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Published online 7 December 2007 | Nature | doi:10.1038/news.2007.362
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Humid baseball theory a bit wet
Physicists show humidors fail to alter ball aerodynamics.
Do dry baseballs go further than wet ones? Not according to new research. The study pours cold water on the practice of using humidified balls, which is done in some parks in an attempt to level the playing-field.
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In an analogy to the cricket world it is widely believed for the wrong reasons that a spinning ball will swing more in humid weather because the ball grips the 'heavier' air. In fact humid air is less dense than dry air.In my computer simulations the effect can be produced if it is taken into account that a spinning ball will take longer to spin down in less dense humid air and so maintain revs and the forces that make the ball curve (Bernouilli and Magnus) for longer and so curve more.
Regarding the section stating, "Surprisingly, they found that drag actually dropped as balls became more humid. The reason, according to Meyer, is that the increased mass allows the ball to cut through the air more easily. This more than offsets the increased air drag from the tiny increase in surface area." It seems that the first sentence should read, "acceleration due to drag," instead of simply "drag." The actual drag force actually increases as the diamter increases.
I doubt that a pitcher would ever object to his ERA being dragged down.