The beginning of every cloud’s existence is simply humid air. When it condenses and forms water droplets, it sometimes grows into a mountain range of clouds that weighs tons and glides over us. Or it turns into rain.
Clouds determine the water cycle of the Earth, as well as its weather and climate. Not every cloud brings rain or snow. Ice nuclei play a decisive role in the formation of precipitation. These enable the formation of ice in clouds. Only ice particles - in contrast to liquid cloud droplets - can grow so large that they are heavy enough to fall out of the cloud as rain, sleet, hail or snow.
The research group INUIT (Ice Nuclei Research Unit) investigates how ice forms in the atmosphere by means of laboratory experiments, field measurements and modelling. It is clear that ice nuclei are necessary to trigger the first ice formation in so-called mixed phase clouds. However, there are still many outstanding scientific questions regarding the concentration and variability of the ice nuclei-forming particles and their physical-chemical properties. The results will help to better simulate cloud processes and to quantify the contribution of various ice nuclei types and freezing modes.
INUIT is a cooperative project between Goethe University Frankfurt and Johannes Gutenberg University Mainz, the Max Planck Institute for Chemistry, University of Bielefeld, the Leibniz Institute for Tropospheric Research (TROPOS), the Karlsruhe Institute of Technology (KIT), the Technical University Darmstadt and the Weizmann Institute in Israel. Around 50 German researchers and one Israeli researcher are involved in the nine subprojects, including meteorologists, physicists, biologists, chemists and geoscientists. The project is funded by the German Research Foundation (DFG) and will run until December 2018.