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Overview

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 ...

Plate Tectonics

Plate Tectonics   Reference library

Encyclopedia of Global Change

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Environmental Science, Social sciences, Environment
Length:
6,065 words
Illustration(s):
5

...plates. There is a small plate to the west of North America and north of 40° north latitude called the Juan de Fuca plate. The Philippine plate is split up by the edges of the map. The jagged pattern of the midoceanic ridges is caused by alternating ridge crests (usually perpendicular to the relative plate motion) and transform faults (parallel to relative plate motion). The East African Rift Valley (not shown) is sometimes considered as a plate boundary separating the Nubian plate (to the west) from the Somalian plate (to the east). The black arrows show...

Renewable Energy Sources

Renewable Energy Sources   Reference library

Encyclopedia of Global Change

Reference type:
Subject Reference
Current Version:
2005

...which is usually water or air. Flat-plate collectors can receive both direct and diffuse solar energy. Insulation, selective coatings, and transparent cover sheets can be used to boost the collector's performance, as can tilting of the collector to be as close as possible to perpendicular to the Sun's direct radiation. Flat-plate collectors are limited in terms of the intensity of heat energy that they can deliver. In general, flat-plate collectors can produce heat energy of temperatures up to approximately 80°C. To produce higher working temperatures, it is...

Sea Ice

Sea Ice   Reference library

Encyclopedia of Global Change

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Environmental Science, Social sciences, Environment
Length:
4,223 words
Illustration(s):
5

...on this planet, is due to the open crystalline structure of ice: the form found under ordinary conditions has a hexagonal structure, with oxygen atoms forming parallel sheets of puckered hexagons, like a deformed beehive. The principal axis, or c-axis, of the unit cell lies perpendicular to the plane of the sheet, which forms the basal plane. When an ice crystal grows, it is energetically easier for new molecules to join an existing sheet than to begin a new sheet. Ice crystals therefore grow more readily along the a- and b-axes (axes in the basal plane) than...

aspect

aspect   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...The direction in which sloping ground faces. Technically, it is the compass direction (or azimuth ) indicated by a line perpendicular to the steepest...

along-track scanning radiometer

along-track scanning radiometer   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...scanning radiometer ( ATSR ) A radiometer that scans parallel to the ground track of a polar-orbiting satellite , often in a fixed direction, perpendicular to the surface, i.e. looking towards the nadir...

pressure-plate anemometer

pressure-plate anemometer   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...anemometer An anemometer that determines wind speed from the force exerted by the wind on a solid plate. The basic principle is ancient, a swinging-plate anemometer having been described by Leonardo da Vinci . A later form maintained the plate perpendicular to the wind. See drag-force anemometer...

billows

billows   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...1 Approximately parallel bands of cloud that lie perpendicular to the wind direction, with relatively narrow spaces between them. Compare corrugations . 2 A form of noctilucent cloud (classified as Type III) consisting of approximately parallel, regularly spaced streaks of cloud. Sometimes observed in combination with bands (2) , and often exhibiting relatively rapid changes over a period of several minutes or tens of...

gradient

gradient   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...generally taken to be a two-dimensional property, although three-dimensional gradients may become significant in the study of individual phenomena. Of particular importance are humidity , pressure , temperature , and thickness gradients. These are taken to be perpendicular to the corresponding isopleths . See also pressure gradient...

automatic picture transmission

automatic picture transmission   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...picture transmission ( APT ) The continuous transmission of images of the Earth by polar-orbiting meteorological satellites . The radiometer scan is perpendicular to the plane of the satellite's orbit, so that the image consists of a continuous swathe around the Earth. Data from two channels are normally transmitted simultaneously: visible and one infrared channel during daytime, and two infrared channels at night. See also high-resolution picture transmission ; Wefax...

ecliptic

ecliptic   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...The Sun's apparent path against the celestial sphere , which is, in fact, the projection of the Earth's orbit in space. Because the Earth's axis is not perpendicular to the plane of its orbit, the ecliptic cuts the celestial equator at two points, the vernal (spring) and autumnal equinoxes . It reaches its greatest elevation above and below the celestial equator at the summer and winter solstices ,...

ribbon lightning

ribbon lightning   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...occurs when a very strong wind is blowing at right angles to the observer's line of sight. The multiple strokes that form a single discharge are thus displaced horizontally from one another. A similar appearance may occur when the observer (or camera) is moving approximately perpendicular to the line of...

Pitot tube

Pitot tube   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...tube An instrument for measuring the relative velocity of a fluid. It functions by comparing the total pressure in an open tube facing into the airflow with the static pressure in a similar tube with an opening perpendicular to the flow. The dynamical pressure thus determined may be converted into wind speed. Often used on aircraft and, suitably mounted, as an anemometer or pressure -tube...

thermal wind

thermal wind   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

...wind The theoretical wind that blows parallel to the thickness lines in the layer between two specific isobaric surfaces . The name derives from the fact that low thickness values correspond to cold air, and high values to warm air. The thickness lines lie perpendicular to the temperature gradient. The geostrophic wind at the higher level is the sum of the vectors of the lower geostrophic wind and the thermal...

sastruga

sastruga   Quick reference

A Dictionary of Weather (2 ed.)

Reference type:
Subject Reference
Current Version:
2008

... ( zastruga , pl. sastrugi/zastrugi ) [Russian: ‘groove’] A wave-like irregularity in hard snow, normally perpendicular to the wind direction, sloping gently on the windward side and steeply to leeward. Sastrugi arise by the coalescence of snow dunes. The term is also applied to ridges parallel to the wind direction produced by mechanical abrasion by wind-borne ice particles, rather than simple deflation . The size of sastrugi depends on the state of the surface and the strength and duration of the wind. They may be up to 2 m high and often pose a...

lift

lift   Quick reference

A Dictionary of Energy Science

Reference type:
Subject Reference
Current Version:
2017
Subject:
Science and technology, Engineering and Technology, Environmental Science
Length:
152 words
Illustration(s):
1

...lift The component of force exerted on an aerofoil that is perpendicular to the direction of airflow ( see figure). There is also a drag force parallel to the direction of airflow. The differences in pressure arise as a result of the differences in air speed above and below the aerofoil ( see bernoulli’s principle ), and give rise to the lift. The force is given by , where ρ ‎ is the density of air, U is the air speed, A is the area of the aerofoil (given by the product of its chord (extent in the direction of flow) and span), and where C L ...

attenuator wave energy device

attenuator wave energy device   Quick reference

A Supplementary Dictionary of Renewable Energy and Sustainability

Reference type:
Subject Reference
Current Version:
2013

...wave energy device The classification of a wave energy device in terms of orientation, where the main axis is perpendicular to the wave front. Wave energy is drawn towards the device as the wave moves past it. These are long multi-segment floating structures, such as the Pelamis , which are anchored in place with a mooring line. The differing heights of waves along the length of the device cause flexing where the segments connect, and this movement drives hydraulic pumps or generators. Compare terminator wave energy devices and point absorber...

Wells turbine

Wells turbine   Quick reference

A Supplementary Dictionary of Renewable Energy and Sustainability

Reference type:
Subject Reference
Current Version:
2013

...an oscillating water column . Invented by Professor Alan Wells in the 1970s, the turbine is self-rectifying to accept air-flow in either axial direction. This is achieved by the use of symmetrical airfoil blades with a plane of symmetry in the plane of rotation and perpendicular to the air stream. The turbine causes a constant impedance to the airflow, which when matched to the wave climate at the chosen location, maximizes the energy-generating efficiency. It operates at high speeds between 1,500–3,000 rpm so that the electrical generator can be...

cover

cover  

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 ...

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