Dewcell

Dewcell (centre) with the protective guard used for storage and transportation on the left and the cover used while in operation on the right

Dewcells,[1][2] dewcels[3] or dew cell[1][4] are instruments used for determining the dew point. They consist of a small heating element surrounded by a solution of lithium chloride. As the LiCl absorbs moisture from the air, conduction across the heating element increases, current in it increases, and heat increases, evaporating moisture from the salt solution. At a certain temperature the amount of moisture absorbed by the salt solution equals the amount evaporated (equilibrium).

Inside the dewcell core a thermistor composite (or other temperature measurement device) changes electrical resistance with the temperature created by the heating. A front end processor provides a reference voltage, measures the output of the network, and calculates the dew point.

References

  1. 1 2 Public Works and Government Services Canada Translation Bureau
  2. ↑ WMO and Eumetcal
  3. ↑ MANOBS Chapter 6 - Humidity 6.5 Dewcel
  4. ↑ Some limitations and errors inherent in the use of the dew cell for measurement of atmospheric dew points
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