Noctilucent clouds (NLC) at the polar summer mesosphere are highly sensitive to atmospheric conditions, therefore they are an important climate indicator. In this thesis, an ice particle model is combined with circulation models to simulate the formation of NLC throughout the particle life cycle: Only 1% of ice particles grow to visible size (50 nm). The main part of particle growth takes place at 83 km altitude, within 6 hours prior to observation and is accompanied by upwelling. By using cylindrical particle shape, the simulated optical signal is made consistent with measurements.