 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 area's noted fog cover which aides in the ripening of the Nebbiolo grape (which gets its 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