Rankine scale
The Rankine scale is a thermodynamic (absolute) temperature scale. It is based around absolute zero. Rankine is similar to the Kelvin scale in that it starts at absolute zero and 0 °Ra is the same as 0 K but is different as a change of 1 °Ra is the same as a change of 1 °F (Fahrenheit) and not 1 °C (Celsius). Note that the abbreviation °R is ambiguous, as it can also refer to the Réaumur scale.