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|      Temperature Sensor      |                            Operating Principle                             |     Reference      |
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| BEAD THERMISTOR              | The electrical resistance of a spherical ceramic element changes with      | WMO (1983)         |
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| BIMETAL                      | Two metals of different expansivity (usually invar and steel or invar and  | WMO (1983)         |
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| BIMETAL COIL                 | A bimetal in the shape of a coil.                                          | WMO (1983)         |
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| BIMETAL STRIP                | A bimetal in the shape of a strip.                                         | WMO (1983)         |
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| BOURDON TUBE                 | Uncertain. (Bourdon tubes are generally associated with pressure           |                    |
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| CAPACITIVE TYPE              | Uncertain.  Probably, sensor capacitance varies with temperature.          |                    |
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| CERAMIC FLAKE                | Uncertain.                                                                 |                    |
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| ELECTROLYTIC TYPE            | Uncertain.                                                                 |                    |
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| ROD THERMISTOR               | The electrical resistance of a cylindrical ceramic element changes with    | WMO (1983)         |
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| THERMISTOR                   | The electrical resistance of a ceramic element changes with temperature.   | WMO (1983)         |
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| THERMOCAP - BEAD             | The capacitance of a dielectric ceramic bead changes with temperature.     | Vaisala Met        |
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| WIRE RESISTOR                | The resistance of a metal wire changes with temperature.                   | WMO (1983)         |
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