Ultraclean chamber produces new results on cloud droplets

Researchers at the University of Helsinki have developed a device which has for the first time enabled measurement of extremely small, just formed atmospheric particles in closely controlled circumstances.

Researchers at the University of Helsinki have developed a device which has for the first time enabled measurement of extremely small, just formed atmospheric particles in closely controlled circumstances.

Formation of atmospheric small particles can be studied without the effect of impurities in the ultraclean CLOUD chamber that was built in CERN, the European Organization for Nuclear Research.

– This is a big step for atmospheric research, says Academy Professor Markku Kulmala from the Department of Physics. Kulmala has led a group of 14 researchers at the University of Helsinki, which took part in a study published in the Nature journal.

The University of Helsinki was responsible for the equipment that measures the smallest, just formed particles and ions. The equipment made it possible to follow the particle formation process from the molecular level and to recognise vapours linked to it.

– For the first time, we can observe the formation speed of particles in the scale in which they are born, says Katrianne Lehtipalo, a post-doctoral researcher at the Department of Physics.

Aerosol particles cool the climate by reflecting sunlight and forming cloud droplets. However, the birth mechanisms of the particles are not yet known in detail and the effect of cosmic rays in the climate through clouds has also remained a contentious issue.

According to researchers, accurate laboratory experiments like the ones that have now been performed serve to decrease uncertainties related to climate models.

The article published in Nature on 25 August is the first result of the CLOUD (Cosmics Leaving OUtdoor Droplets) project. The aim of the project is to find out how new small particles are created in the atmosphere. CLOUD is the first cooperation project between physicists and atmosphere researchers at CERN. In all, 17 institutes from nine countries participated in the project.

The CLOUD project was launched at the initiative of Finnish physicists Markku Kulmala and Ari Laaksonen et al. and physicists such as Jasper Kirkby at CERN. The Finnish CLOUD project is a project of the Helsinki Institute of Physics, and the institute was involved in the initiative leading to the creation of the project.

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Text: Minna Meriläinen-Tenhu
Photo: Katrianne Lehtipalo
5.9.2011
Translation: AAC Global
University of Helsinki, digital communications


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