Sonoma’s strength as mentioned earlier lays in her sub regions (known as AVAs for the sake of this essay) that display an alarming array of microclimates.  The existence of these microclimates allows producers to successfully grow and make quality Pinot Noir and Chardonnay, in addition to Cabernet Sauvignon, Merlot, and Zinfandel.  There exist warm and dry sub regions such as the Dry Creek Valley, Knights Valley (in reality simply a climatic and geographic extension of Napa Valley), in addition to cool and damp climates such as the Russian River Valley and its sub region, Chalk Hill.  Ocean breeze and fog help cool the latter two regions enabling Sonoma winemakers to produce great examples of the finicky Pinot Noir.  Knights Valley because of its soil, which is both rocky and gravelly, and warm climate, is perfect for raising quality Cabernet.  Sonoma County Green Valley and Los Carneros (a sub region shared with its rival, Napa) are ideal for producing quality fruit for sparkling wines.  Sonoma Valley, while ideal for Cabernet, is also well-suited to Zinfandel because of her dry and warm conditions and her ability to ward off fog that would create a mould and rot problem for Zinfandel.