The length of the arc of a meridian between the equator and a given parallel on a Mercator chart, expressed in units of 1 minute of longitude at the equator.
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ARC
A flash, caused by an electric current ionizing a gas or vapor.
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GREENWICH HOUR ANGLE
Angular distance west of the Greenwich celestial meridian; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of the Greenwich celestial meridian and the hour circle of a point on the celestial sphere, measured westward from the Greenwich celestial meridian throug
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GROWLER
A piece of ice smaller than a BERGY BIT or FLOEBERG, often transparent but appearing green or almost black in color. It extends less than 1 meter above the sea surface and its length is less than 20 feet (6 meters). A growler is large enough to be a hazard to shipping but small enough that it may escape visual or radar detection.
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LAMINAR FLOW
A flow situation in which fluid moves in parallel lamina or layers.
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SHEAR RATE
The difference between the velocities along the parallel faces of a fluid element divided by the distance between the faces.
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BYPASS FILTRATION
A system of filtration in which only a portion of the total flow of a circulating fluid system passes through a filter at any instant or in which a filter having its own circulating pump operates in parallel to the main flow.
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ATOMIC ABSORPTION SPECTROSCOPY
Measures the radiation absorbed by chemically unbound atoms by analyzing the transmitted energy relative to the incident energy at each frequency. The procedure consists of diluting the fluid sample with methyl isobutyl ketone (MIBK) and directly aspirating the solution. The actual process of atomization involves reducing the solution to a fine spray, dissolving it, and finally vaporizing it with a flame. The vaporization of the metal particles depends upon their time in the flame, the flame temperature, and the composition of the flame gas. The spectrum occurs because atoms in the vapor state can absorb radiation at certain well-defined characteristic wave lengths. The wave length bands absorbed are very narrow and differ for each element. In addition, the absorption of radiant energy by electronic transitions from ground to excited state is essentially and absolute measure of the number of atoms in the flame and is, therefore, the concentration of the element in a sample.
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ANGSTROM UNITS
A unit of wave length, equal in length to one ten billionth.
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GRID PARALLEL
A line parallel to a grid equator, connecting all points of equal grid latitude
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ARC FURNACE
An electric furnace, in which heat is produced by an arc between two electrodes.
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