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| Titel |
Factors controlling upper tropospheric relative humidity |
| VerfasserIn |
B. Kärcher, W. Haag |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 22, no. 3 ; Nr. 22, no. 3 (2004-03-19), S.705-715 |
| Datensatznummer |
250014795
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| Publikation (Nr.) |
 copernicus.org/angeo-22-705-2004.pdf |
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| Zusammenfassung |
Factors controlling the distribution of relative humidity in the absence of clouds are examined, with
special emphasis on relative humidity over ice (RHI) under upper tropospheric and lower stratospheric
conditions. Variations of temperature are the key determinant for the distribution of RHI, followed
by variations of the water vapor mixing ratio. Multiple humidity modes, generated by mixing of different
air masses, may contribute to the overall distribution of RHI, in particular below ice saturation. The
fraction of air that is supersaturated with respect to ice is mainly determined by the distribution of
temperature. The nucleation of ice in cirrus clouds determines the highest relative humdity that can be
measured outside of cirrus clouds. While vertical air motion and ice microphysics determine the slope of
the distributions of RHI, as shown in a separate study companion (Haag et al., 2003), clouds are not required to
explain the main features of the distributions of RHI below the ice nucleation threshold.
Key words. Atmospheric composition and structure (pressure,
density and temperature; troposphere – composition
and chemistry; general or miscellaneous) |
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