| critical humidity [`krid·ǝ·kǝl yü`mid·ǝd·ē] CHEMICAL ENGINEERING The humidity of a system's atmosphere above which a crystal of a water-soluble salt will always become damp (absorb moisture from the atmosphere) and below which it will always stay dry (release moisture to the atmosphere). METALLURGY The atmospheric humidity above which the corrosion rate increases rapidly for a particular metal. |