EGU2020-2889, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Thermal imaging of a shattering freezing water droplet

Judith Kleinheins1,2, Alexei Kiselev2, Alice Keinert2, and Thomas Leisner2,3
Judith Kleinheins et al.
  • 1Institute of Thermal Process Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany (
  • 2Institute of Meteorology and Climate Research - Atmospheric Aeorsol Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
  • 3Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany

The freezing of a supercooled water drop freely falling through a mixed-phase cloud is an ubiquitous natural process fundamental for the formation of precipitation in clouds. The freezing is known to proceed in two stages: first, a network of ice dendrites spreads across the volume of a supercooled droplet resulting in ultrafast release of latent heat and warming of the droplet up to the melting point of ice; during the second stage a solid ice shell grows from the outside into the droplet, leading to a pressure increase inside the liquid core. Once the pressure gets too high, either the shell cracks open or the droplet explodes. The resulting secondary ice fragments start growing in the water-saturated environment or cause the freezing of neighbouring droplets. This secondary ice production mechanism is important for the rapid glaciation of mixed-phase clouds, however, the details of the underlying mechanisms are poorly understood. To quantify this process of ice multiplication, the evolution of the droplet’s surface temperature during the second freezing stage was investigated with a high-resolution infrared thermography system (INFRATEC). Drops of about 300 µm diameter were levitated in an electrodynamic trap under controlled conditions with respect to temperature, humidity and ventilation. The surface temperature of the droplet was measured with the IR system while the freezing process and shattering of the freezing droplet was recorded by a high-speed video camera. Combining experimental results and comprehensive process modelling, we explore the thermodynamic conditions beneficial for secondary ice production upon freezing of freely falling drizzle droplets.

How to cite: Kleinheins, J., Kiselev, A., Keinert, A., and Leisner, T.: Thermal imaging of a shattering freezing water droplet , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2889,, 2020


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