Ice nucleus

An ice nucleus is a particle which acts as the nucleus for the formation of an ice crystal in the atmosphere. An ice nucleus is a particle which acts as the nucleus for the formation of an ice crystal in the atmosphere. There are a number of mechanisms of ice nucleation in the atmosphere through which ice nuclei can catalyse the formation of ice particles. In the upper troposphere, water vapor can deposit directly onto solid particle. In clouds warmer than about −37 °C where liquid water can persist in a supercooled state, ice nuclei can trigger droplets to freeze.