-------- Forwarded Message -------- Subject: [EXT] Seminar mathematics and atmospheric physics on May 21 Date: Mon, 19 May 2025 09:17:06 +0200 From: Peter Spichtinger spichtin@uni-mainz.de

Dear all,

this is a kind reminder for the next talk in our monthly seminar on mathematics and atmospheric physics.

On Wednesday, May 21, Axel Seifert (German Weather Service) will talk about

Ice microphysics in higher dimensions: super-particles and the geometry of snowflakes

Abstract: Understanding snowflake formation requires modeling the interplay between complex microphysical processes and environmental conditions. In this talk, I will present ice microphysics in a higher-dimensional phase space using a stochastic super-particle approach, where each numerical particle represents an ensemble of real ice crystals. Building on the McSnow modeling framework—which includes detailed habit prediction for ice particles—we extend the representation of snowflake geometry to more realistically capture particle growth and aggregation. In the first part of the talk, I introduce an ML-based coarse-graining method that enables the derivation of a multi-moment, P3-like bulk microphysics scheme directly from super-particle simulations—providing a systematic link between Lagrangian and Eulerian modeling frameworks. In the second part, the focus shifts to the variability in the geometry of aggregate snowflakes. We show that the maximum dimension of aggregates — given fixed mass and monomer count — follows a lognormal distribution, revealing the stochastic nature of the aggregation process. This rigorous treatment offers new insights into the morphological diversity of snowflakes and contributes to improved representations of ice particles in weather and climate models. And even if it doesn’t make the forecasts any better—or solve the problem of climate change—we gain a deeper understanding of clouds, and have some fun doing applied math along the way.

The seminar will start at 16:00 local time (i.e. 14 UTC). The zoom link is provided below (starting already at 15:45 local time).

The next dates for the seminar are as follows June 4 Jana de Wiljes, TU Ilmenau

Please also check the homepage of the seminar: https://www.staff.uni-mainz.de/spichtin/seminar.html

Best, Peter

PS: Please feel free to distribute the announcement to others

Reminder: The registration and abstract submission for the SCALES conference https://model.uni-mainz.de/scales-conference-2025/ are still open ...

----------------------- Peter Spichtinger is inviting you to a scheduled Zoom meeting.

Topic: Seminar Mathematics and Atmospheric Physics Time: May 21, 2025 03:45 PM Amsterdam, Berlin, Rome, Stockholm, Vienna Join Zoom Meeting https://uni-mainz-de.zoom.us/j/68522641413?pwd=SX2azpaqe4yBP0Cy907rvhVk27Kym...

Meeting ID: 685 2264 1413 Passcode: 293629

---

One tap mobile +496950500952,,68522641413#,,,,*293629# Germany

-- ---------------------------------------------------------------- Prof. Dr. Peter Spichtinger Theoretical cloud physics Institute for Atmospheric Physics (IPA) Johannes Gutenberg University Mainz J.-J.-Becherweg 21, 55128 Mainz, Germany

Office: 05-163 Phone: +49 (0) 6131 39 - 23157 Fax: +49 (0) 6131 39 - 23532 email:spichtin@uni-mainz.de

https://www.staff.uni-mainz.de/spichtin/ https://theoryofclouds.ipa.uni-mainz.de/ https://binary.uni-mainz.de/ https://model.uni-mainz.de/ ----------------------------------------------------------------