Infrared spectral absorption of nearly invisible cirrus clouds

The SUbsonic aircraft Contrail and Cloud Effects Special Study (SUCCESS) was conducted 8 April–10 May 1996 to better understand the radiative properties of high level ice crystal clouds produced by anthropogenic (i.e., jet aircraft) and natural (i.e., weather) causes. In this paper multispectral radiance data observed during SUCCESS from the high flying NASA ER‐2 aircraft are presented to demonstrate that nearly ‘invisible’ high level layers of very small ice particles can cause very significant absorption (50% or more) of the upwelling infrared radiation to space.