dry-bulb thermometer

noun

variants or dry bulb thermometer

plural dry-bulb thermometers or dry bulb thermometers

: a thermometer that uses a bulb filled with liquid (such as mercury or alcohol) to register a reading of the temperature of the atmosphere based on the known expansion rate of the liquid : a thermometer that measures dry-bulb temperature

The dry-bulb thermometer, as the name would imply is an ordinary mercury thermometer the bulb of which is maintained in a dry state.

—T. Morris Fraser

A wet piece of cloth covers the bulb of one, the wet-bulb thermometer, which is cooled by evaporation of water in the cloth. The other thermometer, a dry-bulb thermometer, measures the air temperature. The difference between the two thermometers' readings is used in a mathematical formula to determine the dew point and relative humidity.

—The New York Times

Word History

First Known Use

1830, in the meaning defined above