Dome (pronounced dohm)
(1) In
architecture, a vault, having a circular plan and usually in the form of a
portion of a sphere, so constructed as to exert an equal thrust in all
directions.
(2) A
domical roof or ceiling; a polygonal vault, ceiling, or roof.
(3) Any
covering thought to resemble the hemispherical vault of a building or room; anything
shaped like a hemisphere or inverted bowl.
(4) In
water management, (usually in dam design), a semidome having its convex surface
toward the impounded water.
(5) In
crystallography, a form having planes that intersect the vertical axis and are
parallel to one of the lateral axes.
(6) In
geology, an upwarp (a broad anticline (a fold with strata sloping downwards on
each side) caused by local uplift).
(7) In
geology, a mountain peak having a rounded summit (a structure in which rock layers
slope away in all directions from a central point).
(8) As vistadome,
in passenger vehicles (usually railroad cars), a raised, glass-enclosed section
of the roof of, placed over an elevated section of seats to afford passengers a
full view of scenery (not usually truly in the hemispherical shape of a dome).
(9) In
horology, the inner cover for the works of a watch which snaps into the rim of
the case.
(10) A
building; a house; an edifice (obsolete except as a literary device).
(11) As
heat dome, a meteorological phenomenon in which the interplay of high & low
pressure atmospheric systems interact to produce static, warm air over a large
area.
(12) To
cover with or as if with a dome; to shape like a dome.
(13) To
rise or swell as a dome.
(14) In
slang, a person's head (the form chrome dome used of the bald).
(15) In
slang (both military and in some criminal classes), to shoot in the head (often
in the form “got domed”).
(16) In
African-American slang, to perform fellatio upon.
1505–1515:
From the Middle French domme & dome (a town-house; a dome, a cupola) (which
persists in modern French as dôme), from
the Provençal doma, from the Italian duomo (cathedral), from the Medieval
Latin domus (ecclesiae; literally “house (of the church)”), a calque of the Ancient
Greek οἶκος τῆς ἐκκλησίας
(oîkos tês ekklēsías). Dome is a noun & verb, domed & doming
are verbs and domelike, domical, domish & domesque are adjectives; the noun
plural is domes.
By the
1650s, the formalized use in architecture ensured the meaning was (more or
less) standardized as “a round, vaulted roof, a hemispherical covering of a
building” and thus the ultimate specialized evolution from the Greek dōma (a house, housetop (used especially
of those with a roof “in the eastern style”), from domos (house), from the primitive Indo-European root dem- (house, household). The medieval use of the German dom and Italian duomo as verbal shorthand for “cathedral” (essentially a clipping
from “house of God”) was picked up in the imperfect way so many words entered
English to describe architectural features in the style of hemispherical cupolas,
the domes at the intersection of the nave and the transept, or over the
sanctuary, characteristic architectural feature of Italian cathedrals. The sense in English of “a building, a house”
had been borrowed in English as early as the 1510s and was used mostly of
stately homes and it endures but only as a literary device and it’s rarely seen
outside of poetry.
The
shape occurs to one degree or another in nature and is common in man-made
objects and the built environment so dome is an often seen modifier (cake dome,
pleasure dome, lava dome; onion dome et al) and appears in the opening lines of
one of the most cherished fragments of English verse: Kubla Khan (1797) by
Samuel Taylor Coleridge (1772-1834).
In Xanadu did Kubla Khan
A stately pleasure-dome decree:
Where Alph, the sacred river, ran
Through caverns measureless to man
Down to a sunless sea.
Some of
the use has also been opportunistic and not especially domical. Vistadomes were raised, glass-enclosed
sections built into the roofs of railway carriages, placed over an elevated
section of seats to afford passengers a better view of the scenery. The idea was picked up by General Motors, the
Oldsmobile Vista Cruiser station wagon (1964-1977), the Buick Roadmaster Estate
(1991-1996) and the Scenicruiser busses (1954-1956 and made famous in the Greyhound
livery some wore until the 1970s) all used raised, partially-windowed sections
although none were officially described as “domes”.
The Hagia Sophia, now the main mosque in Istanbul; the minarets were added after the fall of Constantinople to the Ottoman Turks in 1453 and there are many architectural critics who maintain visually they improve the balance of the structure. The illustration on the right shows how the Byzantine engineers used pendentives to make the construction of domes possible.
Domes
however are most associated with grand-scale, representational architecture
(although quite a few builders of McMansions found them hard to resist). One intriguing aspect of structural
engineering upon which the integrity of a dome depends on what are called pendentives
(the triangular segments of the lower part of a hemispherical dome left by the
penetration of the dome by two semicircular vaults intersection at right angles). Dating from 1727, pendentive was from the
mid-sixteenth century French pendentif,
from the Latin pendentem (nominative pendens) (hanging and the source of the
English “pendulous”), the present participle of pendere (to hang) from the primitive Indo-European roots pen & spen-
(to draw, stretch, spin). What pendentives
permit is the use of a circular dome over a square void square room or an
elliptical one over something rectangular room.
Pendentives, (geometrically the triangular segments of a sphere), taper
to points at the bottom and spread at the top to establish the continuous
circular or elliptical base as required.
As structural supports, pendentives distribute the bulk of a dome’s
weight to the four corners (the strongest points) and ultimately to the piers and
the foundations below. The classic
example is the Hagia Sophia, the sixth century Byzantine cathedral at Constantinople
(modern day Istanbul). It was converted
into a mosque when Constantinople fell to the Ottoman Turks in 1453 and, after
a century-odd as a museum, is again a mosque.
Scale model of Germania. Hitler would spend hours pondering the details but in 1945, he spent even longer looking at the model of what was planned for the Austrian city of Linz where he'd decided to have his tomb installed.
Domes
have long been a favorite of emperors, dictators and those other megalomaniacs:
architects. A truly monumental one would
have been the Volkshalle (People's
Hall and known also as the Große Halle
(Great Hall) & Ruhmeshalle (Hall
of Glory), the centerpiece of Adolf Hitler’s (1889-1945; Führer (leader) and
German head of government 1933-1945 & head of state 1934-1945) never
realized plan to re-built Berlin as Germania, a worthy Welthauptstadt (world capital) of his “thousand year Reich”. Although Albert Speer (1905–1981; Nazi court
architect 1934-1942; Nazi minister of armaments and war production 1942-1945) was
Germania’s chief architect, in some aspects he was really a glorified
draftsman, correcting the technical errors in the drawings passed to him by the
Führer who had be sketching parts of the design since the early 1920s.
Even by
the standards of the super-dimensionality which was characteristic of the Third
Reich, the domed hall would have been extraordinary. The oculus would have been 46 m (151 feet) in
diameter which would have accommodated the entire rotunda of Hadrian's Pantheon
and the dome of St Peter's Basilica. The 250 m (820 feet) diameter of the dome was
(and this was a signature of Speer’s approach), bigger even than Hitler had
requested and he was much displeased to learn of a rival architect’s plans for
a dome 15 m (49 feet) greater in diameter to sit atop the city’s new railway
station. As things turned out, none of
the grandiose structures were ever built and although a tinge of regret can be
found in Speer’s post-war thoughts, even he admitted the designs were a failure
because of “their lack of human scale”.
Berlin's rebuilt Reichstag with steel & glass dome.Berlin
did however eventually get a new dome, albeit it one rendered not in granite
but the glass and steel the Führer thought was fine for factories and
warehouses but which would have appalled him as a method of construction for
public, representational architecture.
Plonked atop the rebuilt Reichstag, it was said to symbolize the
reunification of Germany although quite how it managed that has never really
been explained although the distinctive structure has become a city landmark
and people seem to like it. A clever
design, it sits directly above the chamber of the Bundestag (the lower house of
the bicameral federal parliament) and permits public observation, the clever
design also reducing energy use by optimizing the input of natural light while
moving shrouds minimize glare and heat-soak.
Cinerama Dome, Los Angeles in 1965, the year of its greatest commercial success.
The
Cinerama Dome movie theatre sits on Hollywood’s Sunset Boulevard. Opened in 1963, the Cinerama Dome introduced
a new concept for film projection, a curved screen which sat inside a geodesic
dome based on the design developed by US systems theorist & architect
Richard Buckminster Fuller (1895–1983), one attraction of which was such things
could be built at lower coast and in much less time than a conventional theatre
building. Intended to be the first of
perhaps thousands around the planet, it was built in a still remarkable four months
but it remains the only concrete geodesic on the planet and while it has
operated intermittently since being closed during the COVID-19 pandemic, its future
is uncertain and although it will probably be preserved as a historic building,
it’s likely to be re-purposed as retail or restaurant space.
Lindsay Lohan at the Scary Movie V premiere, Cinerama Dome, April 2013.
The end
of the line for Cinerama is another marker in the evolution of the technology
which underpinned the evolution of the US economy from one based on agriculture,
to one increasingly industrial to one geared around the military & entertainment. In the 1950s, cinema’s greatest challenge
came from television and the film studios fought back by creating differentiation
in their products. The venture into 3D
proved a cul-de-sac for a number of reasons but one thing cinemas could do was make
their big screens huge and during the 1950s the wide-screen Cinemascope enjoyed
a boom. However, there was a limit to
how much screens could grow, hence the interest in Cinerama which projected
onto a curved screen designed to take advantage of the way the human eye sees
and processes images, the system at its best when provided by three synchronized
projectors. The idea lives on in the
curved screens which have become popular among gaming freaks who enjoy the
sense of “envelopment”. It was also the
era during which populations moved further from city centres into suburbs and
thus, cinemas also needed to move, more of which (but often smaller) would be
required. Thus the attraction of the geodesic
dome came which, largely pre-fabricated, was cheap to produce and quick to
assemble. However, Cinerama was expensive
to film, to print, to produce and the sheer size and weight of the prints meant
it was costly even to ship the material to venues and the conversion process to
something which could be used with conventional projection.
Heat
Domes
July 2023 Global
heat map from the Climate Change Institute, University of Maine, USA. For those unconvinced, Fox News continues to
provide alternative facts.
The “heat
dome” is a weather phenomenon, the physics of which has for decades been
understood but of late the term has entered general use as much of the northern
hemisphere has suffered from prolonged, unusually high temperatures, July 2023
measured as the hottest month ever recorded.
A heat dome occurs when a large, high-pressure system traps and
concentrates hot air in a specific region, leading to prolonged and extremely
high temperatures. Under a heat dome, the atmospheric pressure aloft prevents
the hot air from rising and dissipating, effectively acting as a lid or cap
over the area, thus the image of a dome sitting over the land.
The UK's Royal Meteorological Service's simple illustration of the physics of a heat dome. Heat
domes are also their own feedback loop.
A static areas of high pressure which already contains warm or hot air
trapped under the high will become hotter and hotter, creating a heat dome. Hot air will rise into the atmosphere, but
high pressure acts as a lid and causes the air to subside or sink; as the air
sinks, it warms by compression, and the heat builds. The ground also warms,
losing moisture and making it easier to heat even more.
