Clouds - their Formation and Importance for Present and Future Climate

Ulrike Lohmann (ETH Zurich)

Nov 10. 2023, 09:45 — 10:30

Clouds are not only fascinating to observe for their myriad of shapes, but are also scientifically challenging because their formation requires both knowledge about the large-scale meteorological environment as well as knowledge about the details of cloud droplet and ice crystal formation on the micro-scale.

Aerosol particles can scatter and absorb solar radiation and with that cause a cooling, that partly offsets the greenhouse gas warming. Aerosol particles also influence the microphysics of clouds by acting as cloud condensation nuclei (CCN) and ice nucleating particles (INPs). An increase in aerosol particles will lead to more and smaller cloud droplets for a given cloud water content, which leads to higher cloud albedo. The magnitude and geographical distribution of the cooling caused by aerosol particles themselves and by aerosol-cloud interactions are much more uncertain than the greenhouse gas warming because aerosol particles have localized sources and sinks and only have an atmospheric residence time of days to weeks. Aerosol effects on mixed-phase clouds (clouds containing cloud droplets and ice crystals at the same time) are more complex than on warm clouds because aerosol particles can act both as CCN and as INPs and more microphysical pathways exist.

Different suggestions exist, how clouds could be deliberately modified in order to alleviate some of the global warming.

In my talk I will explain how aerosol particles influence cloud formation and how they might be used in future to limit global warming to some extent.

Further Information
ESI Boltzmann Lecture Hall
Associated Event:
ESI@30 (Symposium)
Adrian Constantin (U of Vienna)
Christoph Dellago (U of Vienna)
Michael Eichmair (U of Vienna)
Stefan Fredenhagen (U of Vienna)
Ilaria Perugia (U of Vienna)
Bernadett Weinzierl (U of Vienna)