Standard Article

Relative Humidity


  1. Climent Ramis,
  2. Romualdo Romero,
  3. Sergio Alonso

Published Online: 15 JUL 2005

DOI: 10.1002/047147844X.me321

Water Encyclopedia

Water Encyclopedia

How to Cite

Ramis, C., Romero, R. and Alonso, S. 2005. Relative Humidity. Water Encyclopedia. 4:270–274.

Author Information

  1. University of the Balearic, Palma de Mallorca, Spain

Publication History

  1. Published Online: 15 JUL 2005


The air is a mixture of gases. The pressure exerted by air is the sum of the partial pressures exerted by each of its components (Dalton's law). The partial pressure exerted by water vapor, denoted as vapor pressure (e), is then a measure of the water vapor content in the atmosphere. A state can be represented by a point in a diagram whose coordinates are (temperature, vapor pressure) = (T, e).

For each temperature, a maximum vapor pressure exists that is known as the saturation vapor pressure (es). That saturation value cannot be surpassed, and if water vapor in excess occurs, condensation or sublimation results.


  • vapor pressure;
  • partial pressure;
  • condensation;
  • sublimation