Fahrenheit
American Heritage Dictionary:
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Fahr·en·heit
(făr'ən-hīt') 
adj. (Abbr. F)
Of or relating to a temperature scale that registers the freezing point of water as 32° and the boiling point as 212° at one atmosphere of pressure.
adj. (Abbr. F)
Of or relating to a temperature scale that registers the freezing point of water as 32° and the boiling point as 212° at one atmosphere of pressure.
[After Gabriel Daniel FAHRENHEIT.]
Oxford Dictionary of Units & Measures:
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Fahrenheit
[Etymology: G. D. Fahrenheit; Poland, Netherlands 1686-1736] temperature. Symbols deg F, degree F, °F. A scale and a unit of temperature, its defining points being 32 at the freezing point of pure water and 212 at its boiling point, thus with 180 degrees between the two. Readings on the scale are expressed usually as °F, temperature intervals preferably as deg F or degree F, sometimes F°. The equivalent ‘absolute’ scale, with identically sized units but its zero at the thermodynamic null, is the Rankine scale.
See temperature for other scales and conversions between scales.
History
Created by its namesake in about 1712 (perhaps exactly contemporaneously with the creation of the Celsius or Centigrade scale), the Fahrenheit scale was used widely in the English-speaking world until recently. With the extensive adoption of the SI system, it is now only a relic except in the USA, where it remains the prevailing customary scale.
The original reference points appear to have been zero at the freezing point of heavy brine and 96° (nominally 100) at normal human body temperature. This unusual pattern derives from Newton's duodecimal mind recommending 12 subdivisions from ordinary freezing point to body temperature, then Roemer, with a compatible sexagesimal mind, adopting 60 subdivisions from the freezing of brine to boiling point. Fahrenheit's greater precision prompted a further subdivision on a binary basis, four-fold relative to Roemer and more so relative to Newton.
Fahrenheit, seeking the lowest possible practical temperature, doped his brine with ammonium chloride, so he had his zero clearly below Roemer's. With the four-fold increase over Roemer, the scale became 240 for boiling point, something like 100 for body temperature and 32 for the freezing of normal water. A scale set as described was then further modified to make the boiling point of water exactly 212°, making the freezing-to-boiling point 180 degrees for ordinary water, a number often seen as a coincidence but more likely to have been deliberate, being the number of degrees (of another type) in two right angles or the straight line, and completely in tune with the sexagesimal beginnings. This shift also meant that normal body temperature is somewhat higher than the original 96°, being subsequently regarded as 98.4 else 98.6°. The outcome was a scale that had, essentially by design, the points 0° and 100° corresponding closely to the lower and upper limits of human comfort, an approach which made the scale inherently preferable in many everyday contexts, and would have been as equally effective as the Celsius scale relative to science. However, Celsius was the more familiar to the creators of the metric system; ‘the rest is history’.
Dictionary of Cultural Literacy: Technology:
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Fahrenheit
Fahrenheit (FAIR-uhn-heyet)
A temperature scale, used primarily in the United States, in which the freezing point of water is 32 degrees and the boiling point 212 degrees. Temperatures in this scale are denoted by °F or, in scientific usage, F alone. (Compare Celsius.)
Barron's Food Lover's Companion:
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Fahrenheit
[FEHR-uhn-hite] A temperature scale in which 32° represents freezing and 212° represents the steam point. The scale was devised by Gabriel Daniel Fahrenheit, an 18th-century German physicist. To convert Fahrenheit temperatures to celsius subtract 32 from the Fahrenheit reading, multiply by 5 and divide by 9.
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Anders Celsius
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Anders Celsius
Fahrenheit temperature scale (fâr'ənhīt'), temperature scale in which the temperature difference between two reference temperatures, the melting and boiling points of water, is divided into 180 equal intervals called degrees. The freezing point is taken as 32°F and the boiling point as 212°F. The scale was established by the German-Dutch physicist Gabriel Daniel Fahrenheit in 1724. William John Macquorn Rankine used it as the basis of his absolute temperature scale, now called the Rankine temperature scale, in 1859. Although the Fahrenheit scale was formerly used widely in English-speaking countries, many of these countries began changing to the more convenient Celsius temperature scale in the late 1960s and early 1970s; a notable exception is the United States, where the Fahrenheit scale is still in common use together with other English units of measurement. Temperatures on the Fahrenheit scale can be converted to equivalent temperatures on the Celsius scale by first subtracting 32° from the Fahrenheit temperature, then multiplying the result by 5/9, according to the formula (F−32)5/9=C.
Cosmic Lexicon:
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Fahrenheit
A temperature scale with the freezing point of water assigned the value 32o F and the boiling point of water 212o F.
Dictionary of Cultural Literacy: Science:
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Fahrenheit
Wiley Dictionary of Flavors:
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Fahrenheit
The scale of temperature measurement wherein 32 degrees represents the freezing point of water and 212 degrees represents the boiling point of water. See Temperature, Absolute Zero.
Random House Word Menu:
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categories related to 'Fahrenheit'
- Forecasting and Meteorology - Fahrenheit: thermometric scale of 180 degrees with freezing point of water at 32 degrees and boiling point at 212 degrees, designated F
- Heat - Fahrenheit: temperature scale with 32 degrees equal to freezing point of water and 212 degrees equal to boiling point of water at standard atmospheric pressure
- Tools, Tests, Units, and Scales - Fahrenheit: F; temperature scale based on 32 degrees as freezing point and 212 degrees as boiling point of water at one atmosphere of pressure
Wikipedia on Answers.com:
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Fahrenheit
For other uses, see Fahrenheit (disambiguation).
Fahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit (1686–1736).[1] Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees. The Fahrenheit scale was replaced by the Celsius scale in most countries during the mid to late 20th century,[2] though Canada retains it as a supplementary scale that can be used alongside Celsius.[3][4][5][6] Fahrenheit remains the official scale of the United States, Cayman Islands and Belize.[7] The Rankine temperature scale was based upon the Fahrenheit temperature scale, with its zero representing absolute zero instead.
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Definition and conversions
| from Fahrenheit | to Fahrenheit | |
|---|---|---|
| Celsius | [°C] = ([°F] − 32) × 5⁄9 | [°F] = [°C] × 9⁄5 + 32 |
| Kelvin | [K] = ([°F] + 459.67) × 5⁄9 | [°F] = [K] × 9⁄5 − 459.67 |
| Rankine | [°R] = [°F] + 459.67 | [°F] = [°R] − 459.67 |
| For temperature intervals rather than specific temperatures, 1 °F = 1 °R = 5⁄9 °C = 5⁄9 K Comparisons among various temperature scales |
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On the Fahrenheit scale, the freezing point of water is 32 degrees Fahrenheit (°F) and the boiling point 212 °F (at standard atmospheric pressure). This puts the boiling and freezing points of water exactly 180 degrees apart.[8] Therefore, a degree on the Fahrenheit scale is 1⁄180 of the interval between the freezing point and the boiling point. On the Celsius scale, the freezing and boiling points of water are 100 degrees apart. A temperature interval of 1 °F is equal to an interval of 5⁄9 degrees Celsius. The Fahrenheit and Celsius scales intersect at −40° (−40 °F and −40 °C represent the same temperature).
Absolute zero is defined as −273.15 °C or −459.67 °F. The Rankine temperature scale was created to use degree intervals the same size as those of the Fahrenheit scale, such that a temperature difference of one degree Rankine (1 °R) is equal to a difference of 1 °F, except that absolute zero is 0 °R – the same way that the Kelvin temperature scale matches the Celsius scale, except that absolute zero is 0 K.[8] The Fahrenheit scale uses (in the same manner as the later Celsius scale) the symbol ° to denote a point on the temperature scale and the letter F to indicate the use of the Fahrenheit scale (e.g. "Gallium melts at 85.5763 °F"),[9] as well as to denote a difference between temperatures or an uncertainty in temperature (e.g. "The output of the heat exchanger experiences an increase of 72 °F" and "Our standard uncertainty is ±5 °F").
History
According to an article Fahrenheit wrote in 1724, he based his scale on three reference points of temperature.[8] In his initial scale (which is not the final Fahrenheit scale), the zero point is determined by placing the thermometer in brine: he used a mixture of ice, water, and ammonium chloride, a salt, at a 1:1:1 ratio. This is a frigorific mixture which stabilizes its temperature automatically: that stable temperature was defined as 0 °F (−17.78 °C). The second point, at 32 degrees, was a mixture of ice and water without the ammonium chloride at a 1:1 ratio. The third point, 96 degrees, was approximately the human body temperature, then called "blood-heat".[10]
According to a letter Fahrenheit wrote to his friend Herman Boerhaave,[11] his scale was built on the work of Ole Rømer, whom he had met earlier. In Rømer's scale, brine freezes at zero, water freezes and melts at 7.5 degrees, body temperature is 22.5, and water boils at 60 degrees. Fahrenheit multiplied each value by four in order to eliminate fractions and increase the granularity of the scale. He then re-calibrated his scale using the melting point of ice and normal human body temperature (which were at 30 and 90 degrees); he adjusted the scale so that the melting point of ice would be 32 degrees and body temperature 96 degrees, so that 64 intervals would separate the two, allowing him to mark degree lines on his instruments by simply bisecting the interval six times (since 64 is 2 to the sixth power).[10][12]
Fahrenheit observed that water boils at about 212 degrees using this scale. Later, other scientists decided to redefine the degree slightly to make the freezing point exactly 32 °F, and the boiling point exactly 212 °F or 180 degrees higher.[citation needed] It is for this reason that normal human body temperature is approximately 98° (oral temperature) on the revised scale (whereas it was 90° on Fahrenheit's multiplication of Rømer, and 96° on his original scale).[13]
Usage
The Fahrenheit scale was the primary temperature standard for climatic, industrial and medical purposes in English-speaking countries until the 1960s. In the late 1960s and 1970s, the Celsius scale (known until 1948 as centigrade) replaced Fahrenheit in many countries, typically during their metrication process.[14]
Fahrenheit is used in the United States, Belize, and the United States territories of Puerto Rico, Guam and the U.S. Virgin Islands[7] for everyday applications. For example, U.S. weather forecasts, food cooking, and freezing temperatures are typically given in degrees Fahrenheit. Scientists, such as meteorologists, use Celsius or Kelvin in all countries.[15] In some nations, both measures are quoted.[16]
Various reasons are given[who?] for the resistance to the Celsius system in the U.S., including the larger size of each degree Celsius (resulting in the need for decimals where integer Fahrenheit degrees were adequate for much non-technical work).[citation needed] Another reason is the lower zero point in the Fahrenheit system which reduces the number of negative signs when measurements such as weather data were averaged.[17]
In some countries, Fahrenheit may be used in daily life alongside Celsius. For example, Canada has passed legislation favouring the International System of Units, while also maintaining legal definitions for traditional Canadian imperial units.[18] Canadian weather reports are conveyed using degrees Celsius with occasional reference to Fahrenheit especially for trans border broadcasts. Virtually all Canadian ovens make legal use of the Fahrenheit scale.[19] Thermometers, both digital and analogue, sold in Canada usually employ both the Celsius and Fahrenheit scales.[20][21][22]
Fahrenheit is also utilized in the United Kingdom alongside Celsius. Weather reports displayed in newspapers and online quote temperatures in both Celsius and Fahrenheit (or have an option to enable this), especially during record-breaking weather.[23] However, TV weather reports are primarily conveyed using degrees Celsius. Cooking instructions on most packaged food also list dual temperature scales along with digital/analogue thermometers.
Unicode representation of symbol
The Fahrenheit symbol has its own Unicode character: "℉"(U+2109). This is a compatibility character encoded for roundtrip compatibility with legacy CJK encodings (which included it to conform to layout in square ideographic character cells) and vertical layout. Use of compatibility characters is discouraged by the Unicode Consortium. The ordinary degree sign (U+00B0) followed by the Latin letter F ("°F") is thus the preferred way of recording the symbol for degree Fahrenheit.
See also
References
- ^ Robert T. Balmer (2010). Modern Engineering Thermodynamics. Academic Press. p. 9. ISBN 978-0-12-374996-3. http://books.google.com/?id=VC-RuN6moREC&pg=PA9&dq=fahrenheit+temperature+scale+inventor+book#v=onepage&q=fahrenheit%20temperature%20scale%20inventor%20book&f=false. Retrieved 2011-07-17.
- ^ "Metric usage and metrication in other countries". http://lamar.colostate.edu/~hillger/internat.htm. Retrieved 2009-12-11.
- ^ Weights and Measures Act, accessed February 2012, Act current to 2012-01-18. Canadian units (5) The Canadian units of measurement are as set out and defined in Schedule II, and the symbols and abbreviations therefore are as added pursuant to subparagraph 6(1)(b)(ii).
- ^ Weights and Measures Act
- ^ Transportation Safety Board of Canada, accessed February 2012, Rail Report - 1996 - R96C0135. Section 1.0 (1.7 Particulars of the Track) The CWR was laid at a rail temperature of 85 degrees Fahrenheit (F). The desired laying temperature for this region is 85 °F. The rail temperature at Mile 119.8 shortly after the derailment location was noted to be 105 °F.
- ^ Environment Canada, accessed February 2012. Environment Canada (Canada's government sanctioned weather bureau), unlike Britain's Met Office and Australia's Bureau of Meteorology etc, offers an imperial option alongside the metric. This is in full compliance with Canadian law and would not otherwise be available if the Fahrenheit scale (and indeed all other imperial measurements) did not have legal recognition in Canada.
- ^ a b Belize National Meterotrological Service (2011-07-17). "Current Conditions". http://www.hydromet.gov.bz/. Retrieved 2011-07-17.
- ^ a b c Walt Boyes (2009). Instrumentation Reference Book. Butterworth-Heinemann. pp. 273–274. ISBN 978-0-7506-8308-1. http://books.google.com/?id=ZvscLzOlkNgC&pg=PA273&lpg=PA273&dq=rankine+temperature+scale+book#v=onepage&q=rankine%20temperature%20scale%20book&f=false. Retrieved 2011-07-17.
- ^ Preston–Thomas, H. (1990). "The International Temperature Scale of 1990 (ITS-90)". Metrologia 27: 6. Bibcode 1990Metro..27....3P. doi:10.1088/0026-1394/27/1/002. http://www.bipm.org/utils/common/pdf/its-90/ITS-90_metrologia.pdf. Retrieved 2011-07-17.
- ^ a b Frautschi, Steven C.; Richard P. Olenick, Tom M. Apostol, David L. Goodstein (2008-01-14). The mechanical universe: mechanics and heat. Cambridge University Press. p. 502. ISBN 978-0-521-71590-4.
- ^ Ernst Cohen and W.A.T. Cohen-De Meester. Chemisch Weekblad, volume 33 (1936), pages 374–393, cited and translated in http://www.sizes.com:80/units/temperature_Fahrenheit.htm
- ^ Cecil Adams. "On the Fahrenheit scale, do 0 and 100 have any special significance?". The Straight Dope. http://www.straightdope.com/classics/a4_188.html.
- ^ Elert, Glenn; Forsberg, C; Wahren, LK (2002). "Temperature of a Healthy Human (Body Temperature)". Scandinavian Journal of Caring Sciences 16 (2): 122–8. doi:10.1046/j.1471-6712.2002.00069.x. PMID 12000664. http://hypertextbook.com/facts/LenaWong.shtml. Retrieved 2008.
- ^ [1] Information about New Zealand's money and metric measures
- ^ "782 - Aerodrome reports and forecasts: A user's handbook to the codes". World Meteorological Organization. http://www.wmo.int/e-catalog/detail_en.php?PUB_ID=70&SORT=N&q=Aerodrome%20Reports%20and%20Forecasts. Retrieved 2009-09-23.
- ^ Cayman Islands government weather service, which gives Fahrenheit first and Celsius second accordingly.
- ^ Halsey, Frederick A., Dale, Sanuel S. (1919). The metric fallacy (2 ed.). The American Institute of Weights and Measures. pp. 165–166, 176–177. http://books.google.com/?id=xRMPAAAAYAAJ&pg=PA165&dq=centigrade+too+large#PPA166,M1. Retrieved 2009-05-19.
- ^ "Canadian Units of Measurement; Department of Justice, Weights and Measures Act (R.S.C., 1985, c. W-6)". Current to 2011-05-17. http://laws-lois.justice.gc.ca/eng/acts/W-6/page-19.html#h-17. Retrieved June 5, 2011.
- ^ Pearlstein, Steven (2000-06-04). "Did Canada go metric? Yes - and no". The Seattle Times. http://community.seattletimes.nwsource.com/archive/?date=20000604&slug=4024917. Retrieved June 5, 2011.
- ^ "Example of analogue thermometer frequently used in Canada". http://www.canadiantire.ca/AST/browse/2/OutdoorLiving/GardenDecor/ClocksThermometers/PRD~0429116P/12-in.%252BThermometer%25252C%252BWhite.jsp?locale=en. Retrieved June 6, 2011.
- ^ "Example of digital thermometer frequently used in Canada". http://www.canadiantire.ca/AST/browse/3/HouseHome/HomeDecor/Thermometers/PRD~0429929P/Deluxe%252BWeather%252BStation.jsp?locale=en. Retrieved June 6, 2011.
- ^ Department of Justice (2009-02-26). "Canadian Weights and Measures Act". Federal Government of Canada. http://laws.justice.gc.ca/eng/W-6/page-2.html. Retrieved 2011-07-17.
- ^ "A week-long heatwave and 100F summer ahead; Express Newspaper,". May 7, 2008. http://www.express.co.uk/posts/view/43698. Retrieved Dec 27, 2011.
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Translations:
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Fahrenheit
Dansk (Danish)
adj. - Fahrenheit
n. - Fahrenheit
Nederlands (Dutch)
Fahrenheit (kookpunt 212, vriespunt 32)
Français (French)
adj. - Fahrenheit
n. - échelle Fahrenheit
Deutsch (German)
adj. - (Meteor.) Fahrenheit
n. - (Meteor.) in Großbritannien und USA gebräuchliches Temperaturmesssystem
Ελληνική (Greek)
adj. - (βαθμοί) Φαρενάιτ
Italiano (Italian)
gradi Fahrenheit
Português (Portuguese)
adj. - Fahrenheit
Русский (Russian)
по Фаренгейту
Español (Spanish)
adj. - perteneciente a la escala de temperatura Fahrenheit
n. - escala de temperatura Fahrenheit
Svenska (Swedish)
adj. - Fahrenheit-, enligt Fahrenheits skala
中文（简体）(Chinese (Simplified))
华氏温度计的, 华氏的, 华氏温度计
中文（繁體）(Chinese (Traditional))
adj. - 華氏溫度計的, 華氏的
n. - 華氏溫度計
한국어 (Korean)
adj. - 호사시의
n. - 호사시
日本語 (Japanese)
n. - カ氏温度計, ファーレンハイト, 華氏温度計
adj. - 華氏の
idioms:
- degrees fahrenheit 華氏温度
العربيه (Arabic)
(صفه) فهرنهايتي
עברית (Hebrew)
adj. - פרנהייט
n. - סולם מעלות-חום שהמים קופאים בו ב-23 מעלות ורותחים ב-212
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Copyrights:
American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Oxford Dictionary of Units & Measures
A Dictionary of Weights, Measures, and Units. Copyright © Donald Fenna 2002, 2004. All rights reserved.
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Dictionary of Cultural Literacy: Technology
The Dictionary of Cultural Literacy, Second Edition, Revised and updated Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 1993 by Houghton Mifflin Company . All rights reserved.
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Barron's Food Lover's Companion
Food Lover's Companion. Copyright © 2001 by Barron's Educational Series, Inc. All rights reserved.
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Columbia Encyclopedia
The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2012, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/.
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Dictionary of Cultural Literacy: Science
The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. All rights reserved.
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Wiley Dictionary of Flavors
Copyright © 2008 by Wiley-Blackwell. Wiley and the Wiley logo are registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries. Used here by license. Read more
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This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Fahrenheit.
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Mentioned in
Fahrenheit Scale
(science)
Fahrenheit, Gabriel Daniel
(German-born physicist)
F
(abbreviation)
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