This research investigates the transformation of maritime polar air into continental polar air in the Arctic during winter. The evolution of the vertical profiles of temperature and humidity is simulated using a one-dimensional model. The following physical processes are examined 1) surface enthalpy flux; 2) infrared radiative cooling due to emission by CO2, water vapor, water droplets, and ice crystals; 3) gravitational setting of the condensed water, 4) turbulent mixing, and 5) subsidence. The modeled formation of continental polar air is dominated by the radiative cooling due to emission by ice crystals and water droplets. The model reproduces the formation of low-level clouds that are frequently observed in these cold air masses, and also the phenomenon of “cloudless” ice crystal precipitation. The model requires two weeks for the formation of fully-developed continental polar air, although after only four days of cooling the air has acquired most of the air mass properties. The rate of cooli... Abstract This research investigates the transformation of maritime polar air into continental polar air in the Arctic during winter. The evolution of the vertical profiles of temperature and humidity is simulated using a one-dimensional model. The following physical processes are examined 1) surface enthalpy flux; 2) infrared radiative cooling due to emission by CO2, water vapor, water droplets, and ice crystals; 3) gravitational setting of the condensed water, 4) turbulent mixing, and 5) subsidence. The modeled formation of continental polar air is dominated by the radiative cooling due to emission by ice crystals and water droplets. The model reproduces the formation of low-level clouds that are frequently observed in these cold air masses, and also the phenomenon of “cloudless” ice crystal precipitation. The model requires two weeks for the formation of fully-developed continental polar air, although after only four days of cooling the air has acquired most of the air mass properties. The rate of cooli...