Aircraft measurements of solar and infrared radiation and the microphysics of cirrus cloud

✍ Scribed by G. W. Paltridge; C. M. R. Platt

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 846 KB
• Volume: 107
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49710745208

✦ Synopsis

Abstract

Profiles of the upward and downward solar and infrared flux densities and of the downward beam radiance at 11 μm are reported for six cirrus cloud decks over Socorro, New Mexico. the data are used to derive empirical relations between vertical ice‐water path (obtained from simultaneously measured particlesize distributions) and solar absorptance, solar albedo, broad‐band infrared flux emittance and the 11μm beam emittance. As a guide, for ice‐water paths of about 75 gm^−2^ where the infrared emittances are approaching unity, the solar albedo is about 0.4, the solar absorptance is of the order of 0.15 and the geometrical thicknesses are between 1.5 and 2.5 km. Within an individual cloud there is little variation of particle size distribution with height, but the geometrically thicker clouds favour large particles. No icecrystal shape information is available, but the observed relation between albedo and emittance suggests that theoretical treatment of cirrus ice particles as ‘cylinders’ is better than treatment as ‘equivalent spheres’.