This session welcomes submissions on the formation, processing and interaction of ice particles in the atmosphere, based on laboratory investigations, aerosol chamber studies, distinctive field observations and theoretical modelling. A particular focus will be on the role of biological aerosols as ice nuclei and on the persistence of large ice supersaturation in the upper troposphere.

Only recently in ice-crystal residues of cirrus clouds a large fraction of biological material has been found. These bio-particles beside other organic IN might be responsible for high supersaturation ratios in respect to ice observed in the upper troposphere. Since cirrus ice clouds are important climate regulators and water vapour is the dominant greenhouse gas, it is crucial to understand these ice nucleation processes in detail. Laboratory models applied to these questions range from aerosol and cloud chambers to levitation traps and sophisticated reaction cells, often in close connection with field studies and modelling expertise.

There are many phenomena in atmospheric chemistry and physics in which ice is involved: including homogeneous and heterogeneous ice nucleation, secondary ice formation, processing of ice crystals in mixed phase cirrus clouds and PSCs, heterogeneous chemistry and uptake of trace gases on ice, morphology of ice crystals, inclusion of trace substances in the ice matrix, microphysical properties of mixed-phase and ice clouds, transport processes in mixed phase and ice clouds, radiative properties of mixed phase and ice clouds, influence of ice characteristics on precipitation processes, and the representation and role of the ice phase in weather and climate models.

This session intends to bring together research groups using different approaches and methodologies. The aim is to compare the different results and to develop joint strategies for future investigations and proposals. We particularly encourage submissions highlighting results from major national and international projects focused on ice-related processes.

The session will be open also to fundamental ice research from other areas as far as it includes common features with atmospheric ice particles.

Solicited Speakers: Ottmar Möhler (Karlsruhe Institute of Technology, D) and Claudia Marcolli (ETH Zürich, CH)