(Wine-Searcher) - Sonoma County already has 16 AVAs, but growers in the Petaluma Gap are applying for their own sub-appellation.

The Sonoma Coast is the source of some of America's best wines. It's also one of the California's largest and most meaningless American Viticultural Areas, covering nearly half of Sonoma County and stretching more than 30 miles from the actual coast.

Now some growers in the Petaluma Gap, which makes up a big chunk of the southern part of the Sonoma Coast AVA, are planning to apply for their own sub-appellation. They aren't alone: at least one other group also wants to slice up the giant AVA into smaller bites of cool-climate real estate.

But that doesn't mean it will happen. Fort Ross-Seaview needed eight years to be approved by the U.S. government as a sub-appellation of the Sonoma Coast, while a proposed Freestone-Occidental sub-AVA was rejected last year after four years of consideration.

The argument for what defines Petaluma Gap is unusual. Most AVAs, and most wine regions worldwide, are defined by geographical features like mountains and valleys and, in more precise cases, by types of soil. Petaluma Gap would be defined by wind.

"We get wind of over 40 mph every afternoon," says Ana Keller, owner of Keller Estate and president of the Petaluma Gap Winegrowers Alliance. "It creates an agricultural haven."