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A description of cloud production by non‐uniformly distributed processes
Author(s) -
Bushell Andrew C.,
Wilson Damian R.,
Gregory David
Publication year - 2003
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1256/qj.01.110
Subject(s) - cloud computing , fraction (chemistry) , volume fraction , cloud fraction , forcing (mathematics) , volume (thermodynamics) , distribution (mathematics) , mechanics , environmental science , physics , thermodynamics , meteorology , cloud cover , statistical physics , atmospheric sciences , mathematics , mathematical analysis , chemistry , computer science , organic chemistry , operating system
Prognostic cloud‐fraction and condensate equations, for the case in which a source injects condensate‐laden, saturated air into a volume, are derived by considering the response of a general distribution of thermodynamic variables within the volume. These prognostic equations are compared with those derived by assuming that condensate is added uniformly to both clear and cloudy parts of the region. For non‐uniform forcing, the local condensate mixing ratio associated with the condensate source is important in controlling the rate of change of cloud fraction and in‐cloud condensate. For the case of a convective condensate source, the cloud‐fraction equation is contrasted with previously derived alternatives. Lastly, the validity of a prognostic equation for cloud fraction is discussed in the light of a different approach in which the moments of a distribution of thermodynamic variables are specified from prognostic equations and used to calculate cloud fraction and condensate diagnostically. © Crown copyright, 2003. Royal Meteorological Society