The effect of cirrus of varying optical depth on the extraterrestrial net radiative flux

✍ Scribed by C. M. R. Platt

• Book ID: 104575360
• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 396 KB
• Volume: 107
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49710745313

✦ Synopsis

Abstract

A simple model has been used to investigate the effects on the net radiation at the top of the atmosphere of a change in cirrus optical depth at various latitudes. the model employs relationships between the cloud solar albedo and the cloud infrared emittance which are based on theoretical considerations and also supported by recent observations. the model is used to predict the change in net radiant flux at the top of the atmosphere with a unit change in cloud amount and with a change in cloud emittance. Generally, tropical and mid‐latitude cirrus clouds cause a warming effect until the optical depths become large. For optical depths greater than about 12 for tropical cirrus, and about 5 for mid‐latitude cirrus, an increase in cloud will cause a cooling tendency.

The importance of specifying the correct albedo‐emittance relationships is emphasized by a comparison of the solar reflection properties of cirrus using two different theoretical models; one model envisages cirrus as composed of ice (or water) spheres and the other as composed of long ice cylinders. Recent observations tend to support the cylinder model.