A cryometer is a
thermometer
A thermometer is a device that measures temperature (the hotness or coldness of an object) or temperature gradient (the rates of change of temperature in space). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb ...
used to measure very low temperatures of objects. Ethanol-filled thermometers are used in preference to mercury for meteorological measurements and can measure temperatures in the range of . Their main physical limitation is the freezing and boiling point of the liquid used.
There are many types of devices used as cryometers to measure temperatures below the freezing point of common liquids:
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thermocouples: these can be used down to measure about 1 K temperature.
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vapour pressure thermometers: these can be used to measure temperatures down to about 0.5K
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resistance thermometers
Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to measure temperature. Many RTD elements consist of a length of fine wire wrapped around a heat-resistant ceramic or glass core but other construction ...
: these can be used to measure temperatures at 0.01 K.
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melting curve thermometers: these can be used to measure temperatures between about 0.001K and 0.5K
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resistance noise thermometers: these can be used to down to about 0.001K
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magnetic thermometers: which are used at 0.001 K temperatures.
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nuclear-resonance thermometers: these are required to measure very low temperatures such as 0.0000001 K.
References
*Oxford dictionary of science, 1999, 4th edition, .
Thermometers
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