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Perpendicular

Denoting the latest stage of English Gothic church architecture, prevalent from the late 14th to mid 16th centuries and characterized by broad arches, elaborate fan vaulting, and large ...

Atlantic, battle of the

Atlantic, battle of the   Reference library

Marc Milner

The Oxford Companion to World War II

Reference type:
Subject Reference
Current Version:
2003
Subject:
History, Military History, Social sciences, Warfare and Defence
Length:
4,598 words
Illustration(s):
3

...routes converged, targets and good firing positions were difficult for individual submariners to obtain. Dönitz developed a system to solve both the search and the attack problems on the high seas. The search problem was resolved by establishing patrol lines of U-boats perpendicular to the convoy route, controlled by a shore-based plot through high-frequency radio communications . Acting like a huge drift net and manoeuvred on the basis of intelligence, these ‘wolf-packs’ covered a wide area of open ocean. Once in contact with a convoy, shadowers from...

ground cover

ground cover   Quick reference

A Dictionary of Ecology (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...cover The area of ground that is covered by a plant when its canopy edge is projected downwards perpendicularly...

frost creep

frost creep   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...creep The net downslope displacement that occurs when a soil, during a freeze–thaw cycle, expands perpendicular to the ground surface and settles in a nearly vertical direction. http://www.uspermafrost.org/glossary.php The US Permafrost Association...

sea-floor spreading

sea-floor spreading   Quick reference

A Dictionary of Ecology (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...that the ocean floor is created at the spreading (accretionary) plate margins within the ocean basins. Igneous rocks rise along conduits from the mantle , giving rise to volcanic activity in a narrow band along the mid-ocean ridges. The newly formed oceanic crust spreads perpendicularly away from the...

irradiance

irradiance   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...The rate of flow of radiant energy through unit area perpendicular to a solar beam. Total solar irradiance is the dominant driver of global climate ( Mendoza (2005) Advances Space Res. 35, 5 ). See also Mishchenko et al. (2007) Bull. Am. Met. Soc. 88, 5...

crossing the T

crossing the T   Reference library

The Oxford Essential Dictionary of the U.S. Military

Reference type:
Subject Reference
Current Version:
2002

...the T a maneuver in naval tactics in which, with both opposing fleets in column, one fleet succeeds in passing in front of the enemy column and perpendicular to it. In the age of sail and naval gunnery, “crossing the T” gave a decided advantage to the fleet achieving that maneuver in that it was thus able to bring to bear all its guns on the side toward the enemy whereas the enemy ships, being in column, could bring to bear few of their guns, the majority being masked by the friendly ships sailing before them in the...

cover

cover   Quick reference

A Dictionary of Ecology (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...In descriptions of plant communities, the proportion of ground, usually expressed as a percentage, that is occupied by the perpendicular projection down on to it of the aerial parts of individuals of the species under consideration. The most widely used visual scales are the Domin scale and the Braun-Blanquet five-point scale. A more objective estimate may be obtained using a pin-frame or point-quadrat...

Cartesian projection

Cartesian projection   Quick reference

A Dictionary of Ecology (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...projection A mapping technique in which every plane in the area being mapped is projected on to a plane in the map and every line on to a line. Each point in the area under study is identified by three values, representing its location in relation to three mutually perpendicular axes (the Cartesian coordinates of the point). These coordinates are transformed mathematically into a homogeneous set of four coordinates which can then be plotted to produce a graphic representation (a map). The word ‘Cartesian’ is derived from the name of the French...

friction coefficient

friction coefficient   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...coefficient The ratio of the force that maintains contact between an object and a surface and the frictional force that resists the motion of the object; the ratio of two forces acting, respectively, perpendicular and parallel to an interface, between two bodies under relative motion ( Blau (2001) Tribology Int. 34, 9 ). Under the same friction coefficient different normal stresses cause different friction levels ( Kame and Yamashita (2003) Geophys. J. Int. 155, 3 ). In a rockfall, the friction coefficient is the strongest factor in determining...

longshore drift

longshore drift   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...drift The movement of sand and shingle along the coast. Waves usually surge onto a beach at an oblique angle and their swash takes sediment up and along the beach. The backwash usually drains back down the beach at an angle more nearly perpendicular to the coast, taking sediment with it. Thus there is a zigzag movement of sediment along the coast. Longshore currents , initiated by waves, also move beach material along the coast. The term littoral drift is...

Coriolis force

Coriolis force   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...It shows up, for example, in the movement of an air stream, relative to the rotating Earth beneath it. The Coriolis force is proportional to the wind speed U ( z ), and the Coriolis parameter , —where Φ ‎ is the latitude and Ω ‎ is the Earth’s rate of rotation—acts perpendicular to the wind direction ( Orr et al. (2005) Weather 60, 10...

Thiessen polygon

Thiessen polygon   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...polygon A subdivision of a drainage basin, containing a rain gauge. Polygons are constructed by first siting the rain gauges, plotting them on a base map, and connecting the sites by straight lines. The lines are bisected with perpendiculars, which meet to form the polygons. The areas of the polygons are calculated and expressed as fractions of the total area. Each fraction is multiplied by the precipitation recorded by its rain gauge. The sum of these calculations represents total precipitation over the catchment area. For an account, see Yoo et al....

tropics

tropics   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...The Tropic of Cancer lies approximately along latitude 23° 30′ N. Around 21–2 June, the sun’s rays are perpendicular to the ground along this line and the sun exerts its maximum strength in the Northern Hemisphere. Conversely, the sun is overhead at the approximate latitude of 23° 30′ S, the Tropic of Capricorn , on 22–3 December when the sun’s heat is at its maximum in the Southern Hemisphere. Between these two lines of latitude lie the tropics. In America this zone is known as the neotropics and in Africa and South-East Asia as the palaeotropics...

Nun and the Rope to Earth

Nun and the Rope to Earth (Mondari, Mandari/Sudan)   Quick reference

A Dictionary of African Mythology

Reference type:
Subject Reference
Current Version:
2002

...to Earth (Mondari, Mandari/Sudan) Nun is a creator and protector spirit. The cosmos and the world are the work of the creator. The ancestral spirits, Nutu Ko Kak, visit the people from time to time and receive offerings of food. The earth and sky were originally joined by a perpendicular rope, allowing the creator and men to pass at will from the one to the other. In this primordial universe, the lower part, the earth, lacked natural and social diversity. The rope was eventually severed after the sin of fratricide was committed, and earth and the parts...

Seasons

Seasons   Reference library

Encyclopedia of Climate and Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2011
Subject:
Science and technology, Earth Sciences and Geography, Social sciences, Environment
Length:
2,449 words
Illustration(s):
3

...24 hours of daylight, and the Arctic region is in total darkness. The solstice actually occurs when the perpendicular rays of the Sun strike the tropic of Cancer or tropic of Capricorn, respectively. Throughout the rest of the year, the perpendicular rays of the Sun fall at different points between these latitudes. The “figure 8” found on many globes, called an analemma ( Figure 3 ), shows the latitudes of declination where these perpendicular rays strike on each day of the year. On two of these days, the equinoxes , the noonday Sun is directly...

shear

shear   Quick reference

A Dictionary of Geography (5 ed.)

Reference type:
Subject Reference
Current Version:
2015

...exceed soil shear strength ( Simoni et al. (2008) Hydrol. Procs 22, 4 ). Shear stress happens when the applied force acts tangentially to the surface of the body (the down-slope component). It is opposed to a normal stress (the slope-normal component) which is applied perpendicularly. See Namikas (2000) J. Sed. Res. 72, 2 on measuring bed shear stress during aeolian saltation; Sime et al. (2007) Water Resources Res. 43 , W03418 on estimating river bed shear. Within a glacier, the level of shear stress ( τ ‎) experienced at any point is dependent...

Squall Lines

Squall Lines   Reference library

Encyclopedia of Climate and Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2011
Subject:
Science and technology, Earth Sciences and Geography, Social sciences, Environment
Length:
1,254 words
Illustration(s):
2

...rain forms to the rear. The strongest rain and most active convection is usually on the line's most easterly side. Sometimes the line is made up of distinct individual cells; at other times, the pattern is nearly uniform along the line. The flow features that are perpendicular to the leading edge of a squall line are shown in Figure 2 . From the leading edge through the stratiform region (one of light uniform rain), front-to-back flow dominates in the lowest 6 kilometers. The convective region has forward flow above 6 kilometers. A region of weak...

Nancy, Battle of

Nancy, Battle of   Reference library

The Oxford Encyclopedia of Medieval Warfare and Military Technology

Reference type:
Subject Reference
Current Version:
2010

...fight. His army, however, decimated by cold and desertion, by then was probably no larger than two thousand men. Despite this disadvantage, on the morning of 5 January he left his camp, headed southeast, and arrayed his troops in formation along the Jarville stream, which ran perpendicular to the road leading from Nancy to Saint-Nicolas-de-Port. Blocking a narrow passage, the Burgundian line was composed of three corps: the left flank, against the Meurthe; the main division in the center, commanded by the Duke of Burgundy himself; and the right flank, against...

Shear Instability

Shear Instability   Reference library

Encyclopedia of Climate and Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2011
Subject:
Science and technology, Earth Sciences and Geography, Social sciences, Environment
Length:
1,166 words
Illustration(s):
2

...streamlines, resembling a long row of cats' eyes, which is depicted. Thus there are parallel rolls perpendicular to the plane of Figure 1 ; of course, in practice they may be observed from a different direction. The wavelength—the distance between adjacent “eyes”— varies considerably from instance to instance of shear instability in the atmosphere, but is typically in the range of 40 to 100 meters. The rolls usually stretch several wavelengths perpendicular to the plane of flow shown. The whole pattern is carried along by the wind. It grows and may soon...

Orbital Parameters and Equations

Orbital Parameters and Equations   Reference library

Encyclopedia of Climate and Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2011
Subject:
Science and technology, Earth Sciences and Geography, Social sciences, Environment
Length:
3,181 words
Illustration(s):
4

...within the orbit at that time. In the case of a planet moving in an elliptic orbit about the Sun, it is convenient to take a set of rectangular axes in and perpendicular to the plane of reference, with the origin at the center of the Sun. The x -axis may be taken toward the ascending node N , the y -axis being in the plane of reference and 90° from x , while the z -axis is taken to be perpendicular to this reference plane, so that the three axes form a right-handed coordinate system. The reference point from which the angles are measured is γ 0 . As the...

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