ITN CLOUD-MOTION

Duration: 2017-2021

Contact: Imad El Haddad, imad.el-haddad@psi.ch

CLOUD (cosmics leaving outdoor droplets) is an experiment that uses a 3-m stainless-steel chamber at CERN to study the possible link between galactic cosmic rays and cloud formation. Current experiments are designed to better understand aerosol nucleation processes in different environments (i.e. the formation of new particles from condensing vapors) to provide reliable aerosol physics for climate models as well as ice nucleation and ice nucleating particles (pre-existing aerosols which aid heterogeneous ice nucleation) which can significantly affect cloud radiative and microphysical properties. These data will help to quantify the direct and indirect radiative effects of aerosols on climate, which are recognized as the largest source of uncertainty in climate forcing contributed by mankind.

The CLOUD-MOTION project is funded by the EU (Marie Curie Initial Training Network MSCA-ITN project no. 764991) and involves an interdisciplinary team of scientists from 16 institutes in 7 countries, comprised of atmospheric physicists, solar physicists, and cosmic-ray and particle physicists.

Our contribution to the project are the development and employment of instruments for the measurement of

• particle size distributions (nano-SMPS, SMPS, CPC 2.5)
• gas concentrations (such as NO_x, ammonia, and CO)
• state of the art particle and gas phase mass spectrometers (EESI-TOF, AMS)

In a recent paper published in Nature, the CLOUD collaboration presents measurements of extremely rapid growth rates caused by condensation of nitric acid and ammonia as well as new particle formation from these vapours at low temperatures It is expected that these rapid growth rates increase survival probability of particles in polluted areas, and nucleation may  provide an important source of new particles in the cold upper free troposphere.