The radiative role of ice clouds in the atmosphere is known to be important, but uncertainties remain concerning the magnitude and net effects. However, through measurements of the microphysical properties of cirrus clouds, we can better characterize them, which can ultimately allow for their radiative properties to be more accurately ascertained. It has recently been proposed that there are two types of cirrus clouds – in situ and liquid origin. In this study, we present observational evidence to show that two distinct types of cirrus do exist.

- "A. E. Luebke1,b, A. Afchine1, A. Costa1, J. Meyera, C. Rolf1, N. Spelten1, L. M. Avallone2,b, D. Baumgardner3, and M. Krämer1"