Years ago I was asking a colleague from California about a Napa Valley wine, inquiring naively if the bottle I had bought was a good year. “Every year is a good year,” he said. It had me wondering. Why is there so much variation in wines from Georgia, or, say, the Burgundy region in France? The center of Burgundy wine production is in Beaune, latitude 47 degrees north. In Germany, the popular Moselle wines grow even farther north. Worldwide, much more wine comes from areas near 35 degrees latitude, where the sunlight is stronger. Georgia would qualify in that regard. But the most consistent wine-producing areas are on the southwestern sides of the Earth’s continents.
Grapes love sunshine. They do less well in highly changeable weather. On a grand scale, the weather patterns on each side of the Pacific and the Atlantic Ocean are controlled by the subtropical highs. Giant areas of air sink down toward the water surface, centered near 30 degrees north of the equator. High pressure means clear sky and an outflow of air away from the center. Air coming out of the highs flows clockwise in the northern hemisphere and counterclockwise south of the equator. In California, this means wind from the northwest, dragging cool ocean water to the shore. The cool water causes more air to subside, suppressing rain and bringing more sunshine. On the other side of the ocean, South Korea is at the same latitude, but the clockwise windflow brings air from the southeast. This means warm, moist, unstable air and frequent rain.
The same is true for the Atlantic Ocean. Sunny, stable conditions favor Portugal’s and Spain’s wine areas. Across the Atlantic, the subtropical high funnels humid air and changeable weather into Georgia.
The southwestern sides of continents have the advantage. In South America, vast vineyards near Casablanca, Chile produce a wealth of wines. In southwestern Australia, dozens of wineries dot the countryside near Perth and beyond. The same is true for the southwestern corner of South Africa, who ranks tenth in world production of chardonnay, sauvignon blanc and chenin blanc.
Due to our changeable weather, Georgia’s wineries can’t achieve the massive volume and worldwide distribution that’s common to the southwestern sides of continents. On the other hand, it leaves opportunity for discovery and treasure hunts that make our smaller wine country unique.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.