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|       Humidity Sensor       |                 Operating Principle                 |     Reference      |
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| CARBON HYGRISTOR            | Finely divided carbon particles are suspended in a  | WMO (1983)         |
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| GOLDBEATERS SKIN            | A membrane from the intestine of an ox (used        | WMO (1983)         |
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| HUMAN HAIR                  | The length of human hair increases with increasing
 | WMO (1983)         |
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| HUMICAP - BEAD              | A thin-film sensor whose capacitance varies with    | Vaisala Met        |
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| LiCl HYGRISTOR              | The resistance of an strip coated with an           | WMO (1983)         |
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| RE-DESIGNED RH DUCT         | Humidity sensor is housed in a newly                | None               |
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| ROLLED HUMAN HAIR           | The length of human hair increases with             | WMO (1983)         |
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