Relative humidity (or simply humidity) is the ratio of atmospheric vapor pressure to saturation vapor pressure.
The World Meteorological Organization prefers to define relative humidity as the ratio of specific humidity (or mixing ratio) to saturation mixing ratio, expressed in percent. It can be computed from wet-bulb temperature and related psychrometric data. Relative humidity (U, in percent) is expressed:
or
where e′ is the actual vapor pressure of the air and e w ′ the saturation vapor pressure at the same pressure and temperature. Mixing ratio (r) is defined as the ratio of mass of water vapor (m v ) to mass of dry air (m a ), thus r = m v /m a . Saturation occurs when moist air at pressure p and temperature T may exist in equilibrium with pure water or ice at the same temperature and pressure. In terms of mixing ratio (r) and saturation mixing ratio (r w ), it may be expressed:
Table 1provides relative humidity values derived, in this example, from temperature and...
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References
McIntosh, D. H. (ed.), 1963. Meteorological Glossary. London: Her Majesty's Stationery Office.
Meteorological Office, 1978. Elementary Meteorology. London: Her Majesty's Stationery Office.
Petterssen, S., 1956. Weather Analysis and Forecasting. vol. 2. New York: McGraw-Hill.
Wallace, J. M., and P. V. Hobbs, 1977. Atmospheric Sciences: An Introductory Survey. New York: Academic Press.
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© 1987 Van Nostrand Reinhold
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Fairbridge, R.W. (1987). Relative humidity . In: Climatology. Encyclopedia of Earth Science. Springer, Boston, MA. https://doi.org/10.1007/0-387-30749-4_148
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DOI: https://doi.org/10.1007/0-387-30749-4_148
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