Acidity is vital for vino.

When acidity is too low, wine is dull and flat. When acidity is too high, wine is tart and sour.

When acidity is just right, wine is a palate-cleansing food friend, a delicious delight.

Wine acidity sweet spot is between 3 and 4 pH. Most wines land between 3.3 and 3.8. Whites tend to be more acidic than reds. For comparison, milk is around 6.6 and lemonade 2.5

Once upon a time, wine wonks imagined they could spin any grape into gold, but that hubristic notion proved wrong. To make good wine, you must start with a good grape farmer.

A good grape farmer starts with good soil and an obliging climate.

Warm climates produce wonderfully fruity, sweet grapes. But warm throttles acidity.

Cool climates produce wonderfully acidic wines. But cool throttles sweet fruitiness.

There are places where climate embraces wine’s vines—warm days, cool nights—and, guess what, that’s where world’s great wines are made. Something to remember next time you buy a bottle.

Chardonnay is classic example of role played by land and climate (“terroir”). French chablis is chardonnay produced in cool climate; winemakers know how to make a flinty, food-friendly wine. Chablis is so acidic, it typically requires malolactic fermentation—a process that turns malic acid into softer, buttery flavors. Chaptalization—adding sugar—is permitted. Adding acetic acid is not.

California chardonnays fight for acidity in warm, fruit-friendly climate. Californians cannot add sugar  to increase sugar levels; no problem, they don’t have to. Adding acid—allowed.

Both places produce charming, different chardonnays. Such is wine’s refulgent wonder.

Tasting notes:

• Dark Horse Chardonnay 2013: Pear, peach, apple, butterscotch, caramel, on-lees aging adds nutty flavor; oak not over-the-top; good acidity; easy drinking value with fillip of flair; sip cool by pool. $10

• Mirassou Pinot Grigio 2013: Crisp acidity; citrus, orange zest, pear, peach; soft mouth; delicious, sweet ripe-fruit freshness. $12

• Frei Brothers Russian River Valley Reserve Chardonnay 2013: Polished exemplar of Russian River chard; green apple, honeysuckle, melon, pineapple; cool climate vineyard delivers superb acidity to crisply complement food; graceful easy drinker. $20

Last round: Wine is greatest human invention. Yes, wheel is impressive, but it does not go nearly as well with pizza.

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