A numerical study of the contrail-to-cirrus transition

Abstract

A numerical 2D-simulation of the transformation of a contrail in its vortex phase to a cirrus-like cloud during the dispersion phase has been performed using a model that handles both wake dynamics and ice micro-physics. The contrail is located in an environment characterized by measured profiles of wind and temperature. The ambient humidity at cruise level slightly exceeds ice-saturation. The thermal structure of the atmosphere causes a strong vertical growth of the contrail cloud, even into a dry layer, until a stably stratified layer is reached. Thereafter the cloud expands mainly horizontally and after 30 min it eventually disappears because of entrainment of dry ambient air.