While caddying this summer, I keep hearing players say the golf ball wasn’t flying far that day because “the air is heavy.”
Somewhere in the back of my mind—way, way back, behind the Joe Perry Project albums and the empty cans of Red, White and Blue Beer—I thought I remembered that heavy air helps the flight of the golf ball.
With insatiable curiosity, I stepped into the TaylorMade product trailer when the Travelers Championship pulled into Cromwell, Conn. and TPC River Highlands to find out the answer. (I chose TaylorMade because I love their golf ball.) The kind gentleman inside put me in touch with Eric Loper who has the title of Product Development Manager – R&D Golf Balls.
I emailed him and his answer, long and full of detail as you would expect from a Product Development manager, confirmed (sort of) my recollection. In fact, humidity has very little effect on the flight of a golf ball. I’ll let Eric explain why.
Changes in air humidity do influence golf ball performance, but the change is quite small and counter-intuitive. The counter-intuitive part is that increasing humidity makes the golf ball fly slightly lower and longer. (I was right.) The extra carry distance gained on a very humid day is small though. For example, changing the humidity from 10% to 100% will only lower the ball peak height less than a foot and add about 1 yard of extra carry distance, and that’s at tour professional ball speeds (ball launch speed of 175 mph).
If you’re curious (I am!) why increasing humidity increases carry distance, here’s an explanation. (The moment of truth.) The addition of water vapor to air actually reduces the density of the air, and it’s this reduced density that lowers both lift and drag forces on the ball: lower lift reduces the peak height and lower drag increases carry distance. People often think that higher humidity equates to air that’s heavy or more dense due to the increase in water content (Yes they do). This can cause some confusion since we’re used to thinking of water as being heavy, and it is in liquid form. But when water is added to the air it is in vapor form and the molecular mass of water vapor is 18 g/mol, where the molecular mass of dry air is about 29 g/mol. (I have not idea what g/mol means.) So on humid days lighter water molecules displace some of the heavy air molecules and the net effect is less dense air.
What this boils down to, sorry to say, is that all the those players who thought the air was knocking down their shots were making poor contact.
(I received no compensation from TaylorMade for touting their golf balls but if they would like to extend a modicum of appreciation to me for doing so, my contact information can be found in the About section of this website.)
“No bribe too small.”
~Randy Smith
