[Zurück]

P. Baloh, H. Grothe, K. Whitmore:
"Laboratory Models of Ice Cloud Nucleation";
Poster: 13. Österreichische Chemietage, Wien; 24.08.2009 - 27.08.2009; in: "13. Österreichische Chemietage", (2009), ISBN: 978-3-900554-66-8; Paper-Nr. PO-56, 1 S.

For the Earth´s weather and climate system, clouds are of major importance. On the one
hand they cool by reflecting parts of the solar radiation and on the other hand they heat
by absorbing solar radiation and by trapping the outgoing infrared radiation. However,
the latest report of the international panel of climate change (IPCC) presents clouds and
aerosols as the largest non-anthropogenic uncertainties of earth´s radiation balance [1].
Therefore, a lot of research is directed to this issue [2]. Recent lab studies show that
droplets isolated in an oil-matrix allow studying the homogeneous ice crystallization
[3]. From certain concentrations on, carboxylic acids prevent the ice growth. Inspired
by those results further investigations on this system were done by using different
analytical techniques. For these measurements, the matrices were cooled down to the
temperature of the upper troposphere (i.e. 213K); where cirrus ice clouds regularly
form. Here, citric acid was used as a proxy for the organic fraction of cirrus clouds.
Measurements were done with environmental scanning electron microscopy (ESEM) to
gain morphologic information, with X-ray diffraction (XRD) to gain structural
information and by Raman spectroscopy to gain spectroscopic information. The
collected data can be used to make predictions for cirrus cloud formation and ice
crystallization in general and to start to understand the changes of earth´s radiation
balance in more detail.

http://publik.tuwien.ac.at/files/PubDat_177154.pdf