Definitions

Absolute zero: is the temperature at which all molecular motion ceases, or the energy of a molecule is zero.
British thermal unit (Btu): is defined as the amount of energy required to raise the temperature of 1 lb of pure water 1 F, at 68 F and 1 atm.
Calorie unit (SI): is defined as the amount of energy required to raise the temperature of 1g of pure water 1 C, at 4 C at 1 atm.
Celsius or Centigrade scale ( C): uses 0 and 100 (100 range) for the freezing and boiling points, respectively, of pure water at 1 atm.
Fahrenheit scale ( F): uses 32 and 212 (180 range) as the freezing and boiling points, respectively, of pure water at 1 atm.
Heat: is a form of energy, and is a measure of the vibration amplitude of its molecules, which is indicated by its temperature.
Joules (SI): are units of heat energy.
Kelvin scale (K): is referenced to absolute zero, and based on the Celsius scale.
Rankine scale ( R): is a temperature scale referenced to absolute zero, and based on the Fahrenheit scale.
Sublimation: is the direct transition from the gas state to the solid state without going into the liquid state, or the direct transition from the solid state to the gas state.

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Introduction to Instrumentation, Sensors, and Process Control