1911 Encyclopædia Britannica/Mistral
MISTRAL, a local wind similar to the bora (q.v.), met with on the French Mediterranean coast. The warm Gulf of the Lion (Golfe du Lion) has to the north the cold central plateau of France, which during winter is commonly a centre of high barometric pressure, and the resulting pressure gradient causes persistent currents of cold dry air from the north-west in the intermediate zone. The mistral occurs along the coast from the mouth of the Ebro to the Gulf of Genoa, but attains greatest strength and frequency in Provence and Languedoc, i.e. the district of the Rhone delta, where it blows on an average one day out of two; the record at Marseilles is 175 days in the year. It is usually associated with cloudless skies and brilliant sunshine, intense dryness and piercing cold. With the passage of a cyclone over the gulf, or a rapid rise of pressure following a fall of snow on the central plateau, the mistral develops into a stormy wind of great violence.