Rømerskala

The Rømerscale is an old temperature scale and is considered to be the forerunner of the Fahrenheit and Celsius scales . It was developed in 1701 by the Danish astronomer Ole Christensen Rømer (1644-1710). Temperatures on this scale are given in degrees Rømer (abbr .: ° Rø).

The zero point of the scale is defined by the melting point of brine . As a second reference point on the scale, Rømer used the boiling point of water and set this to 60 ° Rø. He obtained the values between these two points by linear graduation with interpolation . According to this scale, ice has a melting point of 7.5 ° Rø.

Daniel Gabriel Fahrenheit heard about the work of Rømer and visited him in 1708 . He adopted the idea of two reference points (boiling point and melting point of certain substances) and set himself the goal of improving this scale. In 1714 he developed the Fahrenheit scale from this . Also Celsius adopted the idea for its Celsius scale .

Temperature scales

Overview of the classic temperature scales
unit	Unit symbol	lower anchor point F ₁	upper anchor point F ₂	Unit value	inventor	Year of creation	Distribution area
Kelvin	K	Absolute zero point , T ₀ = 0 K	Now without a fixed point, originally later T _Tri ( H ₂ O ) = 273.16 K ${\ displaystyle 1 \, \ mathrm {K} \; {\ stackrel {\ mathrm {def}} {=}} \; 1 \, ^ {\ circ} \ mathrm {C}}$	${\ displaystyle 1 \, \ mathrm {K} = 1 {,} 380 \, 649 \ cdot 10 ^ {- 23} {\ frac {\ mathrm {J}} {k _ {\ mathrm {B}}}}}$ earlier ${\ displaystyle {\ frac {F_ {2} -F_ {1}} {273 {,} 16}}}$	William Thomson Baron Kelvin	1848	worldwide ( SI unit )
centigrade	° C	Now 0 ° C = 273.15 K, previously T _Schm (H ₂ O) = 0 ° C	Now coupling to Kelvin, previously T _boiling (H ₂ O) = 100 ° C	${\ displaystyle 1 \, ^ {\ circ} \ mathrm {C} \; {\ stackrel {\ mathrm {def}} {=}} \; 1 \, \ mathrm {K}}$ earlier ${\ displaystyle {\ frac {F_ {2} -F_ {1}} {100}}}$	Different Celsius	1742	worldwide ( derived SI unit )
degrees Fahrenheit	° F	Now 32 ° F = 273.15 K, originally T _cold.= 0 ° F, later T _Schm (H ₂ O) = 32 ° F	Now coupling to Kelvin, originally T _human = 96 ° F, later T _boiling (H ₂ O) = 212 ° F	${\ displaystyle 1 {,} 80 \, ^ {\ circ} \ mathrm {F} \; {\ stackrel {\ mathrm {def}} {=}} \; 1 \, \ mathrm {K}}$ originally later ${\ displaystyle {\ frac {F_ {2} -F_ {1}} {96}}}$ ${\ displaystyle {\ frac {F_ {2} -F_ {1}} {180}}}$	Daniel Fahrenheit	1714	United States
Rankine degree	° Ra, ° R	T ₀ = 0 ° Ra	Now coupling to Kelvin	${\ displaystyle 1 \, ^ {\ circ} \ mathrm {Ra} \; {\ stackrel {\ mathrm {def}} {=}} \; 1 \, ^ {\ circ} \ mathrm {F}}$	William Rankine	1859	United States
Degree Delisle	° De, ° D	T _Schm (H ₂ O) = 150 ° De	T _boiling (H ₂ O) = 0 ° De	${\ displaystyle {\ frac {F_ {1} -F_ {2}} {150}}}$	Joseph-Nicolas Delisle	1732	Russia (19th century)
Degree Réaumur	° Ré, ° Re, ° R	T _Schm (H ₂ O) = 0 ° Ré	T _boiling (H ₂ O) = 80 ° Ré	${\ displaystyle {\ frac {F_ {2} -F_ {1}} {80}}}$	René-Antoine Ferchault de Réaumur	1730	Western Europe until the end of the 19th century
Degrees Newtons	° N	T _Schm (H ₂ O) = 0 ° N	T _boiling (H ₂ O) = 33 ° N	${\ displaystyle {\ frac {F_ {2} -F_ {1}} {33}}}$	Isaac Newton	≈ 1700	none
Degree Rømer	° Rø	T _Schm ( Lake ) = 0 ° Rø	T _boiling (H ₂ O) = 60 ° Rø	${\ displaystyle {\ frac {F_ {2} -F_ {1}} {60}}}$	Ole Romer	1701	none
Notes on the table: ↑ T _Tri (H ₂ O) has been at 273.16 K since the redefinition in May 2019 with a relative uncertainty of 3.7 · 10 ⁻⁷ according to Le Système international d'unités . 9e édition, 2019 (the so-called "SI brochure", French and English), pp. 21 and 133. ↑ The temperature of a cold mixture of ice, water and salmiak or sea salt (−17.8 ° C) and the supposed "body temperature of a healthy person" (35.6 ° C) were originally used ↑ The melting temperature of a brine (−14.3 ° C) was used.

Temperature conversion

Conversion between the temperature units
→ from →		Kelvin (K)	Degrees Celsius (° C)	Degrees Fahrenheit (° F)	Rankine degree (° Ra)
↓ to ↓		Kelvin (K)	Degrees Celsius (° C)	Degrees Fahrenheit (° F)	Rankine degree (° Ra)
T _Kelvin	=	T _K	T _C + 273.15	(T _F + 459.67) ⁵ ⁄ ₉	T _Ra · ⁵ / ₉
T _Celsius	=	T _K - 273.15	T _C	(T _F - 32) ⁵ ⁄ ₉	T _Ra · ⁵ / ₉ - 273.15
T _Fahrenheit	=	T _K * 1.8 - 459.67	T _C * 1.8 + 32	T _F	T _Ra - 459.67
T _Rankine	=	T _K * 1.8	T _C * 1.8 + 491.67	T _F + 459.67	T _Ra
T _Réaumur	=	(T _K - 273.15) x 0.8	T _C x 0.8	(T _F - 32) ⁴ ⁄ ₉	T _Ra · ⁴ / ₉ - 218.52
T _Rømer	=	(T _K - 273.15) ²¹ ⁄ ₄₀ + 7.5	T _C · ²¹ / ₄₀ + 7.5	(T _F - 32) ⁷ ⁄ ₂₄ + 7.5	(T _Ra - 491.67) ⁷ ⁄ ₂₄ + 7.5
T _Delisle	=	(373.15 - T _K ) x 1.5	(100 - T _C ) x 1.5	(212 - T _F ) ⁵ ⁄ ₆	(671.67 - T _Ra ) ⁵ ⁄ ₆
T _Newtons	=	(T _K - 273.15) x 0.33	T _C x 0.33	(T _F - 32) ¹¹ ⁄ ₆₀	(T _Ra - 491.67) ¹¹ ⁄ ₆₀

→ from →		Degree Réaumur (° Ré)	Degree Rømer (° Rø)	Degree Delisle (° De)	Degree Newton (° N)
↓ to ↓		Degree Réaumur (° Ré)	Degree Rømer (° Rø)	Degree Delisle (° De)	Degree Newton (° N)
T _Kelvin	=	T _Ré 1.25 + 273.15	(T _Rø - 7.5) ⁴⁰ ⁄ ₂₁ + 273.15	373.15 - T _De · ² / ₃	T _N · ¹⁰⁰ / ₃₃ + 273.15
T _Celsius	=	T _Ré 1.25	(T _Rø - 7.5) ⁴⁰ ⁄ ₂₁	100 - T _De · ² / ₃	T _N · ¹⁰⁰ / ₃₃
T _Fahrenheit	=	T _Ré · 2.25 + 32	(T _Rø - 7.5) ²⁴ ⁄ ₇ + 32	212 - T _De 1.2	T _N · ⁶⁰ / ₁₁ + 32
T _Rankine	=	T _Ré · 2.25 + 491.67	(T _Rø - 7.5) ²⁴ ⁄ ₇ + 491.67	671.67 - T _De * 1.2	T _N · ⁶⁰ ⁄ ₁₁ + 491.67
T _Réaumur	=	T _Ré	(T _Rø - 7.5) ³² ⁄ ₂₁	80 - T _De · ⁸ / ₁₅	T _N · ⁸⁰ / ₃₃
T _Rømer	=	T _Re · ²¹ / ₃₂ + 7.5	T _Rø	60 - T _De 0.35	T _N · ³⁵ / ₂₂ + 7.5
T _Delisle	=	(80 - T _Ré ) · 1.875	(60 - T _Rø ) ²⁰ ⁄ ₇	T _De	(33 - T _N ) ⁵⁰ ⁄ ₁₁
T _Newtons	=	T _Re · ³³ / ₈₀	(T _Rø - 7.5) ²² ⁄ ₃₅	33 - T _De · 0.22	T _N

[zwei-1] T _Tri (H ₂ O) has been at 273.16 K since the redefinition in May 2019 with a relative uncertainty of 3.7 · 10 ⁻⁷ according to Le Système international d'unités . 9e édition, 2019 (the so-called "SI brochure", French and English), pp. 21 and 133.

[drei-2] The temperature of a cold mixture of ice, water and salmiak or sea salt (−17.8 ° C) and the supposed "body temperature of a healthy person" (35.6 ° C) were originally used

[vier-3] The melting temperature of a brine (−14.3 ° C) was used.