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See also: Isobar


A weather map showing isobars
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From Ancient Greek ἴσος ‎(ísos, equal) + βάρος ‎(báros, weight)


isobar ‎(plural isobars)

  1. (meteorology) A line drawn on a map or chart connecting places of equal or constant pressure.
  2. (nuclear physics) Either of two nuclides of different elements having the same mass number.
  3. (thermodynamics) A set of points or conditions at constant pressure.

Usage notes[edit]

  • (meteorology):
    In meteorology, the term isobar most often refers to a line drawn through connected points of equal atmospheric pressure on a given reference surface — such as a constant height surface (notably mean-sea-level on surface charts), the vertical plane of a synoptic cross section, or a layer of the air unaffected by surface heating or cooling. The pattern of isobars has always been a main feature of surface chart analysis. (See Wikipedia-logo.png Surface weather analysis on Wikipedia.Wikipedia:Surface weather analysis) Until recently it was standard procedure to draw isobars at 3-millibar intervals. However, the advent of constant pressure charts for upper-air analysis has brought about the use of 4-millibar intervals to simplify the conversion from surface isobars to 1,000-millibar contour lines.


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See also[edit]



isobar ‎(not comparable)

  1. isobaric


External links[edit]