The Climate of, and Weather in, the Languedoc:    Mountains and Mountain areas

Air temperatures generally decrease with altitude, by about 1°C per 150m This is due not only to low air pressures but also relatively cleaner air (free of dust particles and pollution).  This reduces the amount of diffuse radiation and the heat retaining properties of the air.

Ridges and peaks can create a deep shading effect over adjacent areas.  Temperature differentials in highland areas are therefore often much higher than in flat areas.

Higher wind speeds in mountains result from accelerated airflow up and over the mountain range.  Winds are generally gusty because of the varied relief.  Wind funnelling also occurs in mountain terrain, producing great variation in wind speed. Valley winds tend to occur under clear and settled conditions and are the result of the differential heating found in areas of rugged relief.

Average levels of precipitation also increase with altitude.  When air streams flow over mountain areas they are forced to rise in altitude.  Moist air is cooled, condensation occurs and clouds form.  Turbulent air currents contribute to encouraging rainfall.