Clouds play an important role for the Earth's energy budget. They reflect sunlight (a cooling effect - cloudy days are cooler) and exert, on the other hand, a greenhouse effect (a warming effect - cloudy nights are warmer).

The question, how cloud distributions and cloud properties alter in a changing climate and so further warm (positive feedback) or rather cool (negative feedback) the Earth's surface constitutes one of the main uncertainties for model projections of future climate change.

The main reason for this is the broad range of scales on which cloud processes act (down to the "microphysics", in which precipitation formation processes are analysed at the scale of individual cloud droplets), which can't be resolved by climate models usually having resolutions of hundred kilometres. Such processes are therefore "parameterised".

A scheme developed at the Max Planck Institute for Meteorology describes the statistical variability of water vapour and cloud water inside a grid-box ("subgrid-scale distribution").

The Junior Research Group applies this approach to systematically improve the representation of clouds in the climate model. The simulated cloud processes are evaluated and improved exploiting observational data (in particular, new satellite data). Observations are further be used to analyse cloud-climate feedbacks, and cloud feedback processes in the complex coupled Earth system compared to the atmosphere alone are investigated.

Please find an overview of our activities in the interim report for the German research foundation.