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A hot spring on the ocean floor, where heated fluids exit from cracks in the Earth's crust. Most hydrothermal vents occur along the central axes of mid-oceanic ridges, which are underwater mountain ranges that wind through all of the deep oceans.…

A navigation system that produces hyperbolic lines or surfaces of position by measuring the difference in times of reception (or phase difference) between radio signals from two or more synchronized transmitters. Such systems require the use of a…

The application of meteorological information to industrial, business, or commercial problems. Generally, industrial meteorology is a branch of applied meteorology, which is the broad field where weather data, analyses, and forecasts are put to…

Low-frequency sound waves that cannot be sensed by the human ear. Infrasound was first detected on barometers around the world following the eruption of the volcano Krakatoa in 1883. We now know subaudible sounds are generated by a wide variety of…

The incident radiant energy emitted by the Sun, which reaches a unit horizontal area of the Earth's surface. The term is a contraction of incoming solar radiation. About 99.9% of the Sun's energy is in the spectral range of 0.15–4.0 micrometers.…

A relatively complex response pattern that is usually present in one or both sexes of a given animal species. Instinctive behavior (see illustration) comprises any species-typical pattern of responses that are not clearly acquired through training.…

A developmental disorder characterized by significantly subaverage general intellectual functioning, with concurrent, significant deficits in adaptive behavior. Intellectual disability, formerly termed mental retardation, is a condition in which the…

Surfaces along which the entropy and potential temperature of air are constant. Potential temperature, in meteorological usage, is defined by the relationship given below,in which T is the air temperature, P is atmospheric pressure expressed in…

A curve along which pressure is constant. Leading examples of its uses are in weather forecasting and meteorology. The most common weather maps are charts of weather conditions at the Earth's surface and mean sea level, and they contain isobars as…

A line along which the speed of the wind is constant. Isotachs are customarily represented on surfaces of constant elevation or atmospheric pressure, or in vertical cross sections. The closeness of spacing of the isotachs is indicative of the…

A map showing the distribution of air temperature (or sometimes sea surface or soil temperature) over a portion of the Earth's surface, or at some level in the atmosphere. On it, isotherms are lines connecting places of equal temperature. The…

The complex, disseminated organic matter present in sedimentary rocks that remains undissolved by sequential treatment with common organic solvents (such as a benzene-methanol mixture, toluene, and methylene chloride) followed by treatment with…

The optical analog of radar. The term lidar is an acronym for light detection and ranging. Lidar systems employ intense pulses of light, typically generated by lasers, and large telescopes and sensitive optical detectors to receive the reflected…

An instrumental device that, in theory, could detect an involuntary physiological response that all persons exhibit when lying, but never when telling the truth. Lie detector tests rely on polygraphic recordings of palmar sweating, respiration, and…

An abrupt, high-current electric discharge that occurs in the atmospheres of the Earth and other planets and that has a path length ranging from hundreds of meters to tens of kilometers. Lightning occurs in thunderstorms because vertical air motions…

The science of language. Linguistics, that is, the scientific study of language, is concerned with the general and universal properties of language. Interest in language seems to have arisen in the earliest history of the human species. Every…

A navigation system from which hyperbolic lines of position are determined by measuring the difference in times of arrival of pulses from widely spaced, synchronized transmitting stations. Since radio waves travel at the speed of light, a line of…

The perceptual intensity of sound. Loudness depends importantly on the physical intensity of sound, increasing when physical intensity increases and decreasing when physical intensity decreases. In addition, loudness depends on other physical…

The common name for a number of perciform fishes in the family Scombridae, characterized by a long slender body, pointed head, and large mouth. The family Scombridae comprises mackerels and tunas. Mackerels have a fusiform and moderately compressed…

A compass depending for its directive force upon the attraction of the Earth's magnetism on a magnet free to turn in any horizontal direction. A compass is an instrument used for determining horizontal direction. Principle of operation The magnetic…

A cubic mineral and member of the spinel structure type, space group Fd3m, with composition [Fe3+]IV[Fe2+Fe3+]VIO4. It possesses the inverse spinel structure, in which half the ferric iron is tetrahedrally coordinated and the remaining half as well…

An instrument that measures the magnitude and/or direction of a magnetic field. A magnetometer can be either a scalar instrument that measures the magnitude of the total field or a vector instrument that measures one or more vector components of the…

A term applied commercially to any limestone or dolomite taking polish. Marble is extensively used for building and ornamental purposes.Limestone Stone and stone productsIn petrography the term marble is applied to metamorphic rocks composed of…

The collection and observation of living organisms in the sea, including the quantitative determination of their abundance in time and space. The biological survey of the ocean largely depends on specially equipped vessels. Sampling in intertidal…

The management of marine species and ecosystems to prevent their decline and extinction. As in terrestrial conservation, the goal of marine conservation is to protect biodiversity and ecosystem function through the preservation of species,…

An integrative science that studies the basic structural and functional relationships within and among living populations and their physical–chemical environments in marine ecosystems. Although an outgrowth of natural history and the life sciences,…

The harvest of animals and plants from the ocean to provide food for people and animals. Marine fisheries are places or industries engaged in the harvesting of aquatic life in seawaters. Important products in marine capture fisheries include fish…

A scientific discipline applying the principles and methods of general microbiology to research in marine biology and biogeochemistry. Marine microbiology investigates microorganisms living in saltwater environments. Dealing, by definition, with…

The process of directing a watercraft to a destination in a safe and expeditious manner. From a known present position, a course is determined that avoids dangers, and on this course estimates are made of time schedules. The task is to make periodic…

Interference with the audibility of a sound caused by the presence of another sound. More specifically, the number of decibels (dB) by which the intensity level of a sound (signal) must be raised above its threshold of audibility, to be heard in the…

The branch of geography that examines human and physical activities on the Earth's surface using models and statistical analysis. The primary areas in which mathematical methods are used include the analysis of spatial patterns, the processes that…

The mental ability to store and access information that has been acquired through experience. Memory (Fig. 1) is a critical component of practically all aspects of human thinking, including perception, learning, language, and problem solving.…

Clusters of emotional, cognitive, and/or behavioral symptoms in an individual reflecting an underlying psychobiological disturbance of sufficient severity to cause clinically significant distress or impairment in social or occupational functioning.…

An all-weather aircraft landing-guidance system that operates at microwave frequencies and provides deviations from the landing runway centerline using a time-referenced scanning beam (TRSB) technique. The MLS was standardized in 1988 and approved…

A naturally occurring solid phase with a restricted chemical composition and a definite atomic arrangement. This is really an idealized definition insofar as some minerals (especially those that form at low temperature) have poorly defined atomic…

A distorted scene of distant objects resulting from the passage of light through a nonuniform medium. In a uniform atmosphere light would travel in straight lines and distant scenes would appear without distortion. Since the density of the air…

The smallest of the four major deserts in the North American Desert region in the continental United States and is located in the southwestern quadrant of the Basin and Range physiographic province in southeastern California and portions of Arizona,…

A group name for all clay minerals with an expanding structure, except vermiculite, and also a specific mineral name for the high alumina end member of the group. VermiculiteMontmorillonite clays have wide commercial use. The high colloidal,…

Any of a number of procedures for the fitting of a selected geometric model to a body of multivariate data. In the original form advanced by Warren S. Torgerson, multidimensional scaling dealt with judgments about stimuli, with its major aim being…

An integrative field of research that analyzes brain activity while experimental subjects make decisions. Neuroeconomics is a consilient discipline (that is, a discipline that combines the principles of other disciplines to produce a comprehensive…

The scientific study of the effects of music on the brain. Neuromusicology is a scientific discipline concerned with the function of the brain in music processing. Although neuromusicology is an area of study that utilizes present-day neurological…

The formation of nuclides present in the universe by various nuclear reactions. Theories of the origin of the elements involve synthesis with charged and neutral elementary particles (neutrons, protons, neutrinos, photons) and other nuclear building…

An isolated fertile area, usually limited in extent and surrounded by desert. The term was initially applied to small areas in Africa and Asia typically supporting trees and cultivated crops with a water supply from springs and from seepage of water…

The general circulation of the ocean. The term is usually understood to include large-scale, nearly steady features, such as the Gulf Stream (Fig. 1), as well as current systems that change seasonally but are persistent from one year to the next,…

Propagating oscillations in the ocean that carry energy and momentum from one region to another. Most ocean waves (Fig. 1) are caused directly or indirectly by wind blowing across the sea surface. Many waves can propagate through the ocean thousands…

The science of the sea, including physical oceanography, marine chemistry, marine geology, and marine biology. The need to know more about the impact of marine pollution and possible effects of the exploitation of marine resources, together with the…

Waters of varying mineral content which are found associated with petroleum and natural gas or have been encountered in the search for oil and gas. They are also called oil-field brines, or brines. They include a variety of underground waters,…

One of the chemical senses, specifically the sense of smell. Olfaction comprises the action or capacity of smelling, and is a form of chemoreception (the ability of organisms to detect changes in the chemical composition of their exterior or…

A name given to a group of magnesium-iron silicate minerals crystallizing in the orthorhombic system. Crystals are usually of simple habit, a combination of the dipyramid with prisms and pinacoids. The luster is vitreous and the color olive green,…

The study of the abundance and composition of naturally occurring organic substances, their origins and fate, and the processes that affect their distributions on Earth and in extraterrestrial materials.Organic geochemistry was born from a curiosity…