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CU professor explains the science behind Coors Field homers

All Star Game Denver
Posted at 2:10 PM, Jul 12, 2021
and last updated 2021-07-12 19:19:48-04

DENVER — The baseballs will be flying high tonight as the game's biggest sluggers square off for the Home Run Derby.

Coor's Field is notoriously a hitter's ballpark, where baseballs reportedly go 5 to 10 percent farther on average than at sea level, but why?

We got Dr. Peter Hamlington, an associate professor at the University of Colorado, who is an expert in fluid dynamics, to explain the science behind the long balls:

What does fluid dynamics have to do with home runs at Coors Field?

"So fluid dynamics is the study of primarily air and liquid or water flow on earth, and the reason it's so relevant to so many sports is that many sports involve some type of object flying through the air and occasionally going through water. Baseball is certainly no exception, and fluid dynamics concepts have a lot of bearing on the flight of a baseball."

Are you a baseball fan?

"I am a baseball fan. Grew up supporting the Chicago Cubs. And more recently have been trying to follow the Colorado Rockies. I'm also a golfer, and it's a big deal with golf. It explains why golf balls are dimpled and why golf balls actually travel further and humid air than dry air, which is something that people don't really expect."

There is talk right now that we just might see the longest home run on record for this Home Run Derby at Coors Field. What is the science behind that?

"I think that's certainly a possibility for tonight, and there's a few primary factors that affect the length of home runs at Coors stadium. The first and most obvious one is our high altitude and the lower air density that comes with that. Air density in Colorado at Mile High conditions is about 20% less than at sea level, and so this results in less air resistance and baseballs that travel a bit further. There's some other competing effects. So for example, when a baseball is hit it's often spinning and a well-hit home run ball will have backspin. That actually creates lift on a baseball, and via the Magnus effect. It turns out that at altitude, that lift effect is actually somewhat less. So that would suggest that hit balls may go less far. But in the end, this effect due to the lower air resistance baseballs are documented to travel five to 10% further at Coors field."

Do you think we're going to see that over 500-foot hit that they're talking about right now?

"I'll say yes, and the other part of this is that baseballs at Coors Field have been kept in humidors for the past almost 20 years since 2002. And the reason for that is that a dry baseball is not only lighter, but it's also a bit more bouncy, and so comes off the bat with higher velocity. That's actually really resulted in an increased home run leading up to 2002. When they instituted the humidors, which is where they store the baseballs in a humid environment, the home run rate at Coors Field went down about 25%. And so for the Home Run Derby, they are actually going to remove the use of the humidor. So not only are we at altitude, but the baseballs will be finely tuned and ready to fly out of the park."