Seminar

Abstract

It is important to know the phase and physical properties of aerosol and cloud particles at the top of mid-level and high tropospheric clouds - anvils and the stratiform cirrus that originate from them - in order to better estimate their effects on the energy balance, the atmospheric moisture budget and regional circulation patterns. This talk revisits the formation of pristine ice crystals from homogeneous freezing of a population of cloud droplets - arguably the most basic water-to-ice phase transition path in liquid tropospheric clouds - by means of a theoretical analysis of the involved processes. Characteristic differences of the phase transition in different freezing-growth regimes will be illustrated by means of parcel simulations. Ramifications of these findings for the dynamical control of ice nucleation in cold cloud outflow regions are outlined..

---

Bernd Kärcher is a CIRES Visiting Fellow at CSD, from the Institute of Atmospheric Physics, German Aerospace Center.