latent heatn.
/ˌleɪt(ə)nt ˈhiːt/, U.S. /ˌleɪtnt ˈhit/ Physics.
Originally: the heat required to convert a solid into liquid or vapour, or a liquid into vapour. In later use more widely: the energy released or absorbed when an object or substance undergoes a physical change in which the temperature remains constant. Contrasted with sensible heat.Now typically measured in kilojoules per kilogram.
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the world > matter > physics > electromagnetic radiation > heat > [noun] > latent heat
latent heatc1757
latent caloric1798
c1757 J. Black Lect. (1803) I. 157 Considered as the cause of warmth, we do not perceive its presence; it is concealed or latent, and I gave it the name of latent heat.
1765 T. Reid Let. 20 Dec. in Wks. (1872) I. 42/2 I have attended Dr. Black's lectures hitherto. His doctrine of latent heat is the only thing I have yet heard that is altogether new.
1830 C. Lyell Princ. Geol. I. 466 A portion of the steam is at first condensed into water, and the temperature of the water is raised by the latent heat evolved.
1871 B. Stewart Heat (ed. 2) §91 The great latent heat of water serves to retard the melting of snow.
1922 T. M. Lowry Inorg. Chem. xxiv. 311 The latent heat of sublimation of iodine is about 15,000 calories per gram-molecule.
2001 P. Barham Sci. Cooking iv. 38 If we allow steam to cool down and condense (as for example when cooking in a steamer) it has to give up this latent heat to change from a gas to a liquid.
Phrases
latent heat of evaporation n. the energy required to convert (unit mass of) a liquid to a vapour at constant temperature.
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1846 Chemist 7 449/1 The latent heat of evaporation may also be considered as the difference of the total heats of the liquid and the vapour, at the temperature when the conversion into vapour takes place.
1933 A. W. Barton Text Bk. Heat ii. 58 State Trouton's law connecting the latent heat of evaporation with the absolute temperature of the boiling-point.
2012 I. C. Kemp in E. Tsotsas & A. S. Mujumdar Mod. Drying Technol. IV. i. 7 Dryer efficiency..is expressed as latent heat of evaporation divided by actual heat supplied to the air.
latent heat of fusion n. the energy required to convert (unit mass of) a solid to a liquid at constant temperature.
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1846 Chemist 7 448/2 It is evident that the latent heat of fusion is the difference between the total heats of the solid and the liquid, at the melting point.
1961 N. C. Breddy Introd. Refrigeration ii. 22 The standard unit of refrigeration is..equal to the latent heat of fusion of ice at 32°F. which is 144 B.Th.U./lb.
2003 M. Karel & D. B. Lund Physical Princ. Food Preserv. (ed. 2) viii. 314 The huge latent heat of fusion overwhelms the heat capacity of initially cold unfrozen portion and the temperature rises rapidly.
This entry has been updated (OED Third Edition, March 2015; most recently modified version published online March 2022).
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n.c1757