1) Moisture 
science of humidity
• (n.) That branch of physics which relates to the determination of the humidity of bodies, particularly of the atmosphere, with the theory and use of the instruments constructed for this purpose.
The measurement of air humidity
Hy·grom'e·try noun [ Confer French hygrométrie .] (Physics) That branch of physics which relates to the determination of the humidity of bodies, particularly of the atmosphere, with the theory and use of the instruments constructed for this purpose. 
Rate of humidity in the air : for optimum conservation of a wine the level of hygrometry in the cellar should be about 70%.
Type: Term Pronunciation: hī-grom′ĕ-trē Synonyms: psychrometry
hygrometry 1. The scientific study and calculation of the relative humidity of the atmosphere. 2. That branch of physics which relates to the determination of the humidity of bodies, particularly of the humidity of air and gases in the atmosphere, with the theory and use of the instruments constructed for this purpose.
The subject of humidity measurement. 
the branch of physics that deals with the measurement of the humidity of air and gases.