The 2019 Benjamin Y H Liu Award of the American Association for Aerosol Research, which recognises outstanding contributions to aerosol instrumentation and experimental techniques, has been awarded to CERN’s Jasper Kirkby for his investigations into atmospheric new-particle and cloud formation using the unique CLOUD experiment at CERN, which he originated. The award committee described CLOUD as “arguably the most effective experiment to study atmospheric nucleation and growth ever designed and constructed, really by a country mile”, and said of Kirkby: “His irrepressible will and determination have adapted the culture of ‘big science’ at CERN to a major atmospheric science problem. Along the way, Jasper has also become a world-class aerosol scientist.”