isobarn.
/ˈʌɪsəʊbɑː/ Physical Geography and Meteorology.
1.
a. A line (drawn on a map or chart, or imaginary) connecting places on the earth's surface at which the barometric pressure is the same (at a given time, or on the average for a given period); an isobaric line. Also attributive.
ΘΚΠ
the world > the earth > weather and the atmosphere > weather > study or science of weather > diagrams, graphs, or lines > [noun] > barometric pressure
profile1860
isobar1864
electrogram1877
barogram1884
isallobar1911
the world > the earth > earth sciences > geography > map-making > map > [noun] > line on map > pressure
isobar1864
1864 in Webster's Amer. Dict. Eng. Lang.
1878 T. H. Huxley Physiography (ed. 2) 94 Another isobar [in the Times weather-chart] stretches across Scotland, and indicates a pressure of 29·9 inches.
1880 Times 16 Aug. 11/4 In the above chart the dotted lines are ‘isobars’ or lines of equal barometrical pressure.
1880 A. Geikie Elem. Lessons Physical Geogr. (new ed.) ii. 55 Charts showing, by means of lines of equal pressure called Isobars, the general distribution of atmospheric pressure.
1927 W. G. Kendrew Climates of Continents 8 The isobar map of the earth for January.
b. A line in a diagram that represents states or conditions of equal pressure.
ΘΚΠ
the world > matter > gas > air > [noun] > air-pressure > line in diagram indicating equal
isopiestic1873
isobar1892
isobaric1903
1892 P. Alexander Treat. Thermodynamics v. 39 An isobar is a constant pressure thermogram.
1924 A. E. Hill in H. S. Taylor Treat. Physical Chem. I. ix. 383 The isobar ab drawn at 1 atmosphere pressure intersects the curve BO at −78·3°.
1969 S. M. Blinder Adv. Physical Chem. viii. 144 In Fig. 8.2, the same data are represented as a series of isobars, plots of V versus t for fixed P.
2. Physics. Each of two or more nuclides which have the same mass number but different atomic numbers (and so are different elements). Originally † isobare n. (obsolete).
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the world > matter > chemistry > atomic chemistry > [noun] > atoms > specific types of atoms
functional group1892
species1895
hetero-atom1900
radio-atom1905
isobar1918
donor1927
impurity atom1939
nuclide1947
strong collider1968
1918 A. W. Stewart in London, Edinb. & Dublin Philos. Mag. 26 331 These elements [sc. mesothorium and radiothorium] differ completely from one another in chemical character; but they all possess the same atomic weight. For this reason the name isobares..is here suggested for them.
1919 F. Soddy in Trans. Chem. Soc. 115 23 We have to take into account in our analysis of matter, not only the heterobaric heterotopes before recognised, but also heterobaric and isobaric isotopes and isobaric heterotopes or isobares.
1922 F. W. Aston Isotopes 12 Isobares.
1928 M. Steel Physical Chem. & Biophysics ii. 37 Any product of radioactive change due to the loss of a beta particle..is an isobar of the parent element.
1946 Electronic Engin. 18 88/2 Neptunium and plutonium are isobares (same atomic mass but different atomic number).
1952 Sci. News 23 37 These nuclei are called isobares.
1954 K. Rankama Progr. Isotope Geol. xxv. 302 The isotope 40K is the active nuclide in the series of the three neighbouring isobars, 40A40K40Ca.
1955 R. D. Evans Atomic Nucleus iii. 99 The chemical properties of isobars are generally dissimilar, but their nuclear properties tend to present many parallel features.
1966 C. S. G. Phillips & R. J. P. Williams Inorg. Chem. II. xxxv. 621 We shall use the symbol Z for the number of protons in a nucleus (i.e. the atomic number) and N for the number of neutrons, so that A = Z + N, where A is the mass number or ‘rounded’ atomic weight. All nuclei of the same Z are called isotopes, of the same N isotones, and of the same A isobars.
This entry has not yet been fully updated (first published 1900; most recently modified version published online March 2021).
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n.1864