# Ice nucleation in the wake of warm hydrometeors

## TL;DR

This study reveals that evaporative supersaturation in the wake of warm hydrometeors can significantly increase ice nucleation, explaining the high ice particle concentrations observed in mixed phase clouds.

## Contribution

It demonstrates laboratory evidence that warm water drops can induce high ice nucleation rates through evaporative supersaturation, extending understanding of cloud ice formation mechanisms.

## Key findings

- Evaporative mixing in the wake causes high supersaturation.
- Enhanced ice nucleation in the wake explains observed ice concentrations.
- Results applicable to real atmospheric mixed phase cloud conditions.

## Abstract

The formation of ice in mixed phase clouds greatly impacts Earths hydrologic cycle. The intensity, distribution and frequency of precipitation as well as radiative properties of clouds in the mid latitudes are strongly influenced by the number concentration of ice particles. A long standing riddle in mixed phase clouds is the frequent observation of measured ice particle concentrations several orders of magnitude higher than measured ice nucleating particle concentrations. Here, we report laboratory observations of copious cloud droplets and ice crystals formed in the wake of a warm, falling water drop. Aerosols were activated in the transient regions of very high supersaturation due to evaporative mixing in the wake. We extend these results to typical mixed phase atmospheric conditions, and our calculations show that the induced evaporative supersaturation may significantly enhance the activated ice nuclei concentration in the particles wake.