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H. Grothe:
"Laboratory simulations (1)";
Vortrag: SPECAT 09 Summer School, Jaca, Spain (eingeladen); 29.06.2009 - 10.07.2009; in: "Spectroscopy of the Atmospheres", R. Escribano (Hrg.); (2009), S. 144 - 156.

The atmosphere exhibits strong fluctuations in temperature and chemical composition. Therefore, many aerosol particles are not in thermodynamic equilibrium with their environment. These non-equilibrium conditions influence the particle´s chemical composition and phase as well as the morphology, the surface structure and finally the surface chemistry. These physicochemical properties cannot be determined in field measurements but are accessible by laboratory model experiments. In the framework of this lecture different models for aerosol investigations are presented and their assets and drawbacks are discussed.
In the past, aerosol constituents of different origin have been investigated. However, this lecture focuses particularly on the cryo-particles of the upper troposphere and the lower stratosphere. Thus, the main constituents are water ice and nitric acid hydrates besides traces of sulfuric acid and organic acids. Only recently Murray (2008) has shown that cubic ice (i.e. the metastable modification of water ice at ambient pressure) has a good chance to exist in Cirrus Clouds. The same is also true for the Polar Stratospheric Clouds where metastable nitric acid hydrates have been postulated. Hence, we are looking for laboratory models suitable for metastable icicles.