Definition of isobar in English:

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Pronunciation: /ˈʌɪsə(ʊ)bɑː/


Image of isobar
1 Meteorology A line on a map connecting points having the same atmospheric pressure at a given time or on average over a given period.
Example sentences
  • Secret Meteorological Office charts show the alarming swirl of isobars converging in black lines over the Channel.
  • The tight spacing of the isobars indicates strong northerly winds, averaging some 50 km/h over much of Victoria.
  • When isobars on a weather chart are close together, it will be a blustery day…
1.1 Physics A curve or formula representing a physical system at constant pressure.
Example sentences
  • The heating isobar for the transformed monolayers remained virtually superimposable on the curve for films that had experienced no rapid compression.
  • No discontinuous change occurs in either the compression isotherm or the heating isobar.
  • For the heated film, the substantial reversion of the transformed film to the original behavior occurred without any discontinuous change in area or in the slope of the heating isobar.
2 Chemistry Each of two or more isotopes of different elements, with the same atomic weight.



Pronunciation: /ʌɪsə(ʊ)ˈbarɪk/
Example sentences
  • A phase transition produced by isothermally increasing surface pressure can often be reversed during isobaric heating.
  • This diagram is the same as the one above except that the major pressure and wind zones have been replaced by a typical isobaric weather map.
  • For all simulations, isothermal and isobaric conditions were assumed.


Mid 19th century: from Greek isobaros 'of equal weight', from isos 'equal' + baros 'weight'.

For editors and proofreaders

Line breaks: iso¦bar

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