Weather and Baseball

This chapter relies exclusively on the work of Dr. Robert K. Adair who from 1987 to 1989 held an appointment as “Physicist to the National League”. His engaging 1990 paperback entitled: The physics of baseball offers a fascinating array of findings dealing with everything from the dynamics of a ball in flight, to the physics of pitching and batting, to the properties of various types of bats. Most of the technical stuff, formulae, calculations, etc. is conveniently tucked away at the end of each chapter leaving those of us with only a smattering of physics free to read merrily on oblivious to the underlying calculations.

Few people would be surprised to learn that the performance of baseball players and other athletes can be affected by the weather. Gusty winds make it especially difficult for outfielders to catch the high fly ball. At the same time, pitchers may lose some of their control when the temperature hovers around 95 degrees Fahrenheit. As for the performance of batters, fairly precise estimates have been made of the influence of weather factors on the flight of a well-hit pitch.

To begin with, consider the influence of the wind on the distance a ball travels when it is hit into a 10 mph headwind or alternately, a 10 mph wind blowing from the plate toward center field. Thus for example, a ball that leaves the bat at the optimum angle of 35 degrees above the horizontal at 90 mph would travel about 315 feet while one hit with a velocity of 120 mph would land about 455 feet from home plate. Now note the influence of a 10 mph wind. A 400 foot drive with a following wind will land 430 feet from home base while the same 400 foot drive hit into a 10 mph headwind will drop 370 feet from home plate. What would have been a home run on a calm day is at best, a double with a breeze blowing in from center field.

Altitude is a further factor affecting the performance of batters. Home run hitters toying with the center field fence at sea level will find the same hit clears the fence with ease in cities that are well above sea level. For example, the 400-ft. drive hit in Yankee Stadium (close to sea level) will fly an additional 5 feet in Milwaukee and 6 feet in Kansas City. But these advantages to hitters pale by comparison with that provided members of Colorado’s National League franchise, the Colorado Rockies. The 400-ft drive in Yankee Stadium now carries a further 40 feet! The rarefied atmosphere in the mile high city of Denver makes it a batter’s paradise. In the case of long-ball hitters, being traded to the Rockies may be a blessing in disguise. Finally, Denver pitchers with a good fastball will find it a little faster. However, their curveball will not curve quite as much as it would at sea level.

Other factors can similarly affect the trajectory of the 400-ft home run. A difference of 20 feet can be expected between the distance the ball will fly on a cold day in Milwaukee (45 degrees F) and a hot afternoon in Atlanta (95 degrees F). In addition to temperature, barometric pressure similarly affects the distance a ball will travel. For each one-inch reduction in air pressure, the ball can be expected to sail a further 6 feet. Even the humidity can add extra distance. Water vapor being slightly lighter than air, very humid conditions can also add a little something extra to the long ball hit to center field. To summarize, a hot, humid day in Denver with a breeze blowing out to center field comes close to a slugger’s idea of heaven.

About Sport Science Secrets | Table of Contents | Sample Chapters

Page last modified October 17, 2007