Humidity

Steam control unit

Description

The amount of moisture vapor in the air. Humidity is a function of temperature and pressure (altitude). Absolute humidity is the number of pounds of water in dry air. Relative humidity is the absolute humidity divided by the maximum pounds of water that the air is capable of holding at that temperature. Thus, the air is totally saturated at 100% relative humidity. Some chemicals change color with humidity such as cobaltous chloride; it is pink when hydrated and blue when anhydrous.

Synonyms and Related Terms

absolute humidity; relative humidity; (Luft-)Feuchtigkeit (Deut.); humidité de l'air (Fr.); humidade (Port.)

Authority

• ASTM, Standard Terminology Relating to Conditioning, Annual Book of ASTM Standards, Section 6, Paints, Related Coatings and Aromatics, ASTM, E41, 23-24, Sep-92

• Boise Cascade Paper Group, The Paper Handbook, Boise Cascade, Portland OR, 1989

• Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982

• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

• Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000