| 释义 |
isothermal, a. and n.|aɪsəʊˈθɜːməl|
[f. F. isotherme (see prec.) + -al1.]
A. adj.
1. Of, pertaining to, indicating, or corresponding to equal temperatures;
a. esp. in Phys. Geog. applied to a line (imaginary or on a map, etc.) connecting places on the earth's surface at which the temperature for a particular period, or (usually) the mean annual temperature, is the same; also to a map or chart exhibiting such lines.
1826Kirby & Sp. Entomol. IV. xlix. 484 Fixed by the will of the Creator, rather than..regulated by any isothermal lines. 1830Lyell Princ. Geol. I. 106 The lines of equal winter temperature do not coincide with the lines of equal annual heat, or the isothermal lines. 1880Haughton Phys. Geol. vi. 278 In Europe..51° N. Lat., which corresponds to the same isothermal line as 39° N. Lat. in America.
b. Applied to (imaginary) lines or surfaces of equal heat in a crystal or other body when heated.
1854J. Scoffern in Orr's Circ. Sc., Chem. 137 In crystals having two optic axes..if a centre of heat be assumed to exist within, and the crystal to be indefinitely extended in all directions, the isothermal surfaces will be ellipsoids with three unequal axes. 1871B. Stewart Heat §281. 1895 Story-Maskelyne Crystallogr. i. §11 As the form is invariably found to be either circular or elliptical, the continuous isothermal surface which would result from the maintenance of a given temperature at a point inside a crystal must be either a sphere, a spheroid, or an ellipsoid.
c. Applied to a line in a diagram that represents states or conditions of equal temperature.
1873J. W. Gibbs in Trans. Connecticut Acad. Arts & Sci. II. 311 In the same way we may conceive of lines..of equal temperature... These lines we may also call..isothermal. 1922Glazebrook Dict. Appl. Physics I. 930/1 When a perfect gas expands isothermally PV is constant, and hence its isothermal line on the pressure-volume diagram, for any assigned temperature, is a rectangular hyperbola. 1949F. Tyler Intermediate Heat vii. 146 The relative slopes of the isothermal and adiabatic curves passing through the point P1..may be obtained as follows.
2. Occurring at a constant temperature; pertaining to or involving a constancy of temperature with time.
1887Encycl. Brit. XXII. 481/1 During isothermal expansion a gas must take in an amount of heat just equal to the work it does. 1937M. W. Zemansky Heat & Thermodynamics xiii. 231 The isothermal compressibility of a gas may be calculated from an empiric equation expressing the dependence of V upon P at constant temperature. 1957Encycl. Brit. VIII. 123/2 Under ordinary conditions the adiabatic constants for a solid substance are practically the same as the corresponding isothermal constants. 1967A. H. Cottrell Introd. Metall. xx. 373 Decisive progress [in the heat-treatment of steel] came only after the development of the technique of isothermal transformation..in which specimens are quenched into a bath of molten lead or salt at some pre-determined temperature and the course of their transformation at this fixed temperature is then determined.
3. Of the same temperature throughout.
1909Rep. Brit. Assoc. Adv. Sci. 1908 591 Permit me to open the discussion on the Isothermal Layer, and the inversions of temperature which are found there. 1912H. N. Dickson Climate & Weather iii. 77 At heights greater than about nine miles the temperature..remains nearly constant at about -70°F at all levels... In this ‘isothermal layer’..there would seem to be..little movement. 1951J. A. Hynek Astrophysics xiv. 662 It is possible that at this stage..the star develops a small isothermal core at the center. 1964Oceanogr. & Marine Biol. II. 71 In winter the fiord water becomes isothermal and isohaline with average temperature and salinity of -1·76°C and 32·75{pmil}.
B. n.
a. An isothermal line or surface; an isotherm.
1852Dana Crust. ii. 1453 The difficulty of dividing this space by convenient isothermals. 1872Nicholson Palæont. 503 The present limit of trees is the isothermal which gives the mean temperature of 50° Fahr. in July, or about the parallel of 67° N. latitude. 1875Lyell Princ. Geol. II. ii. xxxiii. 231 The planes of the subterranean isothermals or surfaces of equal temperature being thus made to vary. 1875Academy 21 Aug. 201/1 Professor Mayer describes the method invented by him for obtaining registers of the isothermals on the sun's disc.
b. A line in a diagram that is isothermal (sense A. 1 c).
1873J. W. Gibbs in Trans. Connecticut Acad. Arts & Sci. II. 323 In that part of any diagram which represents a mixture of vapor and liquid, the isopiestics and isothermals will be identical, as the pressure is determined by the temperature alone. 1879Amer. Jrnl. Sci. XVIII. 463 In Diagram A, are drawn Isothermals, curves of equal temperature, in which the abscissæ are wave lengths, the ordinates intensities. 1937P. S. Epstein Textbk. Thermodynamics iii. 49 The slope of the adiabatic (dp/dv = - γp/v) is always steeper than the slope of the isothermal (dp/dv = - p/v) passing through the same point. 1968Wallace & Linning Basic Engin. Thermodynamics 458 At very low pressures all isothermals tend towards a value of the compressibility function equal to unity, i.e. towards perfect gas behaviour.
So also isothermobath |aɪsəʊˈθɜːməʊbæθ| [Gr. βάθος depth], a line connecting points of equal temperature at various depths in a vertical section of the sea; isoˈthermous a. = isothermal a.
1876Sir C. W. Thomson, Isothermobath. 1855Mayne Expos. Lex. s.v. Isothermus, Isothermous lines do not follow the parallels at the equator. |