The Piedmont region is located in the foothills of the Alps forming its border with France and Switzerland. To the northwest is the Valle d'Aosta; to the east is the province of Lombardy with the Liguria region forming its southern border along the Apennines. In addition to the vast mountainous terrain, the Po Valley consumes a large area of available land-leaving only 30% of the region suitable for vineyard plantings. The valley and the mountains do contribute to the areas noted fog cover which aides in the ripening of the Nebbiolo grape (which gets it name from the Piedmontese word nebbia meaning "fog"). Although the winemaking regions of the Piedmont and Bordeaux are very close in latitude, only the summertime temperatures are similar: the Piedmont wine region has a colder, continental winter climate, and significantly lower rainfall due to the rain shadow effect of the Alps. Vineyards are typically planted on hillsides altitudes between 490–1150 ft (150-400 metre). The warmer south facing slopes are mainly used for Nebbiolo or Barbera while the cooler sites are planted with Dolcetto or Moscato.