From Wall Street Journal:
Twins Hitters, Meet the Elements
Baseball is a game of inches, but the impact of the Minnesota cold on fly balls at brand new Target Field is better measured in feet.
Cold air is more dense and thus more resistant than hot air. The same fly ball travels about four feet less for every 10-degree drop in temperature, says Robert Adair, Yale physicist and "The Physics of Baseball" author. This could play a critical role as the Twins adapt to outdoor baseball: The average low temperature in Minneapolis during the baseball season ranges from 36 to 63 degrees, according to the Weather Channel. The Twins former digs, the indoor Metrodome, was maintained at a constant 70 degrees.
To put the effect of cold weather to a test, baseball sabermetrician Sean Kelly measured hundreds of thousands of batted-ball trajectories under various temperatures as part of a study on how Target Field will influence run scoring. He simulated that at the Metrodome, a ball hit at a 90-to-108 mph initial velocity and an angle above the horizontal of 22 to 38 degrees would clear the fence 51.3% of the time. But at Target Field, these fly balls cleared the fence at a 37%-to-51% rate?depending solely on the thermometer. Less distance on fly balls also means fewer doubles and triples that barely elude a defender's outstretched glove.
Mr. Kelly also examined a tougher park architecture for homers in left and right center and ballpark orientation relative to prevailing local winds. The results? "Target Field could very well be the AL version of Petco," writes Mr. Kelly, referring to the Padres' home that has depressed run scoring 24% since 2007.
Cold-Air Baseball
A computer simulation shows how Minnesota temperature dictates how many "borderline home runs" would clear the fences.*
Temp.
Outside METRODOME
HR RATE TARGET FIELD
HR RATE
80 51.3% 50.9%
70 51.3% 48.3%
60 51.3% 45.6%
50 51.3% 42.7%
40 51.3% 39.8%
30 51.3% 36.8%
*Borderline HRs are balls hit 90 to 108 mph at an angle of 22 to 38 degrees
Source: Sean Kelly, Katron.org