Despite their occurrence in the upper troposphere, ice-cloud formation remains one of the least understood processes in the atmosphere and one of the largest uncertainties in the prediction of climate change (IPCC 2014). However, coupling between in-situ aerosol measurements and computational models continue to improve our understanding of the formation and radiative effects of clouds in the atmosphere (Flossman and Wobrock, 2010). The principal objective of this research project is to complete the LaMP instrumental platform, through construction of an ice nucleation (IN) chamber that will be capable of sampling ambient and artificial aerosol particles into environments which permit the formation of ice crystals. The second objective of this project is to perform long-term in-situ measurements to try to understand the meteorological conditions and physical and chemical characteristics of aerosol particles required to act as ice nuclei. Once we understand the physical and chemical properties required to form an ice crystal we can begin to predict their formation in the atmosphere. The principal objectives of the laboratoire de Meteorologie physique are to study atmospheric particles and gases, and their chemical and physical interactions with cloud droplets. These research objectives are achieved through a combination of in-situ measurements and modelling studies. Our studies on clouds are focused on both aqueous-phase droplets and ice-crystals with in-situ measurements being made aboard an airborne platform and at the puy de Dome research station. Currently the LaMP is considered the leading French laboratory in ice-cloud experimental research as well as being recognised internationally for its ability to model liquid, mixed-phase, and ice clouds. This proposal is focused on understanding ice crystal formation in the atmosphere, and to characterise the chemical and physical properties of ice crystal residues. • The principal objective of this research project to complete the instrumental platform, through construction of an ice nucleation (IN) chamber that will, firstly, be capable of sampling ambient aerosol particles into environments which permit the formation of ice crystals. Secondly, it will be capable of introducing artificial aerosol particles into the chamber so that the dependence of the ice nucleating ability on aerosol composition, morphology, and concentration can be determined in different atmospheric environments (polluted vs. background). Thirdly this chamber will have a unique feature where it will be possible to chemically and physically characterise the ice crystals residues exiting the chamber. This feature is currently not performed with existing IN chambers. • The second objective of this project is to perform long-term in-situ measurements to try to understand the meteorological conditions and physical and chemical characteristics of aerosol particles required to act as ice nuclei. We plan to achieve this through coupling the IN chamber using a combination of online instruments (aerosol mass spectrometer, scanning particle mobility sizers) and offline instruments such as electron microscopy at the puy de Dome research site. This combination of instruments will provide us with detailed information on aerosol chemical and physical properties as well as obtaining more detailed information on particle mixing state and morphology through electron microscopy measurements. The combination of the IN chamber and the online/offline measurements will allow us to characterise the chemical and physical properties of ice crystal residues. Once we understand the physical and chemical properties required to form an ice crystal we can begin to predict their formation in the atmosphere. Additionally with this information we can begin to quantify the anthropogenic effects on ice-cloud formation.