[_nalply]

An important problem is the fog in the winter months. The nights are longer than in summer and the ground cools off. Moisture condenses and fog develops. The Swiss plateau is special that it is essentially a wide valley about 60 miles wide and 200 miles long. The Rhine and the Rhone rivers leave Switzerland through constrictions. So the cold air tends to stay. During the day the sun warms the clear air above the fog such that a temperature inversion manifests itself. Such a situation can be very stable for weeks. Sometimes it even snows slightly under the fog cover. The Swiss living in the plateau complain about the depressing dark and gray weather and try to flee as often as they can by going up somewhere, sometimes the next hill is enough if the fog cover is not very high. Some cities are more affected than others, for example Zurich, Lucerne and Aarau can have months of fog some years.

Google sea of fog switzerland to get some pictures. These are beautiful.