Baseball in Thin Air

Denver's mile of altitude does something to a baseball that no other major league city has to reckon with. At roughly five thousand two hundred and eighty feet, the air is thinner, which means less drag on a struck ball. A batted ball at Coors Field tends to carry several percent farther than it would at sea level, and in the nineteen nineties that produced video game scores and a reputation as a hitter's paradise.

The Colorado Rockies answered with chemistry rather than fences. Beginning in two thousand and two, the club began storing its baseballs in a humidor, a climate-controlled chamber held at a steady temperature and humidity. In Denver's naturally dry air, untreated baseballs shrink and harden, flying farther and gripping less.

The humidor restores moisture, making each ball slightly heavier and less lively. After the team adopted the practice, home runs at Coors Field fell noticeably. It is a rare case of a sports venue editing the laws of physics with a walk-in closet, and the rest of the league eventually took notice.

Other clubs eventually adopted humidors too, an idea that started in the thin air of the Front Range.