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temperature unit
subject			fact

temperature unit	is a unit of temperature
	has triple point of water -has source: Jerrard, H.G., McNeill, D.B. 1992 Dictionary of Scientific Units, Chapman and Hall
	has absolute zero -has source: Jerrard, H.G., McNeill, D.B. 1992 Dictionary of Scientific Units, Chapman and Hall
	has definition A temperature unit is a measure of the average kinetic energy per degree of freedom of the constituent molecules.
	is a kind of unit
unit	has historical origin
	represents

Kinds of temperature unit :

• Celsius (12 facts) (°C, Centigrade) - A mercury-in-glass temperature scale. The zero of the scale represents the melting point of ice and the boiling point of water is taken to be 100 degrees.
• Curie temperature scale (3 facts) (magnetic temperature) - This is sometimes used for indicating temperature in the vicinity of absolute zero. It is based on Curie's law, which states that the susceptibility of a paramagnetic material is approximately proportional to its absolute temperature.
• Fahrenheit (6 facts) - A temperature scale based on three fixed temperature points - the temperature of an ice and salt mixture, the freezing point of water and normal human temperature - which were taken to be 0, 32 and 96 respectively. It is mere coincidence that the temperature interval between the freezing (32 °F) and boiling (212 °F) points of water is 180° when expressed in the Fahrenheit scale.
• helium temperature scale (3 facts) - The vapour pressure of helium 4 is used as an indication of temperature in the region 1 to 5.2 K.
• International temperature scale (4 facts) (ITS90) - A temperature scale defined between 0.65 K and the highest temperatures practicably measurable in terms of the Planck radiation law using monochromatic radiation. There are 17 fixed temperature points :
  • Below 5 K are defined in terms of the vapour pressures of helium 3 and helium 4
  • Between 5 K and the triple point of water are marked by the triple points of certain elements, e.g. neon (24.5561 K)
  • Above 0.01 °C are defined with reference to the freezing points of specified metallic elements
  • Upper limit is 1064.43 °C (1337.58 K), the freezing point of gold
  [JN92] -has source: J. A. Hall, 1967
• Kelvin (12 facts) (K, absolute) - The fraction 1/273.16 of the thermodynamic temperature of the triple point of water (the point at which the solid, liquid and gaseous phase of pure water are in equilibrium). Absolute zero corresponds to zero energy. Represents the same temperature interval as those on the Celsius scale., Unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water
• Rankine (7 facts) - A temperature scale with the same division as the Fahrenheit scale and the zero point at 0° absolute. 0 °R = - 470 °F., Unit which is 5/9 of the Kelvin. Rankine temperatures have the same temperature interval as those on the Fahrenheit scale.
• Reaumur (7 facts) - An arbitrary scale in which the freezing and boiling points of water are taken to be 0 and 80°R respectively. The scale is based on the thermal expansion of an alcohol and water mixture. If the 'length' is 1000 units at the ice point the length expands to 1080 units at the boiling point, hence the peculiar figure of 80 in this scale.