isobar

isobar (ī`səbär') or isobaric line (ī'səbăr`ĭk), line drawn on a weather map through points of equal atmospheric pressure. Isobars are used to define cyclones (low-pressure regions) and anticyclones (high-pressure regions). Weather maps are designed to depict the horizontal pressure distribution across an area of land, but atmospheric pressure also varies vertically, i.e., with altitude. To eliminate any consideration of the vertical variations of pressure, the barometer readings at all stations are reduced to their corresponding sea-level pressures before the isobars are drawn.

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isobar

1. Meteorology a line on a map connecting places of equal atmospheric pressure, usually reduced to sea level for purposes of comparison, at a given time or period

2. Physics any of two or more atoms that have the same mass number but different atomic numbers

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isobar [′ī·sə‚bär]

(meteorology)

A line drawn through all points of equal atmospheric pressure along a given reference surface, such as a constant-height surface (notably mean sea level on surface charts), an isentropic surface, or the vertical plan of a synoptic cross section.

(nuclear physics)

One of two or more nuclides having the same number of nucleons in their nuclei but differing in their atomic numbers and chemical properties.

(physics)

A line connecting points of equal pressure along a given surface in a physical system.

A line connecting points of equal pressure on a graph plotting thermodynamic variables.

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Isobar (nuclear physics)

One of two or more atoms which have a common mass number A but which differ in atomic number Z. Thus, although isobars possess approximately equal masses, they differ in chemical properties; they are atoms of different elements. Isobars whose atomic numbers differ by unity cannot both be stable; one will inevitably decay into the other. See Electron capture, Radioactivity