## Temperature conversion

Temperature is a measure of the average kinetic energy of a collection of particles or objects. The molecules of a gas, a liquid or a solid body are in constant motion. The motion increases with rising temperature. At the possibly lowest temperature (absolute zero point) this movement comes  to the standstill.

The temperature is measured according to the International System SI in degrees Celsius (° C) or Kelvin (K).

The Fahrenheit unit for temperature was defined 1714 by the scientist Gabriel Daniel Fahrenheit.

He determined the lowest temperature he could produce for the zero point. With a freezing mixture of ice, water and ammonia he reached -17.78 ° C (= 0 ° Fahrenheit).
Finally, the freezing point and the boiling point of water were defined as fixed points and divided into 180 scale divisions.
The normal body temperature of 37.7° Celsius is thus at approx. 100 ° Fahrenheit (99.86 ° F).

To convert the temperature TF (°F) to TC (°C):

TC = 5/9 ( TF/°F - 32) * °C

The Swedish scientist Anders Celsius defined in 1742 the freezing point of water as 100 ° C and the steam point as 0°C. Only later both values ​​were exchanged resulting in the now common temperature scale in degrees Celsius.

The Kelvin scale goes back to the English physicist William Thomson, who was ennobled to Lord Kelvin. In contrast to the Kelvin or Fahrenheit scale the zero point is not defined by the water characteristic or a salt mixture, but above the absolute zero point. The movement of particles doesn`t take place there. A temperature difference of 1K corresponds to a temperature difference of 1 ° C.

TC = ( TK/K - 273,15) * °C

The temperature measurement in Fahrenheit (F) is mainly common in the US, but also in England. The temperature measurement in Kelvin is used in science.

The Rankine scale has zero point at absolute zero point and the scale intervals of the Fahrenheit scale.The absolute temperature in Fahrenheit base is denoted by degrees Rankine (° Rank).

An outdated temperature scale is the Réaumur scale (° R).
It corresponds to the following fixed points:
0 °C <=> 0 °R
100 °C <=> 80 °R

Celsius /°C Fahrenheit /°F Kelvin /K Rankine /°Rank Réaumure /°R
-273,15 -459,67 0 0 0
-17,7777 0 259,45 459,67 -14.2222
0 32 273,15 491,67 0
37,7 99,86 310,85 559,53 30,16
100 212 373,15 671,67 80

### Formula for the calculation in Kelvin

Celsius (TC) to Kelvin (TK) TK = TC + 273,15
Fahrenheit (TF) to Kelvin (TK) TK = 5/9 * (TF + 459,67)
Rankine (TRank) to Kelvin (TK) TK = 5/9 * TRank
Réaumure (TR) to Kelvin (TK) TK = 5/4 * TR + 273,15