Aarhus University (The Contracting Authority) will be investing in a Cloud Condensation Nucleus counter (CCN counter). A Cloud Condensation Nucleus counter (CCN counter) is an instrument that measures the ability of atmospheric particles to serve as cloud nuclei. In principle, the instrument simulates the conditions that atmospheric particles are exposed to in the atmosphere when clouds are formed. This way, potential particles that may form cloud droplets in the atmosphere, can be identified. Other particles, that are unlikely to form cloud droplets under atmospheric conditions when clouds are formed, are also identified. The information on CCN ability is important to understand the impact of atmospheric particles on climate change.