Biogenic ice nucleus
From AMS Glossary
biogenic ice nucleus
An ice nucleus of biological origin, particularly bacteria (e.g., pseudomonas syringae) from plant surfaces.
These organisms have threshold temperatures as high as -2°C, being active at the highest temperature known for natural nuclei. They were first identified in leaf litter, collected worldwide. Commercial application lies in nucleation of water spray drops for artificial snow on ski slopes.