of three sinusoidal wave components (light blue lines) is shown. The effect of frequency dispersion is that the waves travel as a function of wavelength, so that spatial and temporal phase properties of the propagating wave are constantly changing. For example, under the action of gravity, water waves with a longer wavelength travel faster than those with a shorter wavelength.

While two superimposed sinusoidal waves, called a bichromatic wave, have an envelope which travels unchanged, three or more sinusoidal wave components result in a changing pattern of the waves and their envelope. A sea state – that is: real waves on the sea or ocean – can be described as a superposition of many sinusoidal waves with different wavelengths, amplitudes, initial phases and propagation directions. Each of these components travels with its own phase velocity, in accordance with the dispersion relation. The statistics of such a surface can be described by its power spectrum.

Dispersion relation
In the table below, the dispersion relation ω2 = [Ω(k)]2 between angular frequency ω = 2π / T and wave number k = 2π / λ is given, as well as the phase and group speeds.

Deep water corresponds with water depths larger than half the wavelength, which is the common situation in the ocean. In deep water, longer period waves propagate faster and transport their energy faster. The deep-water group velocity is half the phase velocity. In shallow water, for wavelengths larger than twenty times the water depth, as found quite often near the coast, the group velocity is equal to the phase velocity.

History
The full linear dispersion relation was first found by Pierre-Simon Laplace, although there were some errors in his solution for the linear wave problem. The complete theory for linear water waves, including dispersion, was derived by George Biddell Airy and published in about 1840. A similar equation was also found by Philip Kelland at around the same time (but making some mistakes in his derivation of the wave theory).

The shallow water (with small h / λ) limit, ω2 = gh k2, was derived by Joseph Louis Lagrange.

Surface tension effects
In case of gravity–capillary waves, where surface tension affects the waves, the dispersion relation becomes:

\omega^2 = \left( g k + \frac{\sigma}{\rho} k^3 \right) \tanh (kh), $$ with σ the surface tension (in N/m).

For a water–air interface (with and ) the waves can be approximated as pure capillary waves – dominated by surface-tension effects – for wavelengths less than 0.4 cm. For wavelengths above 7 cm the waves are to good approximation pure surface gravity waves with very little surface-tension effects.

Interfacial waves

For two homogeneous layers of fluids, of mean thickness h below the interface and  above – under the action of gravity and bounded above and below by horizontal rigid walls – the dispersion relationship ω2 = Ω2(k) for gravity waves is provided by:

\Omega^2(k) = \frac{g\, k (\rho - \rho')}{\rho\, \coth( k h ) + \rho'\, \coth( k h')}, $$

where again ρ and  are the densities below and above the interface, while coth is the hyperbolic cotangent function. For the case  is zero this reduces to the dispersion relation of surface gravity waves on water of finite depth h.

When the depth of the two fluid layers becomes very large (h→∞, →∞), the hyperbolic cotangents in the above formula approaches the value of one. Then:

\Omega^2(k) = \frac{\rho - \rho'}{\rho + \rho'}\, g\, k. $$

Shallow water
Amplitude dispersion effects appear for instance in the solitary wave: a single hump of water traveling with constant velocity in shallow water with a horizontal bed. Note that solitary waves are near-solitons, but not exactly – after the interaction of two (colliding or overtaking) solitary waves, they have changed a bit in amplitude and an oscillatory residual is left behind. The single soliton solution of the Korteweg–de Vries equation, of wave height H in water depth h far away from the wave crest, travels with the velocity:

 * $$c_p = c_g = \sqrt{g(h+H)}.$$

So for this nonlinear gravity wave it is the total water depth under the wave crest that determines the speed, with higher waves traveling faster than lower waves. Note that solitary wave solutions only exist for positive values of H, solitary gravity waves of depression do not exist.

Deep water
The linear dispersion relation – unaffected by wave amplitude – is for nonlinear waves also correct at the second order of the perturbation theory expansion, with the orders in terms of the wave steepness k a (where a is wave amplitude). To the third order, and for deep water, the dispersion relation is

 * $$ \omega^2 = gk \left[1+(ka)^2\right],$$ so  $$c_p = \sqrt{\frac{g}{k}}\, \left[ 1 + \tfrac12\, (ka)^2 \right] + \mathcal{O}\left((ka)^4\right).$$

This implies that large waves travel faster than small ones of the same frequency. This is only noticeable when the wave steepness k a is large.

Waves on a mean current: Doppler shift
Water waves on a mean flow (so a wave in a moving medium) experience a Doppler shift. Suppose the dispersion relation for a non-moving medium is:

 * $$\omega^2 = \Omega^2(k),\,$$

with k the wavenumber. Then for a medium with mean velocity vector V, the dispersion relationship with Doppler shift becomes:

 * $$\left( \omega - \mathbf k \cdot \mathbf V \right)^2 = \Omega^2(k),$$

where k is the wavenumber vector, related to k as: k = |k|. The dot product k•V is equal to: k•V = kV cos α, with V the length of the mean velocity vector V: V = |V|. And α the angle between the wave propagation direction and the mean flow direction. For waves and current in the same direction, k•V=kV.

Other articles on dispersion

 * Dispersive partial differential equation
 * Capillary wave

Dispersive water-wave models

 * Airy wave theory
 * Benjamin–Bona–Mahony equation
 * Boussinesq approximation (water waves)
 * Cnoidal wave
 * Camassa–Holm equation
 * Davey–Stewartson equation
 * Kadomtsev–Petviashvili equation (also known as KP equation)
 * Korteweg–de Vries equation (also known as KdV equation)
 * Luke's variational principle
 * Nonlinear Schrödinger equation
 * Shallow water equations
 * Stokes' wave theory
 * Trochoidal wave
 * Wave turbulence
 * Whitham equation

title: Dispersion (water waves)