A new theory of heterogeneous ice nucleation for application in cloud and climate models

A new formulation is presented of the thermodynamical theory of heterogeneo us ice crystal nucleation in clouds by freezing. This theory unifies and ex plains the empirical ice nuclei dependence on temperature and supersaturati on, predicts crystal formation via condensation-freezing at a subsaturation over water. The theory also explains observations of high nucleation rates and crystal concentrations at warm (-5 > -12 degreesC) temperatures when t he splintering mechanism may be not effective. This theory can be applied t o parameterizations for use in cloud and climate models.