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UP: Fachverband Umweltphysik

UP 4: Poster Session

UP 4.13: Poster

Tuesday, March 8, 2016, 16:00–17:30, Foyer H41

Ice nucleating properties of feldspar in immersion, deposition and contact freezing modes — •Michael Koch, Nadine Hoffmann, Andreas Peckhaus, Thibault Hiron, Alexei Kiselev, and Thomas Leisner — , Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology (KIT), Karlsruhe

Recently we have conducted an extensive experimental investigation of the ice nucleating efficiency of K-feldspar in three heterogeneous freezing modes: immersion freezing, using the freezing droplet assay, deposition nucleation of ice on the feldspar particles in the humidified flow cell, and the contact freezing by exposing a suspended supercooled water droplet to the flow of feldspar particles. We compare the ice nucleating efficiency of feldspar in these three modes by applying the concept of ice active cites being randomly distributed over the surface of ice nucleating particles. We show that with this approach, the observed quantities (fraction of frozen droplets as a function of time, onset water vapor supersaturation, contact freezing probability) can be consistently described with the limited set of parameters defined within the classical nucleation theory formulation. Finally, we discuss the ageing effect on the ice nucleating efficiency of various feldspar varieties.