Minimal cooling rate dependence of ice nuclei activity in the immersion mode

We present new measurements of the time dependence of the ice‐nucleating ability of a wide range of materials including the minerals montmorillonite and kaolinite, the biological proxy ice nuclei Icemax, and flame soot generated from the incomplete combustion of ethylene gas. We also present time dependence for ambient ice nuclei collected from rainwater samples. Our data show that the time dependence for all materials studied here is weak, suggesting that the modified singular approximation is valid over the range of times and temperatures encountered for mixed phase clouds. Key Points Cooling rate dependent measurements of ice nuclei present in rainwaterCooling rate dependence for heterogeneous ice nucleation is minimalFifty hours exposure changes median freezing temperatures by less than 3K