Absolute humidity
mass of water vapour present in unit volume of moist air of a given temperature and pressure.
Absorption
retention of water vapour by penetration into the bulk of a material.
Adiabatic
addition of moisture with a corresponding reduction in temperature. This process involves direct evaporation of water in the air without external energy (e.g. water spray). The heat for vaporisation is taken from the air thus cooling it.
Atomising
conversion of bulk liquid into a spray or mist (i.e. collection of drops), often by passing the liquid under pressure through a nozzle.
Condensation
change of water from its gaseous form (water vapour) into liquid water. Condensation generally occurs in the atmosphere when warm air rises, cools and looses its capacity to hold water vapour.
Dew point
temperature to which the air must be cooled at constant pressure in order for it become saturated, i.e., the relative humidity becomes 100%.
Hygroscopic
materials, whose cells exchange moisture with the surrounding environment. Hygroscopic materials have a greater dimensional change due to humidity rather than temperature.
Humidity
presence of water vapour in air or other gas.
Isothermal
addition of moisture without an increase in temperature. This process uses steam & requires external energy to change the state of the water into a gas by boiling.
Moisture
liquid water or water vapour in any form, can be also used to mean water that is absorbed or bound into any material.
Relative humidity (RH)
ratio of actual vapour present in the air to the maximum quantity of moisture that the air can hold at the same temperature.
Steam
vaporised water.