Clouds have a profound effect on the climate, but we know surprisingly little about how they form. Erika Sundn, researcher at the University of Gothenburg, Sweden, has studied how extremely small cloud particles can dispose of excess energy. This knowledge is necessary to understand processes in the atmosphere that affect global climate change.
The models that have been built to describe climate change contain a major source of uncertainty, namely the effects of clouds. The UN Intergovernmental Panel on Climate Change points out in its climate report for 2007 that new knowledge is needed in this field. It is namely the case that clouds can act in two ways: they may be a mirror that reflects radiation from the sun back into space, and they may be a blanket that seals in the heat emitted by the Earth. Mapping the formation and dispersion of clouds may, therefore, be a key step in climate research.
"One important stage is understanding the fundamental properties of the particles involved", says Erika Sundn, doctoral student at the Department of Physics, University of Gothenburg.
Ammonia may play an important role
Erika has studied small particles known as "clusters", which contain between 3 and 300 molecules. One line of research has investigated how water clusters dissipate excess energy, and this will help to understand how water droplets grow and how they evaporate. These are the processes by which ice and liquid water are transformed into water vapour (gas).
Another line has investigated how the clusters are influenced by ammonia, which is an important component of the atmosphere.
"I investigated water clusters that contained a small fraction of ammonia, and compared these with pure water clusters. I was able to show that the ammonia contributed to the stability of the clusters, and prevented them evaporating so rapidly. It may be that ammonia plays an important role in the early stages of cloud formatio
|Contact: Erika Sundn|
University of Gothenburg