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On the cloud absorption anomaly
Author(s) -
Stephens Graeme L.,
Tsay SiChee
Publication year - 1990
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 - 10.1002/qj.49711649308
Subject(s) - absorption (acoustics) , cloud computing , reflection (computer programming) , atmospheric sciences , meteorology , environmental science , radiation , water vapor , liquid water content , computational physics , remote sensing , physics , optics , geology , computer science , programming language , operating system
This paper provides an overview of the subject of absorption of solar radiation by water clouds in the earth's atmosphere. the paper summarizes the available evidence which points to disagreements between theoretical and observed values of both cloud absorption and reflection. the importance of these discrepancies, particularly to remote sensing of clouds as well as to studies of cloud physics and earth radiation budgets, is emphasized. Existing cloud absorption and reflection measurements are reviewed and the persistent differences that exist between calculated and measured near‐infrared cloud albedos are highlighted. Various explanations for these reflection and absorption discrepancies are discussed and a simple outline of the theory of cloud absorption is provided. This outline is used to examine the large‐droplet hypothesis as well as the effects of absorbing aerosol and enhanced water vapour continuum absorption. A further hypothesis regarding the effects of cloud inhomogeneities is also examined. While the theory of cloud absorption is not completely understood, especially with regard to inhomogeneous clouds, the underlying conclusion of this paper points to the need for better measurements of solar radiation in clouds, water vapour absorption and microphysics properties of clouds.